A novel homozygous missense mutation in BHLHA9 causes mesoaxial synostotic syndactyly with phalangeal reduction in a Pakistani family.

Mesoaxial synostotic syndactyly with phalangeal reduction (MSSD) is a rare non-syndromic limb malformation with autosomal recessive inheritance. To date, only a few affected families with MSSD who had BHLHA9 mutations have been reported. The present report describes a consanguineous Pakistani family with five affected individuals with MSSD who exhibited an autosomal recessive pattern. Genotyping followed by Sanger sequencing was performed, and we identified a novel homozygous missense mutation (c.311T>C, p.Ile104Thr) in the BHLHA9 gene. This finding expands the spectrum of known mutations in the BHLHA9 gene that cause MSSD.