Accuracy of clinical diagnostic criteria for Friedreich's ataxia

The accuracy of the diagnostic criteria for Friedreich's ataxia proposed by Harding and by the Quebec Cooperative Study on Friedreich's Ataxia was stu died in 142 patients with progressive unremitting ataxia of autosomal reces sive inheritance or sporadic occurrence. Eighty-eight patients received the molecular diagnosis of Friedreich's ataxia. Traditional diagnostic criteri a are characterized by high specificity, but they yield a high number of fa lse-negative diagnoses. We suggest three levels of diagnostic certainty: (1 ) possible Friedreich's ataxia, defined as sporadic or recessive progressiv e ataxia with (a) lower limb areflexia and dysarthria, Babinski sign, or el ectrocardiographic repolarization abnormalities, or Cb) with lower limb ret ained reflexes and electrocardiographic repolarization abnormalities (95% s ensitivity and 88% positive predictive value); (2) probable Friedreich's at axia as defined by Harding's criteria (63% sensitivity and 96% positive pre dictive value) or by Quebec Cooperative Study on Friedreich's Ataxia criter ia (63% sensitivity and 98% positive predictive value); (3) definite diagno sis, molecularly confirmed.