Any hypertrophic cardiomyopathy in which the cause of the disease is a mutation in the NEXN gene. The disease is MONDO_0013477 (hypertrophic cardiomyopathy 20). Also known as: CMH20, NEXN hypertrophic cardiomyopathy, cardiomyopathy familial hypertrophic 20, cardiomyopathy, familial hypertrophic, type 20, cardiomyopathy, hypertrophic, 20, hypertrophic cardiomyopathy caused by mutation in NEXN, hypertrophic cardiomyopathy type 20.