Myotonic dystrophy is the most common form of adult onset muscular dystrophy and has an incidence of 1/8000 individuals. The genetic defect in the disorder is the expansion of a (CTG) trinucleotide repeat in the DMPK gene. This autosomal dominant disorder is characterized by myotonia, muscle wasting, frontal balding, hypogonadism, and ocular and ECG abnormalities. Genetic anticipation is commonly seen in families with myotonic dystrophy. In these families, extreme amplification can occur during mother to child transmission of the abnormal allele leading to a congenital form of the disease. Congenital myotonic dystrophy can be associated with a very severe disease state including generalized hypotonia and intellectual disability. Molecular diagnosis of myotonic dystrophy involves a combination of Southern blotting tests and direct PCR analysis to determine the (CTG) repeat number.