Autosomal dominant spinocerebellar ataxias ad infinitum?

The inherited ataxias have always been a clinician’s nightmare. Molecular geneticists have documented the genetic heterogeneity of progressive autosomal dominant ataxias, which are now labeled “spinocerebellar ataxia” (SCA) and are followed by a number assigned for each new gene locus. In this issue of Neurology , O’Hearn et al.1 address the phenotype associated with the SCA 12 mutation first described in December 1999,2 and Worth and Wood3 document the rarity of this mutation among patients at a referral institution in the UK. The dizzying pace of gene discovery is such that the list has already grown to 16 ( table 1). The table does not include the dominantly inherited episodic ataxias (EA) related to point mutations in channel proteins; EA 2, …