DMPK and myotonic dystrophy: Most intriguingly, people with myotonic dystrophy, which is caused by autosomal dominant repeat expansions disrupting the first exons of the muscle genes DMPK (in type 1) or CNBP (in type 2), develop a significantly elevated number of thyroid, endometrium, ovary, melanoma, colon/rectum, and testis cancers (59).