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

Purpose: 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. Methods: We performed a retrospective analysis of eight patients with HFM-expanded spectrum and anal anomalies to determine whether this subset has TBS. Results: 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." Conclusion: Patients with overlapping features of both syndromes should be screened for SALL1 mutations.