The patient, previously diagnosed with anti-3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) antibody-associated myopathy, exhibited progressive weakness and dysphagia, prompting suspicion of PNM. The patient's compromised respiratory status, attributed to tracheal compression by a large goiter, necessitated an urgent thyroidectomy. The gene discussed is HMGCR; the disease is myopathy.