Hereditary Myopathy With Early Respiratory Failure: A Case Report and Review of the Literature

INTRODUCTION: Hereditary myopathy with early respiratory failure (HMERF) is a rare myopathy resulting from a mutation on the TTN region of the titin gene. A case report and a thorough review of PubMed-reported cases were conducted. DESIGN/METHODS: A 53-year-old man reported progressive lower extremity weakness and dyspnea. On examination, he had steppage gait and muscle strength was reduced in lower limb muscles. Electromyography showed myopathic findings in iliopsoas and gastrocnemius muscles. A lumbar magnetic resonance imaging demonstrated patchy fatty atrophy of iliopsoas and lumbar paraspinals muscles. Next-generation sequencing revealed a heterozygous titin gene (TTN) mutation c.95187 G > C (p.Trp31729Cys) consistent with the diagnosis of HMERF. RESULTS: Fifty-eight patients of HMERF (14-78 years old) were identified. The earlier age of onset was 14 years. Most patients presented with limb muscle weakness but 11 began with an initial respiratory complaint. On average, patients required noninvasive ventilation 5.5 years postsymptom onset. CONCLUSIONS: HMERF should be considered in the differential diagnosis of an adult with concomitant respiratory and limb muscle weakness.