stav, kdy jedinec nebo <span class="linked_term" onclick="showTermNamed('buňka')">*buňka</span> obsahuje jeden <span class="linked_term" onclick="showTermNamed('chromozom')">*chromozom</span> navíc. U&nbsp;<span class="linked_term" onclick="showTermNamed('člověk')">*člověka</span> jsou známé trizomie chromozomu 13 <span class="linked_term" onclick="showTermNamed('syndrom, Patauův')">*syndrom Patauův</span>, 18 <span class="linked_term" onclick="showTermNamed('syndrom, Edwardsův')">*syndrom Edwardsův</span>, 21 <span class="linked_term" onclick="showTermNamed('syndrom, Downův')">*syndrom Downův</span> a&nbsp;X <span class="linked_term" onclick="showTermNamed('syndrom 47,XXX')">*syndrom XXX</span>. (<span class="linked_term" onclick="showTermNamed('Relichová, Jiřina')">Jiřina Relichová</span>)