Abstract:

Objective To identify the genetic causes of four patients with different severity of congenital skeletal disorder by genetic diagnosis, and to summarize the clinical characteristics and analyze the genotype-phenotype. Methods The clinical data of four patients were collected. The peripheral blood of the patients and their parents were collected and DNA was extracted. Whole exome sequencing of patients was performed and variants were classified following the interpretation standards and guidelines of the American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology. Putative pathogenic variants were verified by Sanger sequencing. Results The four patients all carried TRPV4 heterozygous variants. Two missense variants were inherited from affected parents, and one deletion insertion variant and missense variant were de novo: c.2077G>A (p.Val693Met), c.1199G>A (p.Arg400Gln), c.1657delinsACTA (p.Tyr553delinsThrAsn) and c.259G>A (p.Glu87Lys). None of these variants have been previously reported. Patients 1-3 had varying degrees of short stature, and all 4 had congenital scoliosis and other skeletal deformities. They were diagnosed as mild Metatropic Dysplasia, Autosomal Dominant Brachyomia type 3, Parastremmatic Dysplasia with Metatropic Dysplasia, and classic Metatropic Dysplasia respectively. Their parents with the same variant also had mild bone deformity. Conclusions The phenotypes of congenital skeletal disorders caused by different variants in TRPV4 gene were widely heterogeneous. Patients often present with overlapping skeletal system abnormalities. Therefore, differential diagnosis and clinical intervention can be conducted according to the molecular diagnosis results.

Key words: TRPV4 gene, congenital skeletal disorder, genotype-phenotype, molecular diagnosis