First Chinese patient with mental retardation-40 due to a de novo CHAMP1 frameshift mutation: Case report and literature review.

Mental retardation-40 (MRD40) is a rare autosomal dominant neurodevelopmental disorder with a poor prognosis that is caused by a heterozygous mutation in chromosome alignment maintaining phosphoprotein 1 (CHAMP1). It was previously considered a non-syndromic disease due to the lack of specific external features. Only limited international reports describing CHAMP1 mutations are currently available. The present case study was the first to report on a Chinese patient with MRD40. The patient presented with severe global development delay with significant craniofacial dysmorphia. Using trio whole-exome sequencing, a novel de novo frameshift mutation in CHAMP1, NM_032436.2: c.530delCinsTTT, was identified, which expands the spectrum of the known pathogenic variants. The present case report helps to improve the syndromic profile of the rare MRD40 disorder and provides an example for the clinical diagnosis of MRD40.