Analysis of genetic variant in a child with Pitt-Hopkins syndrome

Abstract

To explore the genetic basis for a child featuring facial dysmorphism, single palmar crease, motor and language delay, and hypoplasia of corpus callosum. A child who had visited the Affiliated Hospital of Binzhou Medical College on March 16, 2021 was selected as the study subject. Peripheral blood samples of the child and his parents were collected, and the genomic DNA was extracted for whole exome sequencing (WES). Candidate variant was verified by Sanger sequencing and bioinformatic analysis. WES revealed that the child has harbored a heterozygous c.607delT (p.S203Pfs*31) variant in exon 9 of the TCF4 gene, for which both of his parents were of the wild-type. Based on guidelines from the American College of Medical Genetics and Genomics, the variant was classified as pathogenic (PVS1+PM2_Supporting+PM6). The heterozygous c.607delT (p.S203Pfs*31) variant of the TCF4 gene probably underlay the Pitt-Hopkins syndrome in this child. Genetic testing has enabled the definite diagnosis.