title: Trinucleotide (GAA)n repeat expansion in two families with Friedreich's ataxia with retained reflexes.
abstract: In occasional families in whom cases of classic Friedreich's ataxia (FRDA) coexist with affected cases with retained reflexes, linkage analysis has shown that both map to the FRDA locus on chromosome 9q13-21.1. A gene X25 has been identified within the critical region of the FRDA locus, and an intronic expanded GAA trinucleotide repeat has been found in most cases of FRDA. We report two further FRDA families in whom some patients with classic FRDA were areflexic whereas others had brisk reflexes. Molecular genetic analysis disclosed an abnormal trinucleotide repeat expansion within intron 1 of the FRDA gene in both phenotypes.
authors.affiliation: The Walton Centre for Neurology and Neurosurgery, Liverpool, UK.
authors.forename: M W
authors.initials: MW
authors.lastname: Kellett
authors.forename: N A
authors.initials: NA
authors.lastname: Fletcher
authors.forename: N
authors.initials: N
authors.lastname: Wood
authors.forename: T P
authors.initials: TP
authors.lastname: Enevoldson
mesh_terms: D000293:Adolescent; D000328:Adult; D000483:Alleles; D002869:Chromosome Aberrations; D025063:Chromosome Disorders; D002899:Chromosomes, Human, Pair 9 / Q000235:genetics; D005260:Female; D005621:Friedreich Ataxia / Q000235:genetics*; D005796:Genes / Q000235:genetics; D006801:Humans; D010641:Phenotype; D017354:Point Mutation / Q000235:genetics; D018911:Trinucleotide Repeats / Q000235:genetics*