The average incidence of Patau syndrome is estimated to be 1:5,000 newborns. Free trisomy 13 is detected in 75%, mosaic trisomy in 5%, and an unbalanced translocation in 20%. The characteristic external abnormalities include a usually bilateral cleft lip and palate, various eye defects (microophthalmia, anophthalmia, coloboma), microcephaly, hexadactyly, ear dysplasia, scalp defects, and omphalocele. Organ malformations include heart defects and cystic kidneys and CNS anomalies such as arhinecephaly or holoprosencephaly. Psychomotor development is severely impaired. About 50% of the patients die within the first month of life and more than 90% within the first year of life.
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