Townes-Brocks syndrome versus expanded spectrum hemifacial microsomia: review of eight patients and further evidence of a "hot spot" for mutation in the SALL1 gene.

Abstract

It can be difficult to differentiate clinically between hemifacial microsomia (HFM) and Townes-Brocks syndrome (TBS). The distinction is important because TBS is inherited as an autosomal dominant trait, whereas HFM is sporadic. We performed a retrospective analysis of eight patients with HFM-expanded spectrum and anal anomalies to determine whether this subset has TBS. Two patients had major phenotypic findings of TBS. Sequencing of SALL1, the gene mutated in TBS, in four of the eight patients revealed one with a C --> T transition (resulting in a nonsense mutation R276X) at a previously identified mutational "hot spot." Patients with overlapping features of both syndromes should be screened for SALL1 mutations.