Polydactyly in 22q11 syndrome: should it be taken into account?

Generalized skeletal dysplasia in mother and daughter with 22q11 deletion syndrome

“…Since individuals with 22q11 deletion syndrome have a predisposition toward autoimmune disorders including juvenile rheumatoid arthritis [Verloes et al, 1998], idiopathic thrombocytopenic purpura [Lévy et al, 1997], and Graves disease [Kawame et al, 2001], autoimmune thyroiditis in the girl and mother may be a syndromic constituent of 22q11 deletion syndrome, although it remains uncertain whether this is based on T cell dysfunction as in other autoimmune disorders. Individuals with 22q11 deletion syndrome show a variety of skeletal malformations, such as radial aplasia [Digilio et al, 1997], polydactyly [Sánchez‐Ramón et al, 2000], supernumerary ribs, “butterfly” vertebral body [Ming et al, 1997], and the Kenny‐Caffey syndrome phenotype [Sabry et al, 1998]. It has been suggested that these malformations result from haploinsufficiency of the TBX1 gene that is assigned to the region commonly deleted in 22q11 deletion syndrome, because the murine orthologous gene Tbx1 is expressed in the vertebral column [Chapman et al, 1996], and its haploinsufficiency causes aortic arch defects [Lindsay et al, 2001].…”