A new mutation in the TBX5 gene in Holt-Oram syndrome: two cases in the same family and prenatal diagnosis.

Holt-Oram Syndrome (HOS) is a rare autosomal dominant condition characterized by anomalies of the upper extremity and cardiac malformations. Mutations in the TBX5 gene are what cause HOS. The proband is an 8-year-old male who presented with upper-extremity abnormalities and a chest deformity. He was born to a nonconsanguineous marriage at full term. He has a history of ventricular septal defect. His mother presented with deformation in both hands and forearms, and was 9 weeks' pregnant. Mutation analysis for TBX5 gene revealed heterozygous p.L65Qfs*10 in both the patient and his mother. Molecular analysis of the fetus was normal for TBX5 gene in the 13th week of pregnancy. In conclusion, our case supports the fact that the HOS presents differently, case by case, even within the same family. The novel mutation reported here and phenotypic findings in the affected members may contribute to the phenotype-genotype correlation.