Brachydactyly with Novel BMP8A and FGFR1 Variants: A Case Report with Review of Literature.

Bone morphogenetic proteins (BMPs) and the fibroblast growth factor receptor 1 (FGFR1) gene play essential roles in the development and maintenance of the skeletal system. Brachydactyly is a genetic condition characterized by shortened or missing bones in the hands and feet. Several types of brachydactyly have been identified, each associated with different genetic mutations. However, some cases do not fit into existing classifications, necessitating further genetic investigation. A 34-year-old female patient with an absent middle phalanx in the second digit of her left foot and her 13-year-old son, who presented with absent or malformed middle and distal phalanx in all ten toes, are evaluated. Whole Genome Sequencing (WGS) analysis identifies a missense variant (c.1073A >T; p.K358M) in the BMP8A gene and a novel missense variant (c.1787C >T, p.Ser596Phe) in the FGFR1 gene. Functional protein association network analysis demonstrates a strong association of BMP8A and FGFR1 with other brachydactyly disease-causing genes. Given that these mutations have not been previously linked to any recognized brachydactyly subtype, they likely define a distinct genetic condition. The findings suggest a novel form of brachydactyly, which naming is proposed as brachydactyly type AB.