Our findings reveal that this family had a congenital to adult-onset mildly progressive myopathy with hanging big toe, spine and hand contractures, and cardiomyopathy and no features of nemaline or cap myopathy, but with specific ultrastructural changes consisting in disruption of the regular square pattern of the Z line, extending the clinical heterogeneity of recessive MYPN mutations. The gene discussed is MYPN; the disease is cardiomyopathy.