Variable expressivity in Patau syndrome is not all related to trisomy 13 mosaicism

Trisomy 13 is very rare in live-born children. Only a small number of these children survive the first year and very few cases are reported to live longer. Survival time depends partly on the cytogenetic findings--full trisomy 13 or trisomy 13 mosaicism--and partly on the existence of serious somatic malformations. We report on a 11-year-old girl with full trisomy 13. In this case, missing cerebral and cardiovascular malformations probably allowed the long survival.