Hereditary myopathy with early respiratory failure

Neuromuscular diseases can present with acute respiratory failure with no other symptoms. A 30-year-old woman presented with progressive dyspnoea, culminating in respiratory failure requiring critical care admission for non-invasive ventilation. On examination, she had proximal and distal muscle weakness with bilateral scapular winging. An MR scan of the muscle showed selective fatty replacement in the semitendinosus, tibialis anterior and peroneus longus muscles. Muscle biopsy identified rimmed vacuoles, core-like structures and desmin-positive aggregates. Genetic testing identified a novel heterozygous missense mutation (c.95350G>A, p.Ala31784Thr) in the fibronectin type-III 119 domain of the TTN gene, leading to the diagnosis of hereditary myopathy with early respiratory failure (HMERF). Her muscle weakness has since progressed over 3 years, and she still depends on non-invasive ventilation. Clinicians should consider HMERF in adults presenting with unexplained respiratory failure.