Relative frequencies of CAG expansions in spinocerebellar ataxia and dentatorubropallidoluysian atrophy in 116 Italian families

Two hundred and forty-eight patients from 116 Italian families with dominan t ataxia were studied for CAG expansion within SCA1, 2, 3, 6, 7 (spinocereb ellar ataxia) and DRPLA (dentatorubropallidoluysian atrophy) genes. Fifty-s ix percent of the families originated from Southern, 19% from Central and 2 5% from Northern Italy. SCA2 was the commonest mutation, accounting for 47% of the families, followed by SCA1 (24%), SCA6 (2%), SCA7 (2%) and DRPLA (1 %). No SCA3 family was found. Twenty-four percent of the families carried a still unidentified mutation. When occurrence of mutations was evaluated ac cording to the geographic origin, SCA1 was the commonest in Northern (72%), whereas SCA2 was prevalent (63%) in Southern Italy. The number of CAG repe ats in SCA1 normal alleles was higher in Northern than in Central-Southern Italy. Copyright (C) 2000 S. Karger AG, Basel.