Patau syndrome (trisomy 13) is very rare in live-born babies. Individuals with 
this chromosomal syndrome have a short lifespan and are rarely seen beyond 
infancy. This study is aimed at the clinical spectrum, natural history, and 
survival of patients with trisomy 13. We reviewed the detailed data of 13 Patau 
syndrome live-born babies. Among them two individuals were delivered from 
continuation of pregnancy even after prenatal diagnosis. The remaining 11 
patients were born to younger mothers who did not undergo amniocentesis because 
no major anomalies except for cleft lip/palate were found on prenatal sonograms. 
The common features of Patau syndrome including the clinical triad 
(microphthalmia, cleft lip/palate, and polydactyly) and non-cyanotic heart 
defects were always found in our series. However, certain serious central 
defects (holoprosencephaly, omphalocele, and single umbilical artery), which are 
easily recognized from prenatal sonogram, occurred less frequently than those 
stated in the literature. The median survival time was 95 days and was longer 
than that previously reported. There were two infants with trisomic mosaicism 
with different outcomes in both clinical spectrum and survival. Otherwise, we 
also found the increased recurrence risks of aneuploidy in two individuals, and 
the longest survivor (84 months) of non-mosaic trisomy 13 in Taiwan. We thus 
suggest that long-term survival in our series is strongly correlated with 
different expressivity after prenatal selection, in addition to cytogenetic 
mosaicism. Less associated anomalies such as polyhydramnios, oligohydramnios, 
intrauterine growth retardation, single umbilical artery, eye defects, 
holoprosencephaly, omphalocele, and polycystic kidney may contribute to their 
clinical courses.