Prenatal Diagnosis of Tetrasomy 12P Mosaicism: A Case Report

Abstract

Tetrasomy 12p mosaicism (also Pallister–Killian syndrome or Pallister mosaic aneuploidy syndrome) is an extremely rare genetic disorder caused by the presence of two extra copies of the chromosome 12 short arm. The signs and symptoms vary, although most people with this disorder have severe to profound intellectual disability and other serious health problems. The ever reported anomalies include varying degrees of developmental disability, epilepsy, hypotonia, distinctive facial structure, characterized by a high, rounded forehead; a broad nasal bridge; a short nose; widely spaced eyes; low-set ears; rounded cheeks. Patients may also exhibit congenital heart defects, cataracts and diaphragmatic hernia. Case report and literature review. A 40 years old pregnant women, gravida3,para 2 had unremarkable medical history. The previous two pregnancies were uneventful. She received routine prenatal examinations in other local clinics and the report of non-invasive prenatal testing (NIPT) was low risk for trisom13,18 and 21 .She first came to our hospital when 24 weeks’ gestation for the fetal diaphragmatic hernia. The detailed ultrasound scan showed fetal left side diaphragmatic hernia, polyhydramnios (AFI:25cm), bilateral ventriculomegaly(1.04/1.06cm) and short long bones. The amniocentesis was then arranged for chromosome survey. The final report of karyotypes Giemsa banding was 47,XY,+i(12)(p10)[11]/46,XY[6] .No mutation defects were noted in the FGFR3 genes. The array-CGH showed a 33.99Mb-duplication at chromosome 12p12.33-12p11.1 and the report was arr[GRCh37]12p13.33p11.1(230,450- 34,217.,434)x4[0.78],(XY)x1. Tetrasomy 12p mosaicism is an extremely rare genetic disorder.The role of array CGH is important to make clear diagnosis when two or or more fetal anomalies were noted in the prenatal sonography.