DNA Marker Studies Show That Machado Joseph Disease is Not an Allele of The Huntingdon Disease Locus

Machado Joseph Disease (MJD) is a progressive spinocerebellar atrophy (SCA) with an autosomal dominant mode of inheritance. On the basis of some similarities in the clinical features and in the abnormal profiles of brain proteins, it has been suggested that MJD might be an allele of the Huntington Disease (HD) locus. Using the DNA probe (pK082), we analyzed the linkage between the DNA marker locus D4S10 and the MJD locus in two large kindreds. The data exclude linkage between these two loci at a distance of 10 cm (Z = - 2.02). Since the D4S10 locus is linked to the HD locus at a distance of approximately 4 cm, we conclude that MJD is not an allele of the HD locus.