Peyser Alexandra, Singer Tomer, Mullin Christine, Hershlag Avner
Department of Obstetrics and Gynecology, Northwell Health, Division of Reproductive Endocrinology, Hofstra-Northwell School of Medicine, New York, USA.
JBRA Assist Reprod. 2017 Dec 1;21(4):327-329. doi: 10.5935/1518-0557.20170054.
CGG repeat expansion on the fragile X mental retardation 1 (FMR1) gene is used to diagnose fragile X syndrome. Previous studies have discussed the correlation between the number of CGG repeats and its associated phenotypic components. The objective of this study is to determine whether the number of CGG repeats differ between carriers of genetic disorders versus noncarriers.
We performed a retrospective chart review of 2867 patients who received genetic screening at our fertility clinic between June 2013 and July 2015. The number of CGG repeats on allele 1 and allele 2 on the FMR1 gene was collected and it was specified whether the patient was a carrier or a noncarrier of a specific mutation. Patients with CGG repeats greater than or equal to 45 were excluded from the study.
Carriers (n=759) had a reduced number of repeats compared to noncarriers (n=2024) on allele 1 (p=.03), allele 2 (p=.02) and the average of both alleles (p=.01). Additionally, the number of CGG repeats from the ten most carried diseases from the cohort were used and tested individually for clinical significance against the number of repeats in the noncarriers. A reduction in repeats was shown in several mutations and a few were outliers.
Our results demonstrate that there is a significant reduction in the number of CGG repeats in carriers of genetic mutations. A larger scale study of disease carrying patients would be beneficial.
脆性X智力低下1（FMR1）基因上的CGG重复扩增用于诊断脆性X综合征。以往研究讨论了CGG重复次数与其相关表型成分之间的相关性。本研究的目的是确定遗传病携带者与非携带者之间CGG重复次数是否存在差异。
我们对2013年6月至2015年7月在我们生育诊所接受基因筛查的2867例患者进行了回顾性病历审查。收集FMR1基因等位基因1和等位基因2上的CGG重复次数，并明确患者是特定突变的携带者还是非携带者。CGG重复次数大于或等于45的患者被排除在研究之外。
与非携带者（n = 2024）相比，携带者（n = 759）在等位基因1（p = 0.03）、等位基因2（p = 0.02）以及两个等位基因的平均值（p = 0.01）上的重复次数减少。此外，使用队列中携带率最高的十种疾病的CGG重复次数，并分别针对非携带者的重复次数测试其临床意义。在几种突变中显示重复次数减少，少数为异常值。
我们的结果表明，基因突变携带者的CGG重复次数显著减少。对携带疾病患者进行更大规模的研究将是有益的。
