A Novel Homozygous Variant of in a Case With Hypoplasia of the Cerebellar Vermis and Polydactyly.

Transmembrane protein 231 (TMEM231) is a component of the B9 complex that participates in the formation of the diffusion barrier between the cilia and plasma membrane. Mutations in gene may contribute to the Joubert syndrome (JBTS) or Meckel-Gruber syndrome (MKS). However, reports on JBTS or MKS caused by mutations are comparatively rare. We describe a Chinese fetus with unexplained hypoplasia of the cerebellar vermis and polydactyly, detected by ultrasound imaging. The fetus was primarily diagnosed with JBTS/MKS. The parents of this fetus were non-consanguineous and healthy. Whole-exome sequencing (WES) and bioinformatics strategies were employed to explore the genetic lesion of this family. An unknown missense variant (c.19C>T;p.R7W) of gene was detected. The variant was predicted as pathogenic and was absent in our 200 healthy controls. WES was employed to explore the genetic lesion of a fetus with unexplained hypoplasia of the cerebellar vermis and polydactyly. A novel variant in gene was identified. Our study not only provided data for genetic counseling and prenatal diagnosis to this family but also broadened the spectrum of mutations.