PRESYMPTOMATIC TESTING FOR AUTOSOMAL-DOMINANT SPINOCEREBELLAR ATAXIA TYPE-1

Presymptomatic testing was done on four people from a large family in which an autosomal dominant form of spinocerebellar ataxia was segrega ting. Earlier genetic analysis had shown that in this family the disor der was tightly linked to an informative microsatellite polymorphism o n chromosome 6p. Two subjects with prior risks of 50% of developing th e disease had final risks after testing of 2%; the other two with prio r risks of 25% had final risks of 1%. Chromosome 6p linked spinocerebe llar ataxia may now be added to Huntington's disease as a late onset d isorder in which genetic linkage may be used to carry out presymptomat ic testing.