puzzled by trinucleotide repeats test

[junchen]

The trinucleotide repeats are resposible for Huntington's disease and fragile X syndrome. Huntington's : normal-less than 27 'CAG' repeats disorder-more than 39 'CAG' repeats. fragile X syndrome : normal- 21 to 31 'CGG' repeats, disorder- more than 200 'CGG'. Anybody can tell me which instrument(next-generation equipment) is best for this specific gene test?

[ECO]

Hey Junchen

If this is indeed a legitimate post, it doesn't belong in Bioinformatics. I'll be moving it to General.

Also, the best instrument for this test is PCR.

[Michael.James.Clark]

The trinucleotide repeats are resposible for Huntington's disease and fragile X syndrome. Huntington's : normal-less than 27 'CAG' repeats disorder-more than 39 'CAG' repeats. fragile X syndrome : normal- 21 to 31 'CGG' repeats, disorder- more than 200 'CGG'. Anybody can tell me which instrument(next-generation equipment) is best for this specific gene test?

454 is the only one currently prevalent that can handle sequences that long reliably. If you try sequencing these with 100bp Solexa or 50bp SOLiD reads, you'll end up getting lost inside the repeats.

As for PCR being more useful, I think it depends on your number of samples and application. If it's just for diagnostics, PCR should be sufficient.

If it's for a larger study where you want the precise number of trinucleotide repeats in a large number of samples, a 454 approach might be more effective.