High incidence of the R276X SALL1 mutation in sporadic but not familial Townes–Brocks syndrome and report of the first familial case

APA, anteriorly placed anus; APL, aplastic/aplasia; ASD, atrial septum defect; bil., bilateral; CFT, club feet; DPL, dysplastic; F, female; HPL, hypoplastic; HSP, hypospadias; IA, imperforate anus (type not specified); IUGR, intrauterine growth retardation; M, male; Micr., Microtia; MR, mental retardation; MMR, mild mental retardation; N, normal (clinically and by further testing if required); NR, no abnormality reported (clinically normal; no further testing performed); PC, polycystic; PP, preaxial polydactyly; RC, reduced clearance; RF, renal function; SNHL, sensorineural hearing loss; T, thumb; TT, triphalangeal thumbs; UG, urogenital; VSD, ventricular septum defect. Heart defects seem more common with the R276X mutation, and this is the only SALL1 mutation currently known to be associated with tetralogy of Fallot. [...]reduced genetic fitness might be another explanation for the rare familial occurrence of the R276X mutation.