Characterization of the Interruptions of the GAA Expansion and Study of Their Influence on the Severity of Friedreich's Ataxia

• Conditions: Friedreich Ataxia
• Interventions: Other: Reuse of existing data from patients' medical records

• Registration Number: NCT04346238
• Lead Sponsor: University Hospital, Montpellier

Brief Summary

Friedreich's ataxia (FA) is the most frequent recessive genetic ataxia with an estimated prevalence of 1/50 000. The first symptoms appear around the age of 10 years with a progressive course and the need for an armchair 10- 15 years after the first symptoms. More rarely the disease can present with a late onset (after the age of 25) with a picture characterized by spastic paraparesis and slower progression ("LOFA" for "Late Onset Friedreich Ataxia" or VLOFA for "Very Late Appearance of Friedreich's ataxia ").

AF is caused in 96% of cases by an expansion of GAAN triplets (N\> 100 repeats) located in intron 1 of the FXN gene, present on the two alleles, and, in the rest of the cases, by an associated expansion a point mutation or a deletion in trans. During molecular diagnostics, it is not uncommon to find the presence of interruptions within the GAA expansion. This results in the absence and / or the shift of peak (s) within the chromatogram.

To date, only the partial correlation between the size of the expansion and the age of onset of Friedreich's ataxia has been established. In particular, very atypical forms of AF with a late onset (after the age of 25) are in particular explained by the low number of repetitions in the expansion, typically between 100 and 500 repetitions. However, the presence of an interruption could stabilize the size of the expansion and, therefore, be mainly associated with expansions of small sizes and therefore with a late onset of the disease.

The objective of this study is therefore to analyse and caracterize the presence and the type of interruptions of the GAA expansions in a group of patients with FA ; this data will be correlated with the age at onset of FA.

Detailed Description

Not available

Study Timeline

• Study Start: 2020-03-01
• Status Verified: 2020-04
• Study First Submitted: 2020-04-10
• Study First Submitted QC: 2020-04-10
• Study First Posted: 2020-04-15
• Last Update Submitted: 2020-04-15
• Last Update Posted: 2020-04-16
• Primary Completion: 2021-03-30
• Study Completion: 2021-09-30

Recruitment & Eligibility

• Status: UNKNOWN
• Sex: All
• Target Recruitment: 120

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
Patients with Friedriech Ataxia genetically confirmed	Reuse of existing data from patients' medical records	Patients with Friedriech Ataxia genetically confirmed

Primary Outcome Measures

Name	Time	Method
Interruptions and date at onset	18 months	Study the correlation between the presence and type of interruptions (location within the expansion, nucleotide sequence: "GAAA", "GAG", etc.) and the age of onset of Friedreich's ataxia.

Secondary Outcome Measures

Name	Time	Method
Clinical correlation	18 months	Estimate the interaction between the presence and type of interruption and the age of onset of the various functional impacts (walking, cardiac involvement).

Trial Locations

Locations (1)

Uh Montpellier; 🇫🇷 Montpellier, France