von Kaisenberg C S, Caliebe A, Krams M, Hackelöer B J, Jonat W
University Hospital, Department of Obstetrics and Gynaecology, Kiel, Germany.
Am J Med Genet. 2000 Dec 18;95(5):425-8.
We report on a female fetus with partial trisomy 9 due to a reciprocal translocation in the mother. Routine ultrasound examination at 23 weeks showed hypoplasia of the cerebellar vermis, dilated foramen Magendii, and dilatation of the cisterna magna. Due to the poor prognosis, the parents opted for termination of pregnancy. A postmortem examination confirmed caudal hypoplasia and dysplasia of the cerebellar vermis, resulting in a massively dilated foramen Magendii through which the enlarged cisterna magna communicated with the fourth ventricle. There was also micropolygyria indicating migration disorder. Cytogenetic studies showed a 47,XX,+der(9)t(7;9) (q35;q22.2)mat karyotype. Investigation of the parents revealed a translocation (7;9) (q35;q22.2) in the mother and a normal male karyotype in the father. We systematically searched the chromosome 9 gene map for genes that were trisomic in our fetus and genes that were located on the regions that had the normal two copies of genes. Genes that could potentially be involved in the formation of the Dandy-Walker phenotype are transcription factors or genes responsible for the regulation of normal in particular cerebral development but also adhesion molecules. We conclude that one cause for Dandy-Walker malformation could be a gene dosage effect of genes located on 9pter-9q22. In addition, it seems that absence of trisomy 9 in q22-pter does not prevent abnormal cerebellar development.
我们报告了一例因母亲发生相互易位导致部分9号染色体三体的女性胎儿。孕23周时的常规超声检查显示小脑蚓部发育不全、马让迪孔扩大及小脑延髓池增宽。鉴于预后不良，父母选择终止妊娠。尸检证实存在尾部发育不全及小脑蚓部发育异常，导致马让迪孔大幅扩大，扩大的小脑延髓池经此与第四脑室相通。还存在微小多脑回，提示神经元移行障碍。细胞遗传学研究显示核型为47,XX,+der(9)t(7;9)(q35;q22.2)mat。对父母的检查发现母亲存在(7;9)(q35;q22.2)易位，父亲核型正常。我们系统地在9号染色体基因图谱中查找在我们的胎儿中呈三体状态的基因以及位于具有正常两份基因拷贝区域的基因。可能参与丹迪-沃克表型形成的基因是转录因子或负责调节正常尤其是脑发育的基因以及黏附分子。我们得出结论，丹迪-沃克畸形的一个原因可能是位于9pter - 9q22的基因的基因剂量效应。此外，9号染色体q22 - pter区域不存在三体似乎并不妨碍小脑的异常发育。
