A Novel Homozygous Nonsense Variant in the DYM Underlies Dyggve-Melchior-Clausen Syndrome in Large Consanguineous Family.

Genes 2023 Feb 17

filter terms:

1) Background: Dyggve-Melchior-Clausen Syndrome is a skeletal dysplasia caused by a defect in the DYM gene (OMIM number 607461). Pathogenic variants in the gene have been reported to cause Dyggve-Melchior-Clausen (DMC; OMIM 223800) dysplasia and Smith-McCort (SMC; OMIM 607326) dysplasia. (2) Methods: In the present study, large consanguineous families with five affected individuals with osteochondrodysplasia phenotypes were recruited. The family members were analyzed by polymerase chain reaction for homozygosity mapping using highly polymorphic microsatellite markers. Subsequent to linkage analysis, the coding exons and exon intron border of the DYM gene were amplified. The amplified products were then sent for Sanger sequencing. The structural effect of the pathogenic variant was analyzed by different bioinformatics tools. (3) Results: Homozygosity mapping revealed a 9 Mb homozygous region on chromosome 18q21.1 harboring DYM shared by all available affected individuals. Sanger sequencing of the coding exons and exon intron borders of the DYM gene revealed a novel homozygous nonsense variant [DYM (NM_017653.6):c.1205T>A, p.(Leu402Ter)] in affected individuals. All the available unaffected individuals were either heterozygous or wild type for the identified variant. The identified mutation results in loss of protein stability and weekend interactions with other proteins making them pathogenic (4) Conclusions: This is the second nonsense mutation reported in a Pakistani population causing DMC. The study presented would be helpful in prenatal screening, genetic counseling, and carrier testing of other members in the Pakistani community.

Citation

Abu Bakar, Sulaiman Shams, Nousheen Bibi, Asmat Ullah, Wasim Ahmad, Musharraf Jelani, Osama Yousef Muthaffar, Angham Abdulrhman Abdulkareem, Turki S Abujamel, Absarul Haque, Muhammad Imran Naseer, Bushra Khan. A Novel Homozygous Nonsense Variant in the DYM Underlies Dyggve-Melchior-Clausen Syndrome in Large Consanguineous Family. Genes. 2023 Feb 17;14(2)