Phenotypic variability in Patau syndrome

Patau syndrome has an incidence of 1/10.000-20.000, the clinical diagnosis being suggested by the triad cleft lip and palate, microphthalmia/anophthalmia and postaxial polydactyly. Most frequent cytogenetic abnormality is free and homogeneous trisomy 13 (80.0%), rarely being detected trisomy mosaics or Robertsonian translocations. The objective of the study was to identify phenotypic features of trisomy 13.

The retrospective study was conducted on a trial group of 14 cases diagnosed cytogenetically with trisomy 13 between January 2000 and December 2012 at lasi Medical Genetics Centre.

Of the 14 cases, 3 were evaluated pathologically (two aborted foetuses and one stillborn), 8 cases were detected in the neonatal period, and 3 in infancy. Clinical diagnosis was supported by the identification of a model of abnormal development, mainly characterized by: maxillary cleft (lip and palate--5 cases; lip--1 case), ocular abnormalities (microphthalmia/anophthalmia--7 cases; cyclopia--1 case), postaxial polydactyly (7 cases), scalp defects (6 cases), congenital heart anomalies (10 cases, 6 patients with atrial septal defect), complete holoprosencephaly (4 cases), ear abnormalities (11 cases), broad nasal root (10 cases). An important issue in confirming the phenotypic variability of Patau syndrome is that the classic clinical triad was identified only in one case.

Patau syndrome is a disease with variable expression and is characterized by a pattern of abnormal prenatal development characterized by facial dysmorphia, polydactyly and severe birth defects (heart, brain) that generate an increased in utero and perinatal mortality.