Medical Genetics – Clinical practise
MUDr. Jana Šoukalová
Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University
and University Hospital Brno
Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brnol 1
Presentation Contents
̶ Medical genetics - genetic counselling, ethical and legal aspects
̶ Primary and secondary genetic prevention
̶ Prenatal diagnosis
̶ Reproductive genetics – genetic testing of couples with
reproductive disorders
̶ Newborn screening and early postnatal diagnosis
Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno 22
History
Gregor Mendel first publicly
presented results of his research
on plant crossbreeding in 1865.
Audience did not understand his
lecture at the time. Most of the
listeners had no idea what he
was talking about.
1965 Janáček Theatre Brno Conference
to celebrate the
100th anniversary of the
publication of Mendel's
discoveries
1967 – the field of Medical
Genetics was established
Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno3
Medical Genetics 1967…
Healthy Suffer from
disease
Healthy
carriers
• Medical history
• Genealogy
• Karyotype
• Genetic prognosis
Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno4
Medical Genetics 2020….
• Medical history
• Genealogy
• Karyotype
• Molecular cytogenetics – FISH, MLPA, array-CGH
• DNA analysis- scoring of the most frequent mutations,
analysis of hot spot areas, indirect DNA analysis…
Sanger sequencing, MLPA,
NGS – MPS, WES,
Whole-genome sequencing….
• Genetic prognosis
5 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
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Medical Genetics
̶ Medical genetics deals with the diagnosis of hereditary diseases, their therapy and
preventive care
̶ Medical genetics deals not only with medical, but also with social and psychological
aspects of hereditary diseases.
̶ As in all other areas of medicine, it is crucial to make a proper diagnosis and
provide appropriate care.
̶ The care must include not only the affected individual, but also his/her family
members who should also understand the nature and consequences of the disease.
6 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
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Genetic counseling
̶ Combines patients risk assessment with psychological care and educational
activities.
̶ It has evolved into a new healthcare profession.
̶ clinical geneticists are dedicated to the care of patients with genetic
disorders and their families.
̶ In addition to direct, human to human, contact with patients, clinical
geneticists provide necessary laboratory diagnostics and identify
patients/relatives at risk of genetic disorders
7 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
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Genetic disorders
̶ Congenital chromosomal aberrations
̶ Monogenic diseases
̶ Mitochondrial diseases
̶ Diseases with complex inheritance, congenital defects, multifactorial or
polygenic disorders
8 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
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Orphan or rare disesases
̶ A rare disease is defined by a population frequency of less than 5 patients per 10,000 healthy patients.
Patients with rare disease and their families often find themselves in a very difficult life situation
̶ Diagnosis of these diseases requires specialized procedures, and due to the rare occurrence of these
diseases, a correct diagnosis can take several months or even years.
̶ Another serious problem with rare diseases is that there is basicaly no effective cure and if there is an
effective cure, it is usually extremely expensive.
̶ Care for patients with orphan diseases is centralised into specialised centers - European Reference
Networks(ERN)
̶ In the Czech Republic - Czech Association for Rare Diseases (ČAVO) since r.2012
Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno 99
Institute of Medical Genetics and Genomics, University Hospital Brno and Faculty of Medicine, Masaryk University10
What are the major issues affecting people with rare diseses?
̶ Late or incorrect diagnosis
̶ Inaccessible expert health care
̶ Inaccessibility of so-called orphan drugs (i.e. drugs for rare diseases)
̶ Failures in the social support and benefits network due to lack of knowledge on the
part of assessing doctors, social workers, etc.
̶ People with similar diseases who lack patient organizations have limited possibilities
to share experiences
̶ 1 patient per 2000 births
̶ There is cca 6000 – 8000 different diseases,
̶ about 30,000,000 patients with rare diseases,
̶ hundreds of new diagnoses per year,
̶ about 80% of rare diseases have a genetic origin.
̶ In thousands of sick children and adults, not only in the Czech
Republic, doctors do not yet know what disease they suffer from,
which brings considerable complications, it is not clear how to
treat them, include or not include them in the social care system...
Orphan or rare disesases
Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno 1111
European Reference Networks
̶ The ERNs are virtual networks that bring together healthcare providers across
Europe to address complex or rare diseases that require highly specialised
treatment
̶ The networks are established on the basis of Article 12 of EU directive 2011/24
on the application of patients' rights in international healthcare, which obliges
EU Member States to support the European Reference Network, especially in
the field of rare diseases.
̶ In March 2017, 24 ERNs were approved, involving over 900 highly specialised
healthcare facilities from more than 300 hospitals and 26 Member States.
̶ Health care providers in the Czech Republic have been very actively involved in
this networks, with 8 providers participating in 17 networks.
12Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno12
The Czech Association for Rare Diseases (ČAVO) was
established in 2012. The mission of ČAVO is to bring
together organizations for patients with rare diseases and
individual patients, represent their interests and raise
awareness of the specific issue of rare diseases among
healthcare professionals, representatives of state,
international institutions and the public.
http://vzacna-onemocneni.cz/
Czech Association for Rare Diseases
13Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno13
Medical genetic workplaces
̶ Outpatient clinic -> Genetic counselling
̶ Cytogenetic laboratories (prenatal, postnatal, molecular-cytogenetic,
oncocytogenetic)
̶ Laboratories of DNA/RNA diagnostics (monogenic diseases, oncogenetics,
identification of individuals..)
14Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno14
Indications for genetic testing
̶ Families with a history of hereditary disease, chromosomal aberrations, or
developmental defects.
̶ Couples treated for reproductive disorders.
̶ Pregnant women with an increased risk of fetal abnormalities
̶ Consanguineous couples
̶ Persons with an increased risk of induced mutations (environmental
influence)
̶ Gamete donore
̶ Cancer patients
15Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno15
The course of a genetic consultation →
Information gathering
̶ Personal medical history
̶ Family medical history
̶ Genealogical analysis- compilation of at least three-generation family tree
with information about health issues of individual family members
̶ Information about Ethnicity • Consanguinity • (Non)paternity
̶ Informed consent
16Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno16
marriage
divorce
consanguinity
monozygotic twins
cizygotic twins
no offspring
abortion
stillbirth
a man
a woman
suffer from disease
unknown gender
non-penetrating
carrier of disease
disease carrier
proband
deceased individual
Symbols to draw a family tree
Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno17
Family tree
Death of a
newborn
Syndaktilie
Epilepsy
Congenital heart defect
Cleft lip and
palate
Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno18
The course of a genetic consultation →
Clinical genetic examination
̶ Somatic abnormalities – stigmatization – atypical appearance
̶ Atypical behavior, failure to thrive…
̶ Congenital developmental disorders
̶ Psychomotor development
̶ Intellectual disability
̶ Dermatoglyphics
19Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno19
The course of a genetic consultation →
Indication of laboratory and other
specialized examinations
̶ Cytogenetics
̶ Molecular cytogenetics
̶ DNA/RNA analysis
̶ Specialized complementary examinations – cardiology, neurology,….
20Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno27
Possibilities of genetic testing 1
̶ Modern methods allow for parallel analysis of a group of patients and dozens or hundreds of genes, or even wholeexome
or whole-genome analysis.
̶ This can be utilized for diagnosing heterogenous diseases or extremely rare diseases in one go. However, the
development of molecular biology methods also necessitates a comprehensive approach to interpreting the vast
amount of data obtained. The conclusions (classifications) are not always clear-cut and require further "in silico"
analyses, functional experimental tests and collaboration with experts in bioinformatics.
̶ The classification of individual variants may not be permanent and is associated with the current level of knowledge in
the field. The clinical application of this data is gradual and much slower and may change over time. This leads to the
necessity of repeated analyses of previously addressed diagnoses and their updates in light of new findings, placing
additional demands on physicians across all specialties as well as clinical geneticists, molecular biologists, and
bioinformaticians.
In this regard, not only the patient’s attending physicians but also the patient and their family must be informed
21Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno28
Possibilities of genetic testing 2
̶ The diagnostic process may not be a one-time thing, it can be a long-term process that
may yield conflicting results over time.
̶ A large number of genomic sequence variants need to be processed and correctly
interpreted.
̶ It is necessary to consider the potential impact of information obtained through modern
diagnostic methods in medical genetics on the patient, their physician, the clinical
geneticist and the molecular biologist.
̶ Extensive laboratory genetic testing using modern methods creates a large and complex
issue of random incidental findings
-> What should be reported? (to the clinical geneticist, the specialist physician, the patient)
22Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno29
Possibilities of genetic testing 3
̶ Before laboratory genetic testing, the risc of incidental findings related to genetic
predispositions must be discussed with patient during genetic counseling.
̶ These incidental or unexpected findings, which can arise particularly from gene panel
analyses and whole-genome sequencing, but also molecular-cytogenetic methods,
such as array-CGH, may not be related to the condition for which the patient/family is
primarily being tested, but can have significant consequences for the individual
carrying the predisposition.
̶ Highlights importance of genetic counseling and informed consent.
23Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno30
Legislation
̶ Act No. 372/2011: Act on Health Services and Conditions for Their
Provision (Health Services Act)
̶ Act No. 373/2011: Act on Specific Health Services
̶ Convention on Human Rights and Biomedicine of 1996 (No. 96/2006
Coll.)
̶ Recommendations of proffesional associations– in CZ www.slg.cz
24Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno31
Act No. 373/2011 on Specific Health Services, Section 6, §28
̶ "Knowledge of basic genetic principles is an indisputable necessity for physicians of any specialization.
Collaboration between clinicians from all medical fields and clinicians specializing in medical genetics is a
standard practice in modern medicine, as established by Czech legislation:
̶ 'If a genetic laboratory test is expected to provide a diagnostic conclusion with a significant medical impact on
the health of an embryo, fetus, or the examined individual, including future generations, or on the health of
their genetically related individuals, the healthcare provider must always recommend genetic counseling by a
physician with specialized qualifications in the field of medical genetics, both before and after the examination.
̶ Genetic counseling, according to the preceding sentence, should be recommended to the parents of the
embryo or fetus, the legal guardian or representative of the examined individual, the examined individual, and
affected genetically related persons.
̶ If the goal of the genetic laboratory examination is the analysis of somatic (X germinal) changes in the human
genome, it is not necessary to conduct genetic counseling by a physician with specialized qualifications in the
field of medical genetics.'
25Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno32
Genetic prognosis
̶ Consultation with a Clinical Geneticist:
Establishing an accurate clinical diagnosis (in collaboration with other specialists)
Confirming the clinical diagnosis at the "Molecular level" (cytogenetic analysis, DNA analysis)
̶ Genetic Prognosis for the Family:
Is there a risk of recurrence of the same disease in the family?
Which relatives are at risk of recurrence of the same disease?
Which relatives should be advised to seek genetic counseling and genetic testing?
Can we reduce the risk of recurrence in the family? How?
̶ Genetic Prevention:
Non-directive approach – offering the family options for testing
Provide maximum information
The family always chooses the course of action; the geneticist informs and helps implement it
26Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno33
Prevention in medical genetics
Primary
&
Secondary
Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno34
Primary genetic prevention 1
= Preventive measures before (ideally planned)
pregnancy
• Genetic counseling
• Reproduction at an optimal age
• Prevention of spontaneous and induced mutations
• Vaccination against rubella, prevention of other infections
(e.g., toxoplasmosis)
• Preconception and periconception care
• Vitamin prevention of cleft defects
28Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno35
Primary genetic prevention 2
= Preventive measures before (ideally planned)
pregnancy
• Preconception consultation with a primary care physician or
specialist
• Evaluation of acquired chromosomal aberrations
• Contraception
• Sterilization
• Adoption
• Gamete donation
29Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno36
Secondary genetic prevention
= Procedures during pregnancy – prenatal diagnosis
= Early postnatal diagnosis
30Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno37
Secondary genetic prevention 2
•Genetic counseling
•Prenatal screening for congenital defects and chromosomal
abnormalities
•Targeted invasive and non-invasive prenatal diagnosis
•Preimplantation genetic diagnosis
•Prenatal and perinatal management of pregnancy with
identified developmental defects or hereditary diseases
•Prenatal therapy - if possible
31Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno38
Secondary genetic prevention 3
•Termination of pregnancy
•Postnatal screening
•Presymptomatic screening
•Preclinical prevention of clinical manifestation of
hereditary disease
•Postnatal examination, testing, care, and therapy
•Retrospective genetic counseling
32Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno39
Prenatal Diagnosis
Set of procedures aimed at identifying
statistically significant deviations in structure
or function that exceed the boundaries of
phenotypic variability.
Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno40
Prenatal diagnosis of congenital defects
and hereditary diseases allows for early
detection with possibility to plan optimal
perinatal care in advance.
In severe cases, it may lead to the early
termination of pregnancy.
Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno41
Prenatal diagnosis
•Screening tests – for all pregnant women
•X
•Targeted tests – in cases of increased risk of disease/defect
in the fetus
•Non-invasive prenatal testing
•X
•Invasive prenatal testing
Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno42
Non-invasive prenatal testing - methods
Ultrasound examination
Biochemical testing
Testing of cell-free fetal DNA in maternal plasma (NIPT/NIPS)
• Fetal aneuploidy
• Fetal microdeletion syndromes
• Fetal Rh factor
• Determination of fetal sex (XX, XY)
• Certain monogenic diseases in the fetus
36
Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
Screening
Screening means the process of sorting.
Screening in medicine involves examining a predefined
group of people to detect diseases in their
early stages, before the patient has symptoms or
problems
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Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
Screening during pregnancy
I. Trimester (10-14 weeks gestation):
- NT (Nuchal Translucency): Measurement of the nuchal translucency at the back of
the fetus's neck (ultrasound)
- NB (Nasal Bone): Presence of the nasal bone in the fetus (ultrasound)
- PAPP-A (Pregnancy-Associated Plasma Protein A (biochemical test)
- Free β-hCG (Free Beta Subunit of Human Chorionic Gonadotropin): A hormone
measured in the blood (biochemical test)
Combined Screening: Combines ultrasound and biochemical tests
II. Trimester (16-18 weeks gestation)
- AFP (Alpha-Fetoprotein)
- Total hCG (Total Human Chorionic Gonadotropin)
- uE3 (Unconjugated Estriol)
Biochemical Screening: Blood test of the pregnant individual
Integrated Screening: Evaluates individual risk based on parameters from both the
first and second trimester screenings
- NT + PAPP-A + AFP + Total hCG + uE3
38 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
What Screening during pregnancy good for?
For screening pregnancies with an increased risk,
primarily for Down syndrome, and potentially for
Edwards syndrome, Patau syndrome, neural tube
defects (NTDs), and Smith-Lemli-Opitz syndrome
(SLOS, autosomal recessive) in the fetus.
39 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
Comparison of Detection Rates (DR) for different screening
methods for trisomy 21 at a 5% false positive rate (Nikolaides).
Screening method DR in %
Maternal Age (MA) 30
MA and biochemical screening (maternal serum) at 15-18
weeks gestation
50-70
MA and fetal nuchal translucency (NT) measurement at 11-
13+6 weeks gestation
70-80
MA and fetal NT measurement along with free β-hCG and
PAPP-A in maternal serum at 11-13+6 weeks gestation
85-90
MA and fetal NT + nasal bone (NB) measurement at 11-
13+6 weeks gestation
90
MA and fetal NT and NB measurement, along with free βhCG
and PAPP-A in maternal serum at 11-13+6 weeks
gestation
95
40 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
Impact of Maternal Age and Gestational Age
(Nikolaides)
- The risk of trisomy increases with maternal age.
- The risk of Turner syndrome and triploidy does not change with
maternal age.
- The risk of chromosomal abnormalities is highest in the early stages
of gestation.
- The mortality rate for fetuses with trisomy 21 between the 12th week
(when NT is performed) and the 40th week of gestation is
approximately 30%.
- The mortality rate for fetuses with trisomy 21 between the 16th week
(when biochemical serum screening is conducted in the second
trimester) and the 40th week is approximately 20%.
- For trisomies 18 and 13 and Turner syndrome, the fetal mortality rate
between the 12th and 40th weeks of gestation is approximately 80%.
41
Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
Ultrasound Screening: Three-Step Process
- 12th + 20th + 33th week of gravidity
• Detection of detectable developmental abnormalities
• Detection of detectable cardiac defects
• Detection of indirect signs of chromosomal abnormalities
• Monitoring of fetal growth and development
• Signs of certain monogenic disorders:
• Shortened limb bones: Small stature, increased risk of
conditions such as achondroplasia
• Increased echogenicity of intestinal loops: Increased risk of
cystic fibrosis in the fetus
42 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
Ultrasound Screening
First Trimester Ultrasound Screening (10-13 weeks gestation):
Information on:
- Number of fetuses
- Size + length of pregnancy
- Nuchal translucency
- Presence of the nasal bone – risk assessment for Down syndrome
- Detection of risk for certain congenital developmental defects
Second Trimester Ultrasound Screening (20 weeks gestation):
Examination focused primarily on:
- Detection of detectable congenital developmental abnormalities
- Indirect signs of congenital chromosomal abnormalities in the fetus
43 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
US Prenatal Cardiology at 20-22th week of gestation
- detection of detectable cardiac defects
- Congenital heart defects are the most common developmental
abnormalities in humans and are often associated with additional
disorders/defects.
- Prenatal diagnosis of congenital heart defects requires specialized
expertise and experience, typically performed by pediatric
cardiologists and specialists in prenatal cardiology.
- Identifying a heart defect in the fetus allows for modifying
subsequent management based on the severity of the condition,
including options such as termination of pregnancy, fetal
treatment, monitoring and delivery at a specialized center where
…cardiological or cardiac surgical treatment for the newborn is
…available
44 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
NIPT (Non-Invasive Prenatal Testing)
Genetic testing of Free fetal DNA in maternal plasma (originating from
the placenta):
- Detection of trisomy 21 (Down syndrome), and potentially trisomy 18 and
13, sex chromosome aneuploidies, analysis of triploidy, and possibly
microdeletion syndromes
- Performed after the 10th-11th week of pregnancy
- Currently not covered by medical insurance due to relatively high cost
- High reliability of 98-99%
- A pathological finding must be confirmed with invasive testing
Other uses:
- Fetal RhD status determination
- Fetal sex determination (detection of SRY for X-linked diseases)
- Monogenic hereditary diseases in the fetus – currently available for some
conditions (e.g., achondroplasia with single mutation scoring)
- Autosomal recessive (AR) hereditary diseases? De novo mutations?
45 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
Invasive prenatal testing
• CVS (Chorionic Villus Sampling) – Collection of chorionic
villi (11-14 weeks gestation)
• AMC (Amniocentesis) – Collection of amniotic fluid (16-20
weeks gestation)
• Cordocentesis – Collection of fetal blood from the umbilical
cord (after 20 weeks gestation)
• Placenta Sampling (Placental Biopsy) – Collection of
placental tissue (less commonly used, may be referred to as
placentocentesis)
46 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
Indications for Invasive Prenatal Diagnosis
- Pathological result from combined/biochemical/integrated screening
- Pathological ultrasound finding in the fetus
- Carrier status of a balanced chromosomal abnormality in parents
- Congenital chromosomal abnormality in the family or in a previous
pregnancy
- Monogenic hereditary disease in the family
- Advanced parental age (?)
(women over 35 years old, combined age of partners over 70-75 years,
….men over 45 (?) years old - new mutations like achondroplasia,
….neurofibromatosis)
47 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
Prenatal Testing for Chromosomal Abnormalities
• QF-PCR (QuantitativeFluorescent Polymerase Chain Reaction):
Tests for the most common chromosomal numerical abnormalities of chromosomes 13, 18, 21,
X, and Y (and possibly chromosomes 15, 16, 22, which are common aneuploidies in miscarried
fetuses). Results available within 24-48 hours.
• Karyotyping:
Basic genetic test, essential for assessing structural chromosomal abnormalities (e.g., balanced
translocations in parents).
• Array-CGH (Array Comparative Genomic Hybridization):
Used when there are pathological ultrasound findings and is increasingly used for all patients.
48
55 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
Prenatal Diagnosis of Monogenic Disorders
̶ Based on preconception genetic testing or specific ultrasound findings (e.g.,
increased echogenicity of bowel loops suggesting cystic fibrosis, shortening of limb bones indicating
achondroplasia).
̶ Usually involves scoring of familial or in population frequent pathogenic variants, rarely
NGS panel testing due to time factor
̶ Invasive Testing During Pregnancy:
̶ CVS (Chorionic Villus Sampling): Performed after 10 weeks of gestation.
̶ Amniocentesis (AMC): Performed after 15 weeks of gestation.
̶ Cordocentesis: Performed after 20 weeks of gestation.
̶ Material for Testing:
̶ Chorionic villi or amniotic fluid cells. Testing can be done immediately or after sample cells cultivation;
rarely, fetal blood is used.
̶ Contamination with Maternal Tissue:
̶ Always needs to be excluded, particularly with CVS and amniotic fluid samples without culture.
In families with known risk of a monogenic disorder, it is recommended to consider
Preimplantation Genetic Diagnosis (PGD) as part of In Vitro Fertilization (IVF).
49
56 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
Preimplantation Genetic Diagnosis (PGD)
̶ PGD is an early prenatal diagnostic method that is associated with assisted
reproductive techniques.
̶ PGD is a method that allows the detection of genetic abnormalities in an embryo by
examining a few cells taken from the developing embryo. Only embryos without
genetic defects can be selected for transfer into the uterus.
̶ Before performing PGD, we recommend preconception genetic testing and
karyotype analysis of the partners, as well as DNA analysis of the parents in cases of
monogenetic hereditary diseases.
̶ This method allows at-risk couples to have an unaffected child without the need to
rely on traditional prenatal diagnostics, which may involve making decisions about
terminating the pregnancy.
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57 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
Preimplantation Genetic Diagnosis (PGD)
VS
Preimplantation Genetic Screening (PGS) for Aneuploidies
̶ PGD – Testing for couples with a high genetic risk of disease in
the fetus – carriers of translocations or predispositions for
monogenic inherited diseases (PGT-Structural, PGT-Monogenic).
̶ PGS – Screening of common aneuploidies, where the risk is
increased due to age or an unfavorable reproductive history
(PGT-A).
51
59 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
PGS / PGD
̶ Alternative to prenatal diagnosis
̶ Prevention of abortions indicated based on results of invasive prenatal
diagnosis
̶ Preventive and targeted diagnosis of specific genetically determined diseases
̶ Embryo selection for IVF in couples at risk of genetic disease
̶ Today, testing usually involves 6-8 cells of the embryo on day 5 after IVF
(previously one or two blastomeres on day 3)
52 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
Prenatal and perinatal management of
pregnancy with diagnosed developmental
disorders or genetic diseases in the fetus
53 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
̶ Consultation with specialists who will continue to care for the pregnant
woman: ultrasound specialists, geneticists, gynecologists, psychologist etc.
̶ Determination of the most accurate diagnosis and prognosis, and exclusion of
combinations with other conditions, etc.
̶ Consultation with specialists who will care for the newborn with a condition
after birth.
̶ Planned delivery at a facility with specialized care (cardiac center, pediatric
surgery, cardiology, etc.).
Genetic indication for interruption
Law of the Czech National Council No. 66/1986
on Induced Termination of Pregnancy, Decree
of the Ministry of Health No. 75/86:
Paragraph 2
* After the 12th week of pregnancy, an abortion
can only be performed if the woman's life is in
danger, or if severe fetal damage is proven, or if
the fetus is unviable.
* If there are genetic reasons for an abortion, it can
be performed up to the 24th week of pregnancy.
Genetic Reasons:
- Severe hereditary diseases or congenital
anomalies diagnosed in the fetus through
prenatal diagnostic methods or evidence of
their high risk.
- Risk of serious hereditary disease or
anomaly determined by genetic testing
exceeding 10%.
- Factors with proven teratogenic or
mutagenic effects on the fetus.
54 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
Problems - Conflicts
Prenatal diagnosis does not detect all diseases
Successfully ruling out certain serious conditions through
targeted prenatal diagnosis does not guarantee that the
baby will be free from other severe diseases. There is
always a risk that the child could be born with a different,
unrelated serious condition.
55 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
Ethical aspects Recommendations
64 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
̶ Equal access to prenatal diagnostics, fair
distribution
̶ Voluntariness
̶ Offering prenatal diagnostics not conditional
on terminating the pregnancy
̶ Only severe health indications
̶ Psychological indications are not a priority
̶ Genetic counseling precedes
̶ Communication of all relevant information
̶ Family decision is protected and
respected
̶ Ensuring safe termination of pregnancy
̶ Supportive counseling after pregnancy
termination
Genetic counseling and genetic testing in
reproductive disorders
̶ Is fertility disorder a result of a genetic disorder that could
be passed on to the next generation?
̶ Can fertility correction increase the risk of malformations,
diseases, and chromosomal abnormalities in offspring?
̶ Can genetic testing and prenatal diagnostics reduce this
risk?
57
65 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
Couples with Reproductive Disorders Indications
for Genetic Testing
̶ More than 1 year of unsuccessful attempts to conceive
with regular intercourse
̶ 2 or more spontaneous miscarriages
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66 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
Genetic Causes of Reproductive Disorders
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̶ Congenital chromosomal abnormalities
̶ Monogenic hereditary diseases
̶ Congenital malformations, multifactorial hereditary diseases
̶ Increased tendency to spontaneous abortions due to thrombophilia
̶ Disorders of spermatogenesis based on genetic disorders
Genetic Testing for Patients with Reproductive
Disorders
̶ Genetic Counseling - Genealogy, Medical History
̶ Cytogenetic Examinations:
- Karyotyping (for all patients with reproductive disorders)
- Acquired chromosomal abnormalities (e.g., due to risky work environments,
….cytostatic treatments in medical history, etc.)
̶ Molecular Genetic Testing
̶ CFTR Gene – family burden (e.g., unexplained child deaths, repeated lung or
middle ear infections), prevention in cases of recurrent miscarriages or multiple
unsuccessful IVF cycles, men with abnormal sperm analysis.
̶ Thrombophilic Mutations (e.g., Leiden mutation - factor V, Prothrombin factor II G20210A)
- women with recurrent spontaneous abortions and fetal losses.
̶ Yp AZF Regions a, b, c – men with severe oligospermia and azoospermia (sperm
count ≤ 5 million/ml).
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68 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno
Congenital chromosomal abnormalities occur with a
population frequency of 0.6%.
In individuals being evaluated for reproductive
disorders, the risk is reported to be approximately 10
times higher (6-7%).
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Thrombophilic mutations
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̶ Increase congenital risk for deep vein thrombosis, sudden ischemic vascular events, and
embolisms even at a young age, as well as an increased risk of recurrent fetal losses,
intrauterine growth restriction (IUGR), placental infarcts, HELLP syndrome, and stillbirths –
Factors V and II
Leiden mutation G1691A (Factor V)
̶ Frequency in the white European population is approximately 5-9%.
̶ Autosomal dominant inheritance.
̶ Increases the risk of thromboembolism: 50-100 times for homozygotes, 5-10
times for heterozygotes.
̶ Association with the risk of early fetal losses is not confirmed.
̶ Increases the risk of fetal losses from the end of the first trimester and in the
second and third trimesters.
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G20210A variant in Prothrombin (Factor II)
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̶ The mutation is found in about 2-3% of the population in a heterozygous state.
̶ Increases the risk of thromboembolism.
̶ Carriers are associated with an increased risk of fetal losses, placental abruption,
preeclampsia, and intrauterine growth restriction (IUGR).
̶ The risk of early spontaneous abortions (SAs) is not confirmed.
Male Infertility
̶ Oligoastoenozoospermia – Azoospermia
̶ Chromosomal Abnormalities
̶ Microdeletions Yq11.23 – DAZ Gene – AZF Region: DAZ
(Deleted in Azoospermia) gene is deleted in cases of
azoospermia.
̶ CFTR Gene: Mutations, including the 5T allele in the noncoding
region of intron 9, are associated with Congenital
Bilateral Absence of the Vas Deferens (CBAVD).
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CFTR gene
̶ Carriers of mutations and certain polymorphisms experience sperm production
disorders (5T – CBAVD).
̶ Cystic fibrosis can be a cause of male sterility in patients
̶ Carrier Frequency: In the general population, 1 in 27 individuals is carrier; among
men with abnormal sperm analyses (SPG), the carrier rate is 1 in 19 (possibly
symptomatic heterozygotes?).
̶ Most common monogenic disorder: Preventive testing is recommended before IVF,
after recurrent miscarriages (SA), or following unsuccessful IVF attempts.
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Microdeletions in AZF regions a, b, c of the DAZ gene:
̶ Approximately 4-5% in infertile men and about 15-18% in cases
of azoospermia.
̶ When using IVF and micromanipulation techniques, there is a
risk of passing the reproductive disorder to sons.
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Genetic Testing in Couples with Reproductive Issues
̶ Genetic counseling provides partners with information on options of genetic testing
and the implications of the results for them and their offspring
̶ Targeted Basic Genetic Testing:
- Karyotyping both partners, possibly performing Array-CGH
- Testing for thrombophilia in women with recurrent miscarriages.
- Testing for CFTR gene mutations and microdeletions in AZF regions a, b, c of the
…..DAZ gene, and other relevant genes in men with abnormal sperm parameters.
̶ Extended preventive couples testing
- screening for carrier status of autosomal recessive (AR) and X-linked (XR)
….disorders - „Carrier test“
̶ Recommendations based on abnormal/pathological findings
- targeted prenatal or preimplantation genetic diagnosis
- preventive testing of relatives at risk
Preventive Genetic Testing for Gamete Donors
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̶ Donors medical history
̶ Three-Generation Family Pedigree: Identification of genetic family history
(developmental disorders, hereditary diseases, reproductive issues).
̶ Karyotyping: Determination of chromosomal structure and identification of
abnormalities.
̶ CFTR Gene Carrier Screening: Analysis for carriers of common mutations
associated with cystic fibrosis.
̶ SMA Carrier Screening: Analysis for carriers of mutations associated with spinal
muscular atrophy.
̶ Carrier Screening for Non-Syndromic AR Hearing Loss: Analysis for carriers
of mutations in the GJB2 gene, associated with autosomal recessive hearing loss.
̶ Extended DNA Analysis: Panel testing for common recessive hereditary
disorders to identify potential genetic risks.
Neonatal screening
̶ Neonatal screening is active, nationwide detection of diseases in
their preclinical stage in newborns.
̶ Analysis of a dried blood spot on filter paper, collected in the standard
way from the heel of the newborn.
̶ Founder: Prof. Robert Guthrie (1916-1995).
̶ Phenylketonuria screening in the USA since 1963.
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Neonatal screening until 10/2009
̶ Phenylketonuria
̶ Congenital hypothyroidism
̶ Congenital adrenal hyperplasia
̶ Orthopedic examination for hip dislocation
̶ Screening for congenital cataracts
̶ Screening for hearing impairment
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Neonatal screening
̶ Bulletin of the Ministry of Health of the Czech Republic No. 6/2009
Expanded newborn screening from 3 to 13 diseases starting from 10-12/2009
̶ Bulletin of the Ministry of Health of the Czech Republic No. 6/2016
Methodological guide for ensuring newborn screening and follow-up care (pages 2-11),
Issued on May 31, 2016, effective from June 1, 2016
Expansion to include 5 additional diseases
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Diseases Screened Since October 2009
̶ Endocrine diseases – Congenital hypothyroidism, Congenital adrenal
hyperplasia (CAH)
̶ Inherited metabolic disorders – Phenylketonuria (PKU, HPA), Leucinosis,
MCAD, LCHAD, VLCAD, Deficiency of carnitine palmitoyltransferase I and II,
Deficiency of carnitine-acylcarnitine translocase, Glutaric aciduria, Isovaleric
aciduria…
̶ Others – Cystic fibrosis
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Diseases Screened Since October 6/2016
̶ Endocrine diseases – Congenital hypothyroidism, Congenital adrenal hyperplasia (CAH)
̶ Inherited metabolic disorders (IMD): Argininemia (ARG), Citrullinemia Type I (CIT), Medium-chain acyl-CoA
dehydrogenase deficiency (MCAD), Very long-chain acyl-CoA dehydrogenase deficiency (VLCAD),
Biotinidase deficiency (BTD), Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHAD), Carnitine
palmitoyltransferase I deficiency (CPT I), Carnitine palmitoyltransferase II deficiency (CPT II), Carnitineacylcarnitine
translocase deficiency (CACT), Phenylketonuria (PKU) and hyperphenylalaninemia (HPA),
Glutaric aciduria Type I (GA I), Homocystinuria due to cystathionine beta-synthase deficiency (CBS),
Homocystinuria due to methylenetetrahydrofolate reductase deficiency (MTHFR), Isovaleric aciduria (IVA),
Maple syrup urine disease (MSUD)
̶ Other – Cystic fibrosis
̶ Cumulative risk of all screened diseases: 1 in 1200
̶ www.novorozeneckyscreening.cz
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Samples for Newborn Screening
̶ Blood sampling for newborn screening can only be performed with the consent of the
newborn’s legal guardian.
̶ An overview of information for legal guardians and a sample informed consent form for
newborn screening are provided in Appendix 1 of the Methodological Guideline.
̶ If the informed consent is in written form, the healthcare provider must store it in the medical
documentation of the newborn.
̶ If the legal guardian of the newborn refuses to have the newborn screening performed, this
refusal must be documented in writing in the medical documentation of the newborn.
̶ The recommended form for recording the refusal of newborn screening is provided in
Appendix 2 of the Methodological Guideline.
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Newborn screening Conditions
for the disposal of cards/samples of DNA
̶ Disposal of Screening Cards
For blood collection, double self-copying screening cards are used (referred to as screening
cards). Providers who have performed the laboratory screening tests retain these cards for five
years, with shredding conducted under S5 conditions.
̶ Disposal of DNA Samples for Newborn Screening
In the case of analyzing hereditary changes in the CFTR gene, DNA isolated from the
screening card is disposed of within 2 months after the test is completed.
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Postnatal Genetic Testing
̶ Early diagnosis
-> Monitoring
-> Specialized care
-> Interdisciplinary collaboration
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Presymptomatic Testing
̶ diseases with late onset of symptoms
̶ hereditary cancer disorders
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Preventive programs
̶ Consultation with a clinical geneticist, creation of a three-generation family tree based on medical
history
̶ Karyotype analysis
̶ Analysis of acquired chromosomal abnormalities
̶ Testing for cystic fibrosis carrier status (carriers in the Czech Republic approximately 1/30-40)
̶ Testing for spinal muscular atrophy carrier status (carriers in the Czech Republic approximately
1/60-80)
̶ Testing for the most common cause of autosomal recessive non-syndromic hearing loss (GJB2
gene)
̶ Testing for carrier status of other common autosomal recessive and X-linked inherited diseases
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If you have any questions, you can contact me by email at:
soukalova.jana@fnbrno.cz
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88 Institute of Medical Genetics and Genomics Faculty of Medicine of Masaryk University and University Hospital Brno