Clinical and genetic characteristics of X-linked mental retardation 102 type caused by novel mutations in the DDX3X gene (OMIM:300958)

Abstract

Introduction. X-linked mental retardation 102 type caused by novel mutations in the DDX3X gene is one of the most common monogenic variants of intellectual deficiency in women.Purpose of the study. Description of the clinical and genetic characteristics of Russian female patients with type 102 mental retardation due to newly identified mutations.Materials and methods. The diagnosis of mental retardation of type 102 was established on the basis of the features of clinical manifestations and the detection of the mutations in the DDX3X gene as a result of exome sequencing and subsequent confirmation of the identified variants of Sanger sequencing.Results. A description is given of the clinical and genetic characteristics of two female patients with type 102 X-linked mental retardation due newly to identified mutations p.1703C> G and c.113A> G (NM_001193416) in the DDX3X gene in the heterozygous state. New features of the phenotype are described. The mechanism of the appearance of clinical and genetic correlations is suggested, which can be used as a prognostic marker of the development of the disease.Conclusion. Clinical and genetic characteristics of two patients with mutations in the DDX3X gene that violate the amino acid sequence of different protein regions with different severity of clinical manifestations are described. The results obtained may testify in favor of the existence of a dependence of the severity of the phenotype on the localization and nature of mutations in the gene and determine the relevance of further research aimed at searching for clinical and genetic correlations.