Kennerknecht I, Barbi G, Dahl N, Steinbach P
Abteilung Klinische Genetik, Universität Ulm, Federal Republic of Germany.
Am J Med Genet. 1991 Feb-Mar;38(2-3):467-75. doi: 10.1002/ajmg.1320380266.
We report on 12 prenatal diagnoses performed between weeks 10 and 13 on normal women with a well-documented family history of the Martin-Bell syndrome. Seven were obligate and three were potential carriers. One male and 2 female fetuses were found to be fragile X [fra(X)]-positive. The diagnoses were confirmed in fibroblasts or lymphocytes after interruption or postnatally. In one fra(X)-negative female fetus, the analysis of linked DNA markers indicated that most probably she was a heterozygote. Reexamination after birth gave a fra(X)-positive result. Hence this was a case of a false-negative prenatal fra(X) result. The occurrence of false-negative cytogenetic results represents a common problem that limits the sensitivity of prenatal diagnostics in the Martin-Bell syndrome. A study of linked DNA markers can improve the reliability of negative cytogenetic results in first trimester prenatal diagnosis. In case of doubt, the chromosomes could be reexamined after fetal blood sampling.
我们报告了对10至13周之间具有马丁-贝尔综合征明确家族病史的正常女性进行的12例产前诊断。其中7例为肯定携带者，3例为可能携带者。发现1例男性胎儿和2例女性胎儿脆性X[fra(X)]阳性。诊断在终止妊娠后或出生后在成纤维细胞或淋巴细胞中得到证实。在1例fra(X)阴性的女性胎儿中，对连锁DNA标记的分析表明她很可能是杂合子。出生后复查结果为fra(X)阳性。因此，这是一例产前fra(X)假阴性结果的病例。细胞遗传学假阴性结果的出现是一个常见问题，限制了马丁-贝尔综合征产前诊断的敏感性。对连锁DNA标记的研究可以提高孕早期产前诊断中细胞遗传学阴性结果的可靠性。如有疑问，可在采集胎儿血样后重新检查染色体。
