Female-restricted syndromic intellectual disability in a patient from Thailand

Female-restricted syndromic intellectual disability (ID) is a neurodevelopmental disorder with developmental delay (DD)/ID, facial dysmorphism, and diverse congenital anomalies comprising heart defects, anal anomalies, choanal atresia, postaxial polydactyly, scoliosis, and brain abnormalities. Loss-of-function mutations in the USP9X gene inherited as X-linked dominance were identified as its etiology in females of different ethnic groups. Here, we report a 15-year-old Thai girl harboring a novel de novo heterozygous one-base pair deletion (c.3508delG, p.Val1170TrpfsX9) in exon 23 of USP9X. Her profound DD, dysmorphic face including attached earlobes, short stature, and congenital malformations including s-shaped thoracolumbar scoliosis, hip dislocation, and generalized brain atrophy shared common characteristics of X-linked syndromic ID. We have observed severely malformed oro-dental organs and a choledochal cyst, which have never been reported. Our study presents the first patient from Thailand expanding the phenotypic and mutational spectra of the syndrome.