Whole exome sequencing and transcript analysis discover a novel pathogenic splice site mutation in DCAF17 gene underlying Woodhouse-Sakati syndrome

Abstract

Woodhouse-Sakati syndrome (WSS) is an extremely rare multisystemic disorder with neuroendocrine dysfunctions. It is characterized by hypogonadism, alopecia, diabetes mellitus, intellectual disability and progressive extrapyramidal syndrome along with radiological features of small pituitary gland, progressive frontoparietal white matter changes and abnormal accumulation of iron on globus pallidus. WSS is caused by mutations in DCAF17 gene that encodes for DDB1 and CUL4 associated factor 17. In this study, we report a 17-year-old boy with clinical and radiological features of WSS including mild global developmental delay, mild intellectual disability, sensorineural hearing loss, progressive extrapyramidal syndrome, alopecia, hypogonadotropic hypogonadism and dysmorphic features. Whole exome sequencing analysis revealed a novel potentially pathogenic splice donor site variant (c.458+1G>T) on the intron 4 of DCAF17 gene. Transcript analysis revealed splicing ablation resulting in aberrant splicing of exons 3 and 5 and skipping of exon 4 (c.322_458del). This results in a frameshift and is predicted to cause premature termination of protein synthesis resulting in a protein product of length 120 amino acids (p.[Gly108Ilefs*14]). Our study identified a novel pathogenic variant causing WSS in a patient and expands the spectrum of clinical and genetic characteristics of patients with WSS.

Keywords: NBIA; diabetes mellitus; low IGF-1; neuroendocrine disorder; splice defect.