Abstract Introduction Hereditary myopathy with early respiratory failure (HMERF) is a slowly progressive autosomal dominant gene mutation myopathy related to transthyretin (TTN). Symptoms typically begin in the third to fifth decades of life with distal muscle weakness and dyspnea on exertion. Patients typically need walking assistance and nocturnal PPV within 5-10 years of diagnosis. Here, we present a case of HMERF with isolated respiratory symptoms delaying diagnosis due to an atypical presentation Case Presentation A 55-year-old man with no smoking history, obesity, severe obstructive sleep apnea, presented to primary care clinic with worsening dyspnea on exertion. This dyspnea was initially worked up for cardiac etiology TTE demonstrated a normal ejection fraction with mild mitral regurgitation and diastolic dysfunction (grade I) A pulmonary function test showed moderate restriction, normal diffusion suggestive of an extrathoracic restriction. HRCT showed no interstitial disease. Neuromuscular specialists were consulted and completed diaphragm EMG, muscle biopsy and genetic testing consistent with HMERF with TTN associated gene mutation. The patient was placed on nocturnal BiPAP with improvement in symptoms. Discussion Only 5% of HMERF cases are due to a TTN gene mutation. Typical presentation starts with distal leg weakness and foot drop alongside dyspnea with exertion. Muscle weakness was absent in this case. In patients with an otherwise normal PMH that present with isolated dyspnea on exertion, myopathic etiologies must remain high on the differential when there is a lack of other concerning symptoms. Conclusion In summary, early neuromuscular evaluation and genetic testing are critical in patients with unexplained dyspnea on exertion to avoid delayed diagnosis and optimize management of HMERF. This abstract is funded by: none
Gibson et al. (Fri,) studied this question.