Snapshot A 40-year-old woman gave birth to a girl at 39 weeks gestation. She had been lost to follow-up after her first prenatal appointment, and reports that she felt well during the pregnancy. The neonate born has significant cleft lip and cleft palate and microcephaly. An ultrasound shows ventricular septal defect of the heart as well as cerebral malformations. The neonate passes away a few hours later. The pediatrician informs the family that this child likely had an autosomal trisomy disorder. Introduction Overview Patau syndrome is an autosomal trisomy disorder of chromosome 13 characterized by severe intellectual disability and characteristic facial features, including cleft lip/palate, microcephaly, and microphthalmia Epidemiology Incidence 1 in 8,000-15,000 rarest and more severe of the autosomal trisomies Risk factors increased maternal age ETIOLOGY Genetics trisomy of chromosome 13 more rarely due to partial trisomy of chromosome 13 or translocation Associated conditions polycystic kidney disease congenital heart disease Presentation Symptoms severe intellectual disability holoprosencephaly brain malformation associated with severe neurological dysfunction brain does not divide into halves cardiac anomalies patent ductus arteriosus and septal wall defects are common Physical exam inspection cleft lip or cleft palate cutis aplasia on the scalp rocker-bottom feet polydactyly omphalocele hernias neural tube defects Imaging Fetal ultrasound indication abnormal aneuploidy screening or on routine ultrasonography findings growth restriction craniofacial defects and cerebral malformations cardiac anomalies Studies Genetic testing prenatal aneuploidy screening and/or prenatal ultrasound can often screen for Patau syndrome confirm with prenatal amniocentesis (15 weeks+ gestation) or chorionic villus sampling (10-12 weeks gestation) cytogenetic testing or fluorescent in-situ hybridization (FISH) Differential Viable Autosomal Trisomies Trisomy 13 Trisomy 18 Trisomy 21 Epidemiology Trisomy 13 is the least common viable trisomy It is also the most severe Trisomy 21 is the most common viable trisomy Trisomy 21 is the most common viable trisomy Prognosis Death by age 1 Death by age 1 Normal prognosis First trimester serum markers ↓ β-HCG ↓ PAPP-A ↓ β-HCG ↓ PAPP-A ↑ β-HCG ↓ PAPP-A Second trimester serum markers Normal ↓ Alpha fetoprotein ↓ β-HCG ↓ Estriol Normal/↓ inhibin A ↓ Alpha fetoprotein ↑ β-HCG ↓ Estriol ↑ Inhibin A Treatment Management approach there is no cure surgical options are typically deferred for the first few months of life as there is a high risk of mortality in that period Surgical surgical correction of anomalies indications highly dependent on infant’s survival and specific anomalies Complications Death Infections Malignancy Prognosis Many instances of Patau syndrome result in fetal demise Patients die by age 1 with median survival of 3 days There are reports of children surviving into teenage years Most common cause of death is cardiopulmonary arrest