Friedreich’s ataxia (FRDA) is an autosomal recessive spinocerebellar ataxia. In most cases, the disease is caused by homozygous, or compound heterozygote GAA triplet repeat expansion in the frataxin (FXN) gene. Shorter repeat expansion length correlates with age of onset and disease severity. The disease is manifested by showing a wide range of phenotypes. FRDA is a multisystem disease that affects both the central and peripheral nervous systems, the heart muscle, the musculoskeletal system, and the endocrine pancreas. Most FRDA cases are associated with a pathological expansion of the GAA repeats in the non-coding first intron of the FXN gene encoding Frataxin protein. The protein expression is suppressed due to the GAA expansion, causing pathological features ranging in phenotypes due to the size of the GAA expansion. The remaining cases (1–3%) are related to a compound heterozygous expansion with point mutations or deletions. Normal individuals have extended trinucleotide stretches of 40, and the pathological threshold is about 70. FRDA triplet numbers are most common in the 600-900 range, and like most autosomal disorders, the heterozygous carriers usually do not show any symptoms.
The GT FA Detector vC kit is designed to allow the expansion be either seen in agarose gel (for long repeats) or accurately sized on a CE system. When the expanded fragment is more than 1200 bp in length or around 175 repeats, CE usually can’t show the expanded allele but produces stutter peaks, which are indicative of the presence of expansion. Therefore, in normal individuals, we are expecting repeats of about 20 GAA. To assist repeat or allele calling or allele size expansion, we have incorporated bins in the panel. We have also designed a panel so that one can see roughly the severity of the disease based on repeat number and colors. The test can easily distinguish carriers from normal individuals based on the number of repeats and zygosity pattern. However, it is extremely important that the user of the kit uses the latest guidelines and best practices for the interpretation of results, particularly when the affected individual is not present in the family, to assist phenotype/genotype correlation. Even two individuals, having the same number of repeats, may manifest the symptoms with varying degrees due to gene/gene interactions or other modifying genes or other reasons. We can suggest reading the content on GeneReviews or you may consult with EMQN Best Practice Guideline.
GT FA Detector vC kit is simple to use, and the PCR product must be run on a CE systems like SeqStudio , 3130/xl or 3500/xL Genetic Analyzer from Thermo Fisher or Compact Spectrum CE System from Promega.
Premium Features
·For rapid and accurate detection of GAA repeat numbers in FXN gene;
·Easy to interpret results by having a special panel showing the repeat range.
·Allele calling is aided by incorporation of bins in the panel
·Easy to use, mix, and rapid PCR for results.
For research use only.
Markers
The panel below shows the repeat sizes and severity of the disease. Colors indicate normal (green) to severe disease (dark red). With bins the number of repeats can be accurately determined if the fragment size is about 1200 bp.
Repeat Number Interpretation
Table for interpreting GT FA Detector vC results. Size range, repeat numbers, health condition are given.
Sample Profile
Compatibility
This kit is compatible with 5 dyes capillary electrophoresis system such as with ABI 3130/xl, 3500/xL , and SeqStudio Genetic Analyzers and Compact Spectrum CE System with either 30, 50, or 80 capillaries.
This kit can be used on various sources of DNA including DNA extracted from various sources
Kit Content
The kit contains all the necessary reagents and buffers for triplet or normal PCR to be run on either agarose gel or CE system. The kit content includes Primer mix, PCR buffer, GT Extend long DNA Pol in Box A and GT1200 size standard as well as GTM5 v2 Matrix Standard for calibrating the Genetic Analyzer (Box B).
