SAT-510 Association of Myotonic Dystrophy with Autoimmune Endocrinopathies and Thyroid Carcinoma

Abstract

Myotonic dystrophy (MD) is a multisystemic, autosomal dominant disorder associated with progressive muscle weakness, premature cataracts, frontal baldness, and cardiac disturbances. MD has been associated with several endocrinopathies including primary testicular failure, autoimmune endocrinopathies (hypothyroidism, hyperthyroidism, multinodular goiter, and Addison’s disease), thyroid carcinoma (primarily papillary), insulin resistance, and type 2 DM. Development of diabetes is thought to be related to formation of an insulin-resistant receptor because of aberrant regulation of mRNA. We describe the first reported case of a patient with MD associated with type I diabetes mellitus, Hashimoto’s thyroiditis with hypothyroidism, and follicular variant of papillary thyroid cancer. A 49-year-old female presented with acute congestive heart failure. The patient had history of type I DM diagnosed at the age of 26, complicated by mild background retinopathy, peripheral neuropathy, and nephropathy with microalbuminuria. The patient first noticed proximal muscle weakness 1 year ago that gradually progressed resulting in multiple falls. She had history of bilateral cataracts status post cataract extraction at age 26. She also had progressive dysphagia requiring PEG placement, and cognitive dysfunction with mood disorder and depression. Family history was significant for myotonic dystrophy in both maternal aunt and uncle as well as 2 cousins. EMG confirmed myotonia however genetic testing was not obtained due to cost. Due to her cognitive dysfunction and depression, she had difficult to control diabetes with HbA1c of 9.9%, and multiple previous admissions for DKA. She was status post total thyroidectomy in 2008 for follicular variant of papillary carcinoma and Hashimoto’s thyroiditis followed by I-131 therapy in 2009 and maintained on levothyroxine suppression therapy. Most recent Tg and Tg Ab were undetectable. On physical exam, the patient had a narrow, sallow face with temporal muscle atrophy, percussion myoclonus involving the thenar eminence of the hands, but no frontal balding. Work up showed LVEF of 20-24% with regional hypokinesis that led to catherization and PCI to LAD. The patient had recurrent NSTEMI which eventually resulted in CABG 1 year after presentation. The association of autoimmune endocrinopathies, thyroid carcinoma and MD suggests a possible cause and effect relationship between these disorders. In patients with diabetes and MD, previously described insulin resistance as well as cognitive dysfunction can hinder good glycemic control increasing risk for complications. Although patients with MD are typically treated by neurologists, evaluation and therapy of endocrine dysfunctions are also necessary.