[Clinical and molecular genetic analysis of a patient with 3-M syndrome].

Objective To analyze the clinical features and molecular genetic etiology of a patient with 3-M (Miller McKusick Malvaux) syndrome from a consanguineous parentage family, and to explore the relationship between genotype and phenotype. Methods After the consent of the proband's guardian and the informed consent form was signed, DNA was extracted from peripheral blood samples of the proband and her parents for chromosome microarray analysis, medical exome sequencing and parental verification. Results A total of 247.1 Mb loss of heterozygosity was found in the proband with a CytoScan 750K array. Furthermore, a homozygous variant (c.458dupG) of the OBSL1 gene was found using high-throughput sequencing, which was inherited from her parents. Based on the criteria and guidelines of genetic variation of American College of Medical Genetics and Genomics, the variant is predicted to be pathogenic (PVS1+PM2+PP4), and only one case was reported previously. Conclusion Spina bifida occulta and lower eyelid fat pad may be a special phenotype of c.458dupG variant of the OBSL1 gene. Our study may provide a useful reference for evaluating the relationship between genotype and phenotype of 3-M syndrome type 2.