Machado-Joseph disease in east Arnhem Land, Australia: chromosome 14q32.1 expanded repeat confirmed in four families.

Four kindreds of east Arnhem Land Australian aboriginal people from Groote Eylandt and adjacent communities display symptoms of a similar spinocerebellar degeneration (multiple-system degenerative disease). The familial pattern indicates an autosomal dominant inheritance, though with varying penetrance in different families. This condition is clinically and pathologically consistent with Machado-Joseph disease (MJD), and there is the possibility of Portuguese ancestry. These families exhibit anticipation, particularly in the case of paternal inheritance, with those with earlier age of onset presenting a clinical pattern consistent with MJD type I. There was no expansion of the CAG repeat region of the SCA1 gene in these families. The demonstration of expansion of the CAG repeat on chromosome 14q32.1 in all four families confirms the diagnosis of MJD.