Trisomy 13 is associated with anorectal malformations

Trisomy 13 with anorectal malformation: an association or an incidental finding?

This report describes a baby with trisomy 13 (Patau syndrome) with imperforate anus. It is very unusual for Patau syndrome to be associated with anorectal malformation. In the English medical literature, there are only four reported cases of trisomy13 being associated with imperforate anus: a partial trisomy of chromosome 13q and 20p [Nagai et al. Currarino triad (anorectal malformation, sacral bony abnormality and presacral mass) with partial trisomy of chromosomes 13q and 20p. Clin Genet. 1994;45:272–3.], a mosaic form [46,XX,t(13q13q)/46,XX,–13,+r(13)] (Jalal et al. Unusual mosaic trisomy 13 through 13/13 translocation and monosomy 13 with a small ring. Ann Genet. 1990;33:173–5.) of trisomy 13, a third case in which the form of trisomy 13 was not described (Cho et al. One hundred three consecutive patients with anorectal malformations and their associated anomalies. Arch Pediatr Adolesc Med. 2001;155:587–91.) and a fourth case of trisomy 13 with a Robertsonian translocation of the extra chromosome 13 to chromosome 14 (Lewis and Lander. Trisomy 13 is associated with anorectal malformations. Arch Dis Child. 2007;92:185.).

Genetics of Hirschsprung disease and anorectal malformations

Hirschsprung disease (HD) and anorectal malformations (ARMs) result from alterations in hindgut development. It has long been recognized that both recur in families and thus result, at least in part, from genetic factors. Progress in the understanding of the genetic basis of HD has been made by the application of findings from genetic animal models of altered enteric nervous system development to human beings. Several genes have been shown to be important for human enteric nervous system development, and current work is progressing to identify genetic interactions that may explain the variable phenotype of HD. By contrast, understanding of the genetic factors underlying ARMs is much less developed. We and others have shown that genetic factors play an important role in the pathogenesis of ARMs, and many mouse genetic models suggest molecular pathways that may be altered in ARMs.