Webb T, Jacobs P A
Department of Clinical Genetics, Birmingham Maternity Hospital.
J Med Genet. 1990 Oct;27(10):627-31. doi: 10.1136/jmg.27.10.627.
X inactivation studies have been carried out on lymphocytes from eight unrelated females heterozygous for the Martin-Bell syndrome. Four of these carriers were of normal IQ and four were mentally handicapped. When BrdU was used to differentiate between the active and inactive X chromosome an average of 55% of fra(X) were active in the retarded subjects, but only 27% were active in those of normal IQ. When 3H thymidine was used to differentiate between the active and inactive X chromosome, an average of 58% of mitoses from handicapped subjects and 33% of mitoses from normal subjects showed an active fra(X) in informative cells. These results are compared with previously published studies and it is concluded that the number of inactive fra(X) chromosomes calculated as a proportion of all cells scored is the same in mentally normal and mentally retarded subjects. However, the number of active fra(X) chromosomes is consistently higher in the retarded than in the normal females.
对八名患有马丁 - 贝尔综合征的无关杂合子女性的淋巴细胞进行了X染色体失活研究。其中四名携带者智商正常，四名有智力障碍。当使用溴脱氧尿苷（BrdU）区分活性和非活性X染色体时，在智力发育迟缓的受试者中，平均55%的脆性X染色体（fra(X)）是活性的，但在智商正常的受试者中只有27%是活性的。当使用3H胸腺嘧啶核苷区分活性和非活性X染色体时，在信息细胞中，平均58%的智力障碍受试者的有丝分裂和33%的正常受试者的有丝分裂显示出活性的fra(X)。将这些结果与先前发表的研究进行了比较，得出的结论是，以所有计分细胞的比例计算，智力正常和智力发育迟缓的受试者中失活的fra(X)染色体数量相同。然而，智力发育迟缓女性中活性fra(X)染色体的数量始终高于正常女性。
