A novel TBX5 missense mutation (V263M) in a family with atrial septal defects and postaxial hexodactyly.

Background: Congenital heart diseases are the most frequent birth defects and are commonly associated with skeletal malformations. Mutations in the TBX5 gene, a T-box transcription factor located on chromosome 12q24.1, have been demonstrated to be the underlying molecular alteration in individuals with different congenital cardiac disorders, notably the Holt-Oram syndrome.

Methods: Six members from a two-generation family from a consanguineous couple, which had atrial septal defects associated with postaxial hexodactyly in all extremities were clinically assessed and submitted to TBX5 mutational analysis performed by direct sequencing.

Results: We detected a new TBX5 missense mutation (V263M) in all four individuals studied with cardiac abnormalities. The genotype-phenotype correlations in light of unusual features are extensively discussed, as well as the possible significance of these atypical findings.

Conclusions: These new data extend our clinical and molecular knowledge of TBX5 gene mutations and also raise interesting questions about the phenotype heterogeneity regarding these gene alterations.