Townes-Brocks Syndrome (TBS): Types 1 and 2

In 1972, Townes and Brocks published a report of the disease in a father and 5/7 of his children, suggesting an autosomal dominant transmission (Townes and Brocks 1972). They had imperforate anus with hand, foot, and ear defects. This syndrome is mainly characterized by the triad of imperforate anus, dysplastic ears, and thumb malformations (Kohlhase 1993). There is a wide variation in the presentation among the affected individuals, but other common features include sensorineural and/or conductive hearing loss, renal malformations, congenital heart disease, foot malformations, as well as intellectual disability. The exact prevalence of this syndrome is still unclear as the clinical distinction is challenging due to overlap with similar syndromes. The minimal frequency is estimated as 0.42 cases per 100,000 live-born infants (Martinez-Frias et al. 1999). Webb et al. reported DACT1 gene variant in a family who shared TBS-like phenotypes except for thumb abnormalities (TBS2) (Webb et al. 2017).