FREQUENCY OF FMR1 PREMUTATIONS IN A CONSECUTIVE NEWBORN POPULATION BY PCR SCREENING OF GUTHRIE BLOOD SPOTS
FREQUENCY OF FMR1 PREMUTATIONS IN A CONSECUTIVE NEWBORN POPULATION BY PCR SCREENING OF GUTHRIE BLOOD SPOTS
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DOI：
10.1006/bmme.1995.1057
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发表时间：
1995-10-01
期刊：
影响因子：
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通讯作者：
CHUDLEY, AE
中科院分区：
文献类型：
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作者：
DAWSON, AJ;CHODIRKER, BN;CHUDLEY, AE
脆性X(A)或FRAXA综合征是家族性智力低下的最常见形式，与Xq27.3的脆弱位点有关。导致FRAXA综合征的基因FMR1基因已经被克隆。FMR1基因的失活与三核苷酸CGG重复序列的扩增和邻近CpG岛的甲基化有关。先前对FRAXA综合征患病率的估计是基于机构和社区工作坊中对智力障碍的染色体分析的间接方法。我们在一项匿名、无关联的调查中分析了1000名男性和1000名女性连续新生儿非高压灭菌血点的3002个X染色体中FMR1基因的前突变频率，通过变性测序凝胶法测量PCR反应产物的长度来计算CGG重复序列的大小。为了获得一致的PCR扩增，需要进行DNA微萃取，包括苯酚/氯仿系列。在我们的人群中，CGG等位基因在9到106个重复之间；97%的等位基因重复次数少于40次，最常见的等位基因重复次数为28次。约2.3%的等位基因的CGG重复数在4 ~ 49之间，0.37%的等位基因的重复数在50 ~ 59之间。在马尼托巴省男性人群中，bbb60等位基因的重复频率约为0.13%。不推荐使用非高压灭菌的Guthrie血点进行FRAXA前突变的人群筛查，苯酚/氯仿DNA微提取的必要性是繁琐和耗时的。DNA的低产量（250 ng）不允许Southern对40-60次重复范围内具有潜在不稳定CGG等位基因的明显纯合子雌性进行重新分析，并且可能低估了突变前的携带者状态。(C) 1995学术出版社，Inc。
The fragile X(A) or FRAXA syndrome is the most common form of familial mental retardation and is associated with a fragile site at Xq27.3. The gene responsible for the FRAXA syndrome, the FMR1 gene, has been cloned. Inactivation of the FMR1 gene is associated with amplification of a trinucleotide CGG repeat sequence and methylation of an adjacent CpG island, Previous estimates for the prevalence of the FRAXA syndrome have been based on indirect methods of chromosome analysis in institutions and community workshops for the mentally handicapped. We have analyzed the frequency of premutations of the FMR1 gene in 3002 X chromosomes of 1000 male and 1000 female consecutive newborn nonautoclaved blood spots in an anonymous, unlinked survey, The CGG repeat sizes were calculated by measuring the length of products of the PCR reaction based on the molecular size of labeled markers in a denaturing sequencing gel assay. For consistent PCR amplification a DNA microextraction was necessary, including a phenol/ chloroform series. In our population, the CGG allele ranged from 9 to 106 repeats; 97% of alleles had fewer than 40 repeats, The most frequent allele was a repeat of 28. Approximately 2.3% of alleles had CGG repeats ranging from 4 to 49 and 0.37% of alleles had repeats ranging from 50 to 59. The frequency of alleles >60 repeats in the Manitoba male population is approximately 0.13%. The use of nonautoclaved Guthrie blood spots for population screening of FRAXA premutations is not recommended, The necessity of a phenol/chloroform DNA microextraction is tedious and time consuming. The low yield of DNA (250 ng) does not allow for reanalysis by Southern of apparently homozygous females with potentially unstable CGG alleles in the 40-60 repeat range and likely underestimates premutation carrier status. (C) 1995 Academic Press, Inc.