Martin N G, Kehren U, Battistutta D, Mathews J D
Queensland Institute of Medical Research, Brisbane, Australia.
Acta Genet Med Gemellol (Roma). 1991;40(2):165-72. doi: 10.1017/s0001566000002609.
In 1980-82, a mailed questionnaire was completed by 3,810 pairs of adult twins enrolled on the Australian NH&MRC Twin Register. Twins were asked whether they had had their tonsils out and, if so, at what age. The sample was divided into four birth cohorts of approximately equal size, and only childhood tonsillectomy (to the age of 18) was considered. The prevalence of tonsillectomy differed markedly between cohorts, being highest in those born in the 1940s and early 1950s. Within each cohort, the prevalence was very similar in MZ and DZ twins, yet concordance was much higher in MZ twins, indicating the importance of genetic factors in predisposition to tonsillectomy. However, the proportions of variance in liability due to genetic and shared environmental factors differed markedly between cohorts. In the 1950s, when tonsillectomy was fashionable, shared environment accounted for 60% of variance and genetic factors for only 29%. However, by the early 1960s, when tonsillectomy was going out of fashion, heritability was up to 0.82 and shared environment accounted for only 10% of variance. Our results illustrate, once again, that heritability is not a constant, but depends on the precise characteristics of the population and the time at which it is studied.
1980年至1982年期间，澳大利亚国家卫生与医学研究理事会双胞胎登记处登记的3810对成年双胞胎完成了一份邮寄问卷调查。双胞胎被问及是否切除过扁桃体，如果切除过，是在什么年龄切除的。样本被分为四个规模大致相等的出生队列，并且仅考虑儿童期扁桃体切除术（至18岁）。各队列之间扁桃体切除术的患病率差异显著，在20世纪40年代和50年代初出生的人群中患病率最高。在每个队列中，同卵双胞胎和异卵双胞胎的患病率非常相似，但同卵双胞胎的一致性要高得多，这表明遗传因素在扁桃体切除易感性中的重要性。然而，不同队列中由遗传因素和共享环境因素导致的易感性差异比例明显不同。在20世纪50年代，当扁桃体切除术很流行时，共享环境占差异的60%，遗传因素仅占29%。然而，到20世纪60年代初，当扁桃体切除术不再流行时，遗传度高达0.82，共享环境仅占差异的10%。我们的结果再次表明，遗传度不是一个常数，而是取决于所研究人群的精确特征以及研究的时间。
