[Congenital type I fiber hypotrophy myopathy (author's transl)].

Five cases with type I fiber hypotrophy myopathy from two families are reported. The first two cases belong to the type I fiber hypotrophy and central nuclei. Six cases have already been published. In addition to hypotonia, obvious thoracic anomalies are associated. The three other cases are members of the second sibship and belong to the type I fiber hypotrophy without central nuclei nor myothony and show the typical phenotypic characters: elongated face and adynamic appearance. Out of these three brothers, two show no progress and the other is getting worse slowly. The pathological findings together with the evolutive-clinic pattern of these patient are confronted with those published by other authors and sugestions are made to differentiate these two forms and to establish their relationships with the other types of congenital myopathies, mainly with centronuclear myopathy and congenital fiber type disproportion.