Cappello N, Restagno G, Garnerone S, Gennaro C, Perugini L, Rendine S, Piazza A, Carbonara A
Dipartimento di Genetica, Biologia e Chimica Medica, Università, Torino, Italy.
Haematologica. 1992 Jul-Aug;77(4):302-6.
The results obtained from a comparative analysis between phenotypic bioassays as the ratio of factor VIII: C clotting activity to factor VIII: C-related antigen, and DNA haplotypes from RFLP's TaqI/St14 and BclI/F8A in 12 hemophilia A (HeA) families are described.
DNA from HeA patients and related at-risk women has been analyzed by Southern blotting with two probes: the intragenic F8A and the extragenic St14. Factor VIII: C coagulant activity was measured by a one-stage method, and the Factor VIII-related antigen (FVIII: RAg) was assayed with bidimensional electrophoresis. Linkage analysis was performed with the LINKAGE computer programs; in particular, the risks of carrying HeA were calculated using the MLINK program.
The observed heterozygosity for the flanking marker DXS 52 (TaqI/St14 RFLP) in combination with intragenic BclI/F8A polymorphism was 0.94. A statistically significant difference in frequency was detected at the DXS 52 locus (allele 4) in comparison with other Caucasian populations. Linkage analysis made it possible to combine the plasma bioassay values with the DNA marker haplotypes to determine the probability of carriership; 22 females at risk were investigated: 4 of them were identified as carriers and 18 were excluded. The risk of carrying hemophilia A for some women at risk in six families is reported.
This study compares a classic method and DNA analysis in genetic counselling for hemophilia A. In some cases the two methods may give different results when identifying carriers in at-risk families. From these data it is possible to conclude that DNA analysis combined with the phenotypic bioassays for carrier detection gives more information that the two analyses taken separately.
本文描述了对12个甲型血友病（HeA）家庭进行的比较分析结果，该分析涉及作为因子VIII：C凝血活性与因子VIII：C相关抗原比值的表型生物测定，以及来自RFLP的TaqI/St14和BclI/F8A的DNA单倍型。
采用两种探针通过Southern印迹法分析HeA患者及其相关高危女性的DNA：基因内F8A和基因外St14。采用一步法测定因子VIII：C凝血活性，用双向电泳法测定因子VIII相关抗原（FVIII：RAg）。使用LINKAGE计算机程序进行连锁分析；特别是，使用MLINK程序计算携带HeA的风险。
侧翼标记DXS 52（TaqI/St14 RFLP）与基因内BclI/F8A多态性的观察杂合度为0.94。与其他白种人群相比，在DXS 52位点（等位基因4）检测到频率有统计学显著差异。连锁分析使得将血浆生物测定值与DNA标记单倍型相结合以确定携带者概率成为可能；对22名高危女性进行了调查：其中4人被确定为携带者，18人被排除。报告了六个家庭中一些高危女性携带甲型血友病的风险。
本研究比较了甲型血友病遗传咨询中的经典方法和DNA分析。在某些情况下，在识别高危家庭中的携带者时，这两种方法可能会给出不同的结果。从这些数据可以得出结论，DNA分析与用于携带者检测的表型生物测定相结合比单独进行这两种分析能提供更多信息。
