Genotype–phenotype characterization in 13 individuals with chromosome Xp11.22 duplications

Abstract

We report 13 new individuals with duplications in Xp11.22-p11.23. The index family has one male and two female members in three generations with mild-severe intellectual disability (ID), speech delay, dysmorphic features, early puberty, constipation, and/or hand and foot abnormalities. Affected individuals were found to have two small duplications in Xp11.22 at nucleotide position (hg19) 50,112,063-50,456,458 bp (distal) and 53,160,114-53,713,154 bp (proximal). Collectively, these two regions include 14 RefSeq genes, prompting collection of a larger cohort of patients, in an attempt to delineate critical genes associated with the observed phenotype. In total, we have collected data on nine individuals with duplications overlapping the distal duplication region containing SHROOM4 and DGKK and eight individuals overlapping the proximal region including HUWE1. Duplications of HUWE1 have been previously associated with non-syndromic ID. Our data, with previously published reports, suggest that duplications involving SHROOM4 and DGKK may represent a new syndromic X-linked ID critical region associated with mild to severe ID, speech delay +/- dysarthria, attention deficit disorder, precocious puberty, constipation, and motor delay. We frequently observed foot abnormalities, 5th finger clinodactyly, tapering fingers, constipation, and exercise intolerance in patients with duplications of these two genes. Regarding duplications including the proximal region, our observations agree with previous studies, which have found associations with intellectual disability. In addition, expressive language delay, failure to thrive, motor delay, and 5th finger clinodactyly were also frequently observed in patients with the proximal duplication.