Heterozygous Pathogenic Variant in DACT1 Causes an Autosomal-Dominant Syndrome with Features Overlapping Townes-Brocks Syndrome
- Hum Mutat. 2017 Apr;38(4):373-377. doi: 10.1002/humu.23171.
- 1. Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York.
- 2. Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York.
- 3. Icahn Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, New York.
- 4. Bell Center for Regenerative Biology and Tissue Engineering and National Xenopus Resource, Marine Biological Laboratory, Woods Hole, Massachusetts.
- 5. Department of Pediatrics, Division of Genetics, Nemours Children's Clinic, Orlando, Florida.
A heterozygous nonsense variant was identified in dapper, antagonist of beta-catenin, 1 (DACT1) via whole-exome Sequencing in family members with imperforate anus, structural renal abnormalities, genitourinary anomalies, and/or ear anomalies. The DACT1 c.1256G>A;p.Trp419* variant segregated appropriately in the family consistent with an autosomal dominant mode of inheritance. DACT1 is a member of the Wnt-signaling pathway, and mice homozygous for null alleles display multiple congenital anomalies including absent anus with blind-ending colon and genitourinary malformations. To investigate the DACT1 c.1256G>A variant, HEK293 cells were transfected with mutant DACT1 cDNA plasmid, and immunoblotting revealed stability of the DACT1 p.Trp419* protein. Overexpression of DACT1 c.1256G>A mRNA in Xenopus embryos revealed a specific gastrointestinal phenotype of enlargement of the proctodeum. Together, these findings suggest that the DACT1 c.1256G>A nonsense variant is causative of a specific genetic syndrome with features overlapping Townes-Brocks syndrome.