[Adult metachromatic leucodystrophy (author's transl)].

A new adult case of metachromatic leucodystrophy (MLD) is reported. The earliest clinical signs are psychiatric in contra-distinction with the prevalent neurological signs observed in infantile or juvenile MLD. Although the occurrence of psychiatric features in adolescents or adults does not at first suggest MLD, it is easy to ascertain the diagnosis by combining the enzymatic assay of arylsulfatase A on leucocytes or cultured fibroblasts with the morphological study of nerve bundles. Such a discovery has of course a major importance in genetic counselling.