Test Details: Myotonic dystrophy type 1 (DM1) is a multisystem disorder that affects skeletal and smooth muscle as well as the eye, heart, endocrine system, and central nervous system. It is an autosomal dominant hereditary disorder caused by expansion of a CTG trinucleotide repeat in the noncoding region of gene DMPK.   The test is done in first trimester of the fetal sample to identify the risk factor for the disease.