Hulsebos T J, Bijlsma E K, Geurts van Kessel A H, Brakenhoff R H, Westerveld A
Institute of Human Genetics, University of Amsterdam, The Netherlands.
Cytogenet Cell Genet. 1991;56(3-4):171-5. doi: 10.1159/000133080.
We have isolated a human probe specific for the beta B3 crystallin gene (CRYB3) and hybridized it to Southern blots of human X rodent cell hybrids with known human chromosomal constitution. In this way we could directly assign CRYB3 to chromosome 22. Cell hybrids with translocation chromosomes containing distinct portions of chromosomes 22 were used to regionally localize the gene to 22q11.2----q12. Owing to its known close proximity to the beta B3 crystallin gene, the beta B2-1 crystallin gene (CRYB2-1) also maps in this region. A second beta B2 crystallin gene, beta B2-2 (CRYB2-2), not linked to the CRYB2-1/CRYB3 cluster, could be localized in the same region. This implies that the three known beta B crystallin genes are all within 22q11.2----q12. This small region contains D22S1, the only marker that shows no recombination with neurofibromatosis 2. Therefore, the beta B crystallin genes on chromosome 22 might be markers for this disease. Two DNA fragments revealing useful polymorphisms associated with the beta B crystallin genes were identified. One detects a two-system MspI restriction fragment length polymorphism specific for the CRYB2-1/CRYB3 cluster. The other detects an informative PstI polymorphism that is in linkage equilibrium with the MspI polymorphism.
我们分离出了一种针对βB3晶状体蛋白基因（CRYB3）的人类探针，并将其与已知人类染色体组成的人-啮齿动物细胞杂种的Southern印迹杂交。通过这种方式，我们可以直接将CRYB3定位到22号染色体上。利用含有22号染色体不同部分的易位染色体的细胞杂种，将该基因区域定位到22q11.2----q12。由于已知βB2-1晶状体蛋白基因（CRYB2-1）与βB3晶状体蛋白基因紧密相邻，它也定位于该区域。第二个βB2晶状体蛋白基因，βB2-2（CRYB2-2），不与CRYB2-1/CRYB3基因簇连锁，也可定位在同一区域。这意味着三个已知的βB晶状体蛋白基因都在22q11.2----q12范围内。这个小区域包含D22S1，这是唯一与神经纤维瘤病2没有重组的标记。因此，22号染色体上的βB晶状体蛋白基因可能是这种疾病的标记。鉴定出了两个与βB晶状体蛋白基因相关的有用多态性的DNA片段。一个检测到针对CRYB2-1/CRYB3基因簇的双系统MspI限制性片段长度多态性。另一个检测到一个信息丰富的PstI多态性，它与MspI多态性处于连锁平衡状态。
