Svejgaard A, Ryder L P
Ann Hum Genet. 1981 Jul;45(3):293-8. doi: 10.1111/j.1469-1809.1981.tb00340.x.
When comparing the odds ratios (OR's) obtained by contrasting various HLA-DR phenotypic classes in patients (e.g. diabetics) and controls, it is desirable to use the same reference phenotypes for all OR's. If this is done, it can be shown that the OR for, say, DR3/4, heterozygotes cannot exceed the OR's for both of the two homozygotes (DR3/3 and DR4/4), if there is one disease susceptibility locus with one normal allele and one susceptibility allele in linkage disequilibrium with two HLA-DR alleles (HLA-DR3 and 4) and if the action of the susceptibility gene is dominant, recessive or intermediate between dominant and recessive. In each of these cases, the OR for the heterozygotes will be intermediate between the OR's of the two homozygotes. If the two alleles at the susceptibility locus act in an overdominant way, the OR for the heterozygotes may in some cases exceed the OR's of both homozygotes. Comparison of the magnitude of two OR-values can be reduced to investigating whether the OR value generated by comparing one phenotypic class against the other (as reference group) differs from unity. There is suggestive but not conclusive evidence that the OR of developing insulin-dependent diabetes for the DR3/4 genotype is higher than the corresponding OR-values for both of the two homozygotes (DR3/3 and DR4/4), indicating that the susceptibility to this disease may not be explained by a dominant, recessive or intermediate model.
在比较通过对比患者（如糖尿病患者）和对照中各种HLA - DR表型类别所获得的优势比（OR）时，所有的OR都使用相同的参考表型是很有必要的。如果这样做，就可以证明，如果存在一个疾病易感基因座，其中一个正常等位基因和一个易感等位基因与两个HLA - DR等位基因（HLA - DR3和4）处于连锁不平衡状态，并且如果易感基因的作用是显性、隐性或介于显性和隐性之间，那么比如说DR3/4杂合子的OR不会超过两个纯合子（DR3/3和DR4/4）的OR。在这些情况中的每一种情况下，杂合子的OR将介于两个纯合子的OR之间。如果易感基因座上的两个等位基因以超显性方式起作用，那么在某些情况下，杂合子的OR可能会超过两个纯合子的OR。两个OR值大小的比较可以简化为研究通过将一个表型类别与另一个（作为参考组）进行比较所产生的OR值是否不同于1。有提示性但非决定性的证据表明，DR3/4基因型患胰岛素依赖型糖尿病的OR高于两个纯合子（DR3/3和DR4/4）相应的OR值，这表明这种疾病的易感性可能无法用显性、隐性或中间模型来解释。
