Two coding single nucleotide polymorphisms in the SALL1 gene in Townes-Brocks syndrome: a case report and review of the literature.

Townes-Brocks syndrome (TBS) is an autosomal dominantly inherited malformation syndrome characterized by imperforate anus and limb and ear malformations with sensorineural hearing loss. Mutations in SALL1, a gene mapping to chromosome 16q21.1, are responsible for TBS. Here, we described a 16-month-old male patient with typical TBS clinical features including imperforate anus and preaxial polydactyly. Two coding polymorphism sites were identified in this case. One is silent (rs1965024, 2574 C > T), whereas the other yields a new codon encoding a different amino acid (rs4614723, 3823 G > A). The hot spot mutations in exon 2 were not suggested. Therefore, lack of SALL1 gene mutations and the presence of variable phenotypes in the sporadic cases might suggest DNA alternations in the noncoding regions of SALL1 gene and/or in other genes modulating SALL1 gene expression or functions.