Zergollern-Cupak L, Sabol Z, Hitrec V, Vuković J, Medica I
Klinika za djecje bolesti, Medicinski fakultet Sveucilista u Zagrebu.
Lijec Vjesn. 1990 Nov-Dec;112(11-12):393-6.
Fra (X) or Martin-Bell syndrome is the most common X-linked mental retardation with an incidence of 1/1000-2000 newborns. Chromatid break, double chromatid break or total loss of distal part of X chromosome (which occurs most often inside the C positive band q 27.3) is demonstrated in most male hemizygotes as mental retardation and specific phenotypic features. Fra (X) syndrome is proved in the cultured lymphocytes or fibroblasts with special cytogenetic methods. The prenatal diagnosis is possible by examining of amniotic fluid or the lymphocytes from the umbilical cord. We report two families with fra (X) syndrome. In the first one, 6 year- and 9-month-old boy with mental retardation and characteristic phenotypic features has been recognized as the carrier of fra (X) syndrome and after that his 4-year-old brother with similar symptoms. In the second family, there is a severe mentally retarded 3-year-old boy with fra (X) syndrome who besides typical phenotipic changes also exhibits symptoms of autism. The percentage of the cells with fra (X) chromosome in our patients (30%, 28%, 18%) is not correlated with the degree of their mental retardation. The mothers of our patients are the heterozygous carriers of the syndrome (3% and 1.5% fra (X) chromosome).
脆性X综合征或马丁-贝尔综合征是最常见的X连锁智力障碍，发病率为1/1000 - 2000新生儿。在大多数男性半合子中可观察到染色单体断裂、双染色单体断裂或X染色体远端部分完全缺失（最常发生在C阳性带q27.3内），表现为智力障碍和特定的表型特征。通过特殊的细胞遗传学方法在培养的淋巴细胞或成纤维细胞中可证实脆性X综合征。通过检查羊水或脐带血中的淋巴细胞可进行产前诊断。我们报告了两个患有脆性X综合征的家庭。在第一个家庭中，一名6岁9个月大、患有智力障碍和特征性表型特征的男孩被确认为脆性X综合征携带者，之后他4岁的弟弟也出现了类似症状。在第二个家庭中，有一名患有脆性X综合征的3岁重度智障男孩，除了典型的表型变化外，还表现出自闭症症状。我们患者中具有脆性X染色体的细胞百分比（30%、28%、18%）与他们的智力障碍程度无关。我们患者的母亲是该综合征的杂合子携带者（脆性X染色体比例分别为3%和1.5%）。
