Introduction: Distal myopathies are currently regarded as a non-homogeneous group of disorders including different autosomal dominant, recessive and sporadic forms.
Material and methods: The cases of a mother and her son and daughter are described and compared to previously reported cases from 4 families. Despite minor differences, the clinical picture is remarkably homogeneous, both within the same family and among different families.
Conclusion: A distinct clinical form can be identified including: a) autosomal dominant inheritance; b) onset in infancy or childhood with peroneal muscles weakness; c) not disabling evolution in spite of possible late involvement of muscles others than tibio-peroneal; d) usually normal serum CK and other muscle enzymes; e) EMG evidence of primary myogenic damage; f) morphological findings of non-specific myopathy. Because of the benign evolution and the absence of true dystrophic changes in most biopsies we suggest the term infantile autosomal dominant distal myopathy should be preferred to infantile autosomal dominant distal muscular dystrophy.