To the Editor With great interest we read the article by Renaud et al1 reporting a case series of 9 patients with autosomal recessive cerebellar ataxia type 3 due to ANO10 mutations. The authors discussed the previously reported c.132dupA mutation with a heterozygote carrier frequency of 1/184 and postulated that the homozygote state of this mutation would either have a more severe phenotype or not be viable at all.