Jenkins E C, Genovese M J, Duncan C J, Gu H, Stark-Houck S L, Lele K, Li S Y, Krawczun M S
Department of Genetics, New York State Institute for Basic Research in Developmental Disabilities, Staten Island 10314.
Am J Med Genet. 1992;43(1-2):136-41. doi: 10.1002/ajmg.1320430121.
Cell cultures from 760 whole blood, amniotic fluid, chorionic villus sample, and peripheral umbilical blood sample specimens were exposed to multiple fra(X)(q27.3) induction systems (none had aphidicolin). Fifty-three exhibited the rare fragile site, fra(X)(q27.3) or FRAXA, none of which demonstrated the common fragile site or FRAXD at band Xq27.2. Only one cell in one of the negative whole blood FUdR-treated cultures from a mentally retarded male showed FRAXD. Therefore, it appears that FRAXD occurs very rarely in cultures treated to induce FRAXA since only one positive cell was observed in over 88,000 analyzed. It appears that very low frequencies of fra(X)(q27) can be accounted for only in part by the presence of the common fragile site since only one of 9 cases, each with one fra(X)(q27) positive cell, exhibited FRAXD and the others were FRAXA. After confirmation of FRAXA with direct DNA testing in a large number of low frequency cases, it should be possible to rely on the detection of very low frequencies of fra(X)(q27.3), e.g., 1% with at least 2 positive cells.
来自760份全血、羊水、绒毛膜绒毛样本和外周脐血样本的细胞培养物被暴露于多种fra(X)(q27.3)诱导系统（均不含阿非科林）。53个样本表现出罕见的脆性位点fra(X)(q27.3)或FRAXA，其中没有一个在Xq27.2带显示常见的脆性位点或FRAXD。在一名智力迟钝男性的阴性全血FUdR处理培养物中，只有一个细胞显示出FRAXD。因此，似乎FRAXD在用于诱导FRAXA的培养物中非常罕见，因为在超过88,000个分析细胞中仅观察到一个阳性细胞。似乎fra(X)(q27)的极低频率仅部分可归因于常见脆性位点的存在，因为9例中每例有一个fra(X)(q27)阳性细胞，只有1例表现出FRAXD，其他为FRAXA。在大量低频病例中通过直接DNA检测确认FRAXA后，应该能够依靠检测fra(X)(q27.3)的极低频率，例如至少有2个阳性细胞时为1%。
