Biochemical screening of type I collagen in osteogenesis imperfecta: detection of glycine substitutions in the amino end of the alpha chains requires supplementation by molecular analysis
Biochemical screening of type I collagen in osteogenesis imperfecta: detection of glycine substitutions in the amino end of the alpha chains requires supplementation by molecular analysis
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DOI：
10.1136/jmg.2005.040493
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发表时间：
2006-08-01
影响因子：
4
通讯作者：
Marini, J. C.
中科院分区：
文献类型：
--
作者：
Cabral, W. A.;Milgrom, S.;Marini, J. C.
背景：成骨不全症（osteogenesis imperfecta， OI）的生化检测检测到I型胶原螺旋区结构异常，表现为sds -尿素- page上α链的电泳迁移延迟。该测试的灵敏度是基于螺旋中α链的过修饰与甘氨酸取代或其他结构缺陷。可检测的极限尚未报道。方法：我们比较了已知α 1(I)和α a2(I)链氨基酸半部分突变的30个先证者（III型或IV型OI）的胶原电泳迁移。通过5%和6% sds -尿素- page检测敏感性差异，以及α链、沿链位置和取代氨基酸的差异。结果：5%凝胶增强敏感性，细胞内及分泌胶原检查。在a1(I)中，前100个残基中没有检测到替换；目前突变联盟数据库中有7%的病例发生在该地区。残基100和230之间的α 1(I)替换是可变的，而残基232之后的α 1(I)替换都可以检测到。在alpha 2(I)中，电泳检测的可变性延伸到残基436。联盟数据库中约三分之一的病例位于组合变量检测区域。生化敏感性与替代残基无关。结论：ⅰ型胶原生化结果正常的先证者需要补充α 1(I)氨基三分之一和α 2(I)氨基一半的cDNA或gDNA进行分子分析。成骨不全的突变检测对于咨询、生育决策、排除儿童虐待和基因型-表型相关性都很重要。
Background: The biochemical test for osteogenesis imperfecta (OI) detects structural abnormalities in the helical region of type I collagen as delayed electrophoretic migration of alpha chains on SDS-urea-PAGE. Sensitivity of this test is based on overmodification of alpha chains in helices with a glycine substitution or other structural defect. The limits of detectability have not been reported.Methods: We compared the collagen electrophoretic migration of 30 probands ( types III or IV OI) with known mutations in the amino half of the alpha 1(I) and alpha a2(I) chains. Differences in sensitivity were examined by 5% and 6% SDS-urea-PAGE, and with respect to alpha chain, location along the chain, and substituting amino acid.Results: Sensitivity was enhanced on 5% gels, and by examination of intracellular and secreted collagen. In a1( I), substitutions in the first 100 residues were not detectable; 7% of cases in the current Mutation Consortium database are in this region. alpha 1(I) substitutions between residues 100 and 230 were variably detectable, while those after residue 232 were all detected. In alpha 2(I), variability of electrophoretic detection extended through residue 436. About a third of cases in the Consortium database are located in the combined variable detection region. Biochemical sensitivity did not correlate with substituting residue.Conclusions: Complete testing of probands with normal type I collagen biochemical results requires supplementation by molecular analysis of cDNA or gDNA in the amino third of alpha 1(I) and amino half of alpha 2(I). Mutation detection in OI is important for counselling, reproductive decisions, exclusion of child abuse, and genotype-phenotype correlations.