A case report of Chung-Jansen syndrome

Abstract

Global developmental delay (GDD) has a wide range of underlying causes, and advances in genetic testing, particularly whole exome sequencing (WES), have improved diagnostic accuracy. Chung–Jansen syndrome is a rare neurodevelopmental disorder caused by variants in the PHIP gene and is characterized by developmental delay, intellectual disability, hypotonia, and behavioural abnormalities. We report a 6-year-old girl with global developmental delay, hypotonia, and inattention. She had delayed motor and speech milestones along with progressive cognitive decline. Examination revealed generalized hypotonia, mild distal weakness, bilateral ptosis, and refractive error. WES identified a heterozygous missense variant in the PHIP gene, classified as a variant of uncertain significance (VUS). The clinical presentation showed partial overlap with Chung–Jansen syndrome. The child is on multidisciplinary supportive therapy. Genetic counselling and parental testing were advised. This case highlights the importance of WES in unexplained GDD and the need for clinic genetic correlation when interpreting VUS.