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A 5-year-old boy with occasional pain of brief duration at the right or the left leg during exercise since the age of 4 years is reported. There was no weakness nor any other abnormality at the neurological examination. The serum creatine phosphokinase activity was elevated three times out of four. The electromyogram showed myopathic abnormalities in the biceps, it was normal in quadriceps and anterior tibial muscles. A quadriceps muscle biopsy was performed. There were no histological nor histochemical abnormalities at the routine techniques. However, a completely negative reaction with myoadenylate deaminase ( MADA ) stain was found. The MADA enzymatic activity in the muscle was very low. It is likely that the clinical syndrome is related to MADA deficiency.

The analysis of 10 X-linked DNA polymorphisms (five mapping on the short arm and five on the long arm) in two Becker muscular dystrophy pedigrees has been used to localize this gene in the known sequence of DNA polymorphic markers on the X chromosome. In the first pedigree, the carrier mother, whose phase for Becker and for five informative polymorphisms is known, has transmitted a double recombinant X chromosome to one of her two affected sons. The discordance between these two affected brothers for four of the five informative polymorphisms indicates that the Becker gene is located between RC8 or D2 on one side and pDP34 on the other. In the second pedigree, where the maternal grandfather is dead and two maternal first cousins are affected, the phase of DNA polymorphic alleles has been identified in somatic cell hybrids resulting from the fusion of hamster fibroblasts with lymphocytes of the mothers and aunt of the patients. The discordance between the two first cousins for two of the four informative DNA polymorphisms is best explained by the occurrence of a single recombination in the X chromosome carried by one of them. This result further restricts the localization of the Becker gene to a region of the short arm delimited by B24 and L 1.28. Regional and fine gene mapping through the approach described in this paper should become useful in the future for X-linked as well as for autosomal genes.

Four cases of acute onset myelopathy in which clinical and instrumental findings led to the diagnosis of anterior spinal artery syndrome are reported. The physiopathology, clinical medicine and treatment of vascular myelopathies are discussed on the basis of the series presented and reported data. It is also pointed out that vascular aetiology underlies a certain number of acute myelopathies, otherwise classified indiscriminately as myelitis.

A 40 year-old woman with a rapidly progressive proximal muscle deficit of all four limbs had an acute myopathy secondary to hyperthyroidism. Biopsy of the quadriceps femoris revealed signs of non specific muscle impairment with type II fiber atrophy. Treatment with methimazole and correction of the thyroid condition led to rapid disappearance of the disorders. Eighteen months later the clinical status was normal and a second quadriceps femoris biopsy showed that the muscle had normalized.