Duplication of 7q36.3 encompassing the Sonic Hedgehog (SHH) gene is associated with congenital muscular hypertrophy

Muscular hypertrophy is a very rare finding on foetal ultrasonography. We present a case with recurrent muscular hypertrophy, liver enlargement and polyhydramnios in two pregnancies. One pregnancy was terminated due to suspicion of a storage disease, whereas the other led to delivery of a boy with muscular hypertrophy and mildly retarded psychomotor development. Array-CGH identified a small duplication of 7q36.3 including the Sonic Hedgehog (SHH) gene in both the aborted foetus and the live born male sib. Neither of the parents carried the 7q36.3 duplication. The consequences of overexpression of SHH in humans are not elucidated, but animal studies have suggested its importance in muscular hypertrophy. We suggest that the clinical findings in the presented case might be explained by the duplication and presumed overexpression of SHH.

► We report two siblings with a dup 7q36.3 encompassing the Sonic Hedgehog (SHH) gene.
► Both children had congenital muscular hypertrophy.
► We suspect gonadal mosaicism, since the parents did not carry the duplication.
► We suggest that the muscular hypertrophy is explained by overexpression of SHH.