Affordable Access

Different phenotypes of Friedreich's ataxia within one 'pseudo-dominant' genealogy: relationships between trinucleotide (GAA) repeat lengths and clinical features.

Authors
  • Illarioshkin, S N
  • Bagieva, G K
  • Klyushnikov, S A
  • Ovchinnikov, I V
  • Markova, E D
  • Ivanova-Smolenskaya, I A
Type
Published Article
Journal
European journal of neurology
Publication Date
Sep 01, 2000
Volume
7
Issue
5
Pages
535–540
Identifiers
PMID: 11054139
Source
Medline
License
Unknown

Abstract

We examined a large Turkmen family with 'pseudo-dominant' inheritance of Friedreich's ataxia resulting from consanguineous marriage of a Friedreich's ataxia patient to a heterozygote carrying an ancestral mutated allele. Two distinct phenotypes of the disease co-segregated within this genealogy. Two brothers from the younger generation exhibited 'classical' Friedreich's ataxia with onset of symptoms before 10 years and a rapidly progressive course. In contrast, three patients (two sisters from the younger generation and their father) had a more benign phenotype of late-onset Friedreich's ataxia with the onset at 26, 45 and 48 years and slow progression over decades. The patients with 'classical' Friedreich's ataxia were homozygous for a common ancestral expanded allele of the X25 gene containing 700-800 GAA repeats, while the patients with late-onset Friedreich's ataxia had two different mutated alleles, the shorter 250-repeat expansion of paternal origin and the longer 700-repeat expansion of maternal origin. One may conclude that clinical variability of Friedreich's ataxia in our patients is accounted for predominantly by a modifying effect of one of the two (shorter or longer) expanded alleles inherited from their affected father. Our observation clearly demonstrates the significance of variable-sized alleles for the phenotypic expression of the disease.

Report this publication

Statistics

Seen <100 times