Congenital myotonic dystrophy associated with a chromosome pericentric inversion.

We report two cases of congenital myotonic dystrophy (CMyD) associated with a chromosome abnormality of pericentric inversion. Case 1 was a two-month-old boy, presented with 46 XY, inv (9) (p 11q 13). His father had the same chromosome abnormality without any clinical manifestations. His mother had clinical manifestations of myotonic dystrophy (MyD) but had no chromosomal aberration. Case 2 is a one-month-old girl, presented with 46 XX, inv (4) (p15.31q25). Her mother had clinical manifestations of MyD and the same chromosome abnormality as Case 2, but her father was normal. Our case report may be of value in adding further information on the pathogenesis of CMyD.