Infantile fibre type disproportion, myofibrillar lysis and cardiomyopathy: a disorder in three unrelated Dutch families.

An apparently new cardioskeletal myopathy is reported in three unrelated families. Five infants were affected by rapidly progressive generalized muscle weakness, with onset shortly after birth, and dilated cardiomyopathy. All had generalized tremor (clonus) starting in the first week of life.