Key Features and Values
- Proprietary PCR solutions for GC-rich amplification and detection
- Eliminates need for multiple PCRs – one result, straightforward analysis
- Resolves zygosity and detects large expansions
- Fully kitted, end-to-end solutions that significantly reduce hands-on-time
- Sample-to-result possible within a single shift
- Identical PCR and CE conditions as the AmplideX PCR/CE DMPK Kit
- Reliable, unambiguous results and a robust stutter peak pattern
- Accurate sizing across the entire CAG repeat range
- Software converts raw base pair data into number of repeats
The AmplideX PCR/CE HTT Kit is an in vitro nucleic acid amplification kit for the analytical assessment of CAG repeats in exon 1 of the HTT gene. The kit employs PCR on extracted genomic DNA followed by capillary electrophoresis (CE) performed on a laboratory-validated thermal cycler and an Applied Biosystems genetic analyzer, respectively. The kit generates numerical values for alleles up to and including 200 repeats and a categorical value for alleles > 200 repeats.
Huntington disease (HD) is a progressive brain disorder that causes uncontrolled movements, emotional problems, and loss of cognition. Adult-onset HD, the most common form of this disorder, usually appears in a person’s thirties or forties. Individuals with the adult-onset form of HD typically live about 15 to 20 years after signs and symptoms begin. A less common form of HD known as the juvenile form begins in childhood or adolescence. It also involves movement problems and mental and emotional changes. Additional signs of the juvenile form include slow movements, clumsiness, frequent falling, rigidity, slurred speech, and drooling. School performance declines as thinking and reasoning abilities become impaired. Seizures occur in 30 percent to 50 percent of children with this condition. Juvenile HD tends to progress more quickly than the adult-onset form; affected individuals usually live 10 to 15 years after signs and symptoms appear.
Expansions of a CAG trinucleotide repeat in exon 1 of the HTT gene are associated with HD. Normal alleles contain less than 27 CAG repeats. Mutable normal alleles have 27 to 35 CAG repeats, often referred to as the meiotic instability range, or “intermediate alleles” or “mutable normal alleles.” These alleles have yet to be convincingly associated with an HD phenotype; however, they can be meiotically unstable in sperm. With repeats between 36 and 39 individuals may or may not develop the signs and symptoms of HD (i.e. HD alleles with reduced penetrance), whereas those with 40 or more almost always develop the disorder (Bean L and Bayrak-Toydemir P (2014)). The largest known case reported was 250 repeats; however, CAG expansions are rarely observed to be larger than 120 in number.