Whole exome sequencing identifies FGF16 nonsense mutations as the cause of X-linked recessive metacarpal 4/5 fusion

Background: Metacarpal 4-5 fusion (MF4; MIM %309630) is a rare congenital malformation of the hand characterised by the partial or complete fusion of the fourth and fifth metacarpals. The anomaly occurs as an isolated trait or part of a genetic syndrome.

Methods: To search for disease-causing mutation, whole exome sequencing (WES) was performed on samples from a single trio. Before WES, molecular screening including gene sequencing and array comparative genomic hybridisation was applied. Validation of WES and segregation studies were done using routine Sanger sequencing.

Results: Exome sequencing detected a nonsense mutation (c.C535T; p.R179X) in exon 3 of the FGF16 gene, which maps to chromosome Xq21.1. Mutational screening of the FGF16 gene performed in an unrelated proband of different ethnicity showed another nonsense mutation in exon 3 (c.C470A; p.S157X).

Conclusions: This study shows that truncating mutations of FGF16 are associated with X-linked recessive metacarpal 4-5 fusion. The study provides evidence for the involvement of FGF16 in the fine tuning of the human skeleton of the hand.

FGF16; X-linked inheritance; metacarpal 4-5 fusion; metacarpal synostosis; nonsense mutation.