Three-point linkage analysis employing C3 and 19cen markers assigns the myotonic dystrophy gene to 19q.

In seven large families with myotonic dystrophy (DM) comprising 102 individuals, linkage studies were performed employing restriction fragment length polymorphisms in the complement component 3 gene and the 19cen C banding heteromorphism as genetic markers. Three-point linkage analysis excludes DM from the 19cen-C3 segment and strongly supports its assignment to the proximal long arm of chromosome 19.