A novel homozygous FAM92A gene (CIBAR1) variant further confirms its association with non‐syndromic postaxial polydactyly type A9 (PAPA9)

• Published in: Clinical genetics 2024-10, Vol.106 (4), p.488-493
• Main Authors: Umair, Muhammad, Ahmed, Zaheer, Shaker, Bilal, Bilal, Muhammad, Al Abdulrahman, Abdulkareem, Khan, Hammal, Jawad Khan, Muhammad, Alfadhel, Majid
• Format: Article
• Language: English
• Subjects: FAM92A gene; molecular docking; Mutation; novel variant; PAPA9; Pattern formation; Phenotypes; Polydactyly; Protein structure; Proteins; Secondary structure; WES; Whole genome sequencing
• ISSN: 0009-9163; 1399-0004; 1399-0004
• DOI: 10.1111/cge.14572

Polydactyly is a very common digit anomaly, having extra digits in hands and/or toes. Non‐syndromic polydactyly in both autosomal dominant and autosomal recessive forms are caused by disease‐causing variants in several genes, including GLI1, GLI3, ZNF141, FAM92A, IQCE, KIAA0825, MIPOL1, STKLD1, PITX1, and DACH1. Whole exome sequencing (WES) followed by bi‐directional Sanger sequencing was performed for the single affected individual (II‐1) of the family to reveal the disease causative variant/gene. 3D protein modeling and structural molecular docking was performed to determine the effect of the identified mutation on the overall protein structure. WES revealed a novel biallelic missense variant (c.472G>C; p.Ala158Pro) in exon 6 of the FAM92A gene. The identified variant segregated perfectly with the disease phenotype using Sanger sequencing. Furthermore, Insilco analysis revealed that the variant significantly changes the protein secondary structure, and substantially impact the stability of FAM92A. We report the second FAM92A disease‐causing mutation associated with recessive non‐syndromic postaxial polydactyly. The data further confirms the contribution of FAM92A in limb development and patterning. Schematic representation of the workflow followed in the present study. Stating from patient recruitment, exome sequencing, variant filtration, and Sanger sequencing. To see the pathogenic nature of the variant 3D protein modeling was performed.