CTG triplet repeat expansion in a laryngeal carcinoma from a patient with myotonic dystrophy

A 66-year-old Japanese man with myotonic dystrophy (DM) underwent total laryngectomy for laryngeal carcinoma. The size of the expanded DNA fragment (EF) from the leukocytes and normal laryngeal tissues of this patient was only slightly longer than that in normal subjects. EF, however, was markedly longer in the laryngeal carcinoma. These findings support the hypothesis that elongation of the CTG repeat in the DM kinase gene occurs during acquired cell proliferation.