Detection of expanded nucleotide repeat sequences of causative gene in patients with hereditary spinocerebellar ataxia / 中华神经医学杂志

Objective To determine a stable, exact and direct detection method for expanded nucleotide repeat sequences of the causative gene in patients with hereditary spinocerebellar ataxias (SCAs).Methods Quantitative fluorescent-polymerase chain reaction,8%denaturing polyacrylamide gel electrophoresis(PAGE),capillary electrophoresis(CE)and recombinant DNA technology by direct sequencing technique were employed to detect the CAG-repeat numbers of abnormal allele in 50 patients diagnosed as having SCA3/MJD.And then,the differences of CAG repeat numbers detected by CE and recombinant DNA technology were statistically analyzed.Results Of the 50 patients with SCA3/MJD detected by 8%denaturing PAGE,the expanded CAG repeat numbers measured by CE and recombinant DNA technology ranged from 63 to 74(69.56±2.12)and from 67 to 80(73.72±3.29),respectively.Significantly decreasedtendency was showed in the mean CAG repeat numbers of 69.56±2.12 using CE as compared with that in those of 73.72±3.29 using recombinant DNA technology,(t=-9.61,P=0.000). Conclusion Denaturing PAGE and CE can be used as preliminary screening for nucleotide repeat numbers,while the exact numbers depend on the recombinant DNA and direct sequencing technologies.Recombinant DNA technology combined with direct sequencing is a predominant,stable,exact and direct method to detect the repeat numbers of SCAs and analyze the polymorphism of nucleotide sequence.

Polynucleotide repeat expansion of nine spinocerebellar ataxia subtypes and dentatorubral-pallidoluysian atrophy in healthy Chinese Han population / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To assist the establishment of platform and provide the reference standard for mutation detection in spinocerebellar ataxia (SCA) subtypes 1, 2, 3, 6, 7, 8, 10, 12, 17 and dentatorubral-pallidoluysian atrophy (DRPLA) in Chinese Han population.</p><p><b>METHODS</b>The nucleotide repeat numbers of the 9 SCA subtypes and DRPLA were detected using fluorescence-PCR and capillary gel electrophoresis technique in 300 healthy Chinese Han individuals.</p><p><b>RESULTS</b>Among the 300 healthy controls, the range of the CAG trinucleotide repeat number was 17 to 35 in SCA1, 14-28 in SCA2, 13-41 in SCA3/MJD, 4-16 in SCA6, 5-17 in SCA7, 5-21 in SCA12, 23-41 in SCA17, and 12-33 in DRPLA; and the range of CTA/CTG trinucleotide repeat number on SCA8 locus was 12-43 and the range of ATTCT pentanucleotide repeat number on SCA10 locus was 9-32. Of which, the 12 CTA/CTG repeats of SCA8, 9 ATTCT repeats of SCA10, 23 CAG repeats of SCA17 were the shortest normal repeat number, while the 41 CAG repeats of SCA3/MJD, 32 CAG repeats of SCA10 were the largest normal number that have not been reported.</p><p><b>CONCLUSION</b>The normal ranges of polynucleotide repeats of different subtypes of SCA vary with geographical areas and ethnicities. It might be associated with the genetic and ethnic backgrounds. This is the first normal reference standard of polynucleotide repeat number of these ten SCA subtypes in Chinese Han.</p>

Detection of the CAG trinucleotide repeats of MJD1 gene by recombinant DNA technology / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To establish a stable, accurate and intuitive method for detecting the CAG trinucleotide repeats of MJD1 gene.</p><p><b>METHODS</b>The CAG trinucleotide polymorphism of the MJD1 gene was analyzed by recombinant DNA technology and DNA sequencing in 35 spinocerebellar ataxia 3/Machado-Joseph disease (SCA3/MJD) patients from Mainland China.</p><p><b>RESULTS</b>The range of the CAG repeat of the 35 patients was 65-81 (mean = 72.96 +/- 4.24). The CAG repeats contained two CAAs and one AAG variations in the CAG motif in all the patients and majority of the healthy controls. There was a CGG/GGG polymorphism at the 3' end of the CAG repeat. The GGG allele was consistently associated with smaller CAG repeats in healthy controls. On the other hand, the CGG allele consistently existed in the patients.</p><p><b>CONCLUSION</b>Recombinant DNA technology can stably, accurately and intuitively detect the CAG trinucleotide repeat of the MJD1 gene. It should be used as a major technique to diagnose the SCA3/MJD and analyze the polymorphism of CAG sequence.</p>