Syrrou M, Patsalis P C, Georgiou I, Hadjimarcou M I, Constantinou-Deltas C D, Pagoulatos G
Laboratory of General Biology, Medical School, University of Ioannina, Greece.
Am J Med Genet. 1996 Jul 12;64(1):234-8. doi: 10.1002/(SICI)1096-8628(19960712)64:1<234::AID-AJMG42>3.0.CO;2-L.
The expansion of the trinucleotide repeat (CGG)n in successive generations through maternal meiosis is the cause of fragile X syndrome. Analysis of CA repeat polymorphisms flanking the FMR-1 gene provides evidence of a limited number of "founder" chromosomes and predisposing high-risk haplotypes related to the mutation. To investigate the origin of mutations in the fragile X syndrome in the Hellenic populations of Greece and Cyprus, we studied the alleles and haplotypes at DXS548 and FRAXAC2 loci of 16 independent fragile X and 70 normal control chromosomes. In addition, we studied 191 unrelated normal X chromosomes for the distribution and frequencies of CGG alleles. At DXS548, 6 alleles were found, 2 (194 and 196) of which were represented on fragile X chromosomes. At FRAXAC2, 6 alleles were found, 4 of which were present on fragile X chromosomes. Sixteen haplotypes were identified, but only 5 were present on fragile X chromosomes. The highest number of CGG repeats (> or = 33) were associated with haplotypes 194-147, 194-151, 194-153, and 204-155. The data provide evidence for founder chromosomes and high-risk haplotypes in the Hellenic population.
通过母系减数分裂，三核苷酸重复序列（CGG）n在连续几代中的扩增是脆性X综合征的病因。对FMR-1基因侧翼的CA重复多态性进行分析，为有限数量的“奠基者”染色体以及与该突变相关的易患高风险单倍型提供了证据。为了研究希腊和塞浦路斯希腊人群中脆性X综合征突变的起源，我们研究了16条独立的脆性X染色体和70条正常对照染色体在DXS548和FRAXAC2位点的等位基因和单倍型。此外，我们研究了191条不相关的正常X染色体上CGG等位基因的分布和频率。在DXS548位点，发现了6个等位基因，其中2个（194和196）出现在脆性X染色体上。在FRAXAC2位点，发现了6个等位基因，其中4个出现在脆性X染色体上。鉴定出16种单倍型，但只有5种出现在脆性X染色体上。CGG重复序列数量最多（≥33）的与单倍型194-147、194-151、194-153和204-155相关。这些数据为希腊人群中的奠基者染色体和高风险单倍型提供了证据。
