Brackenridge C J
J Med Genet. 1974 Jun;11(2):136-40. doi: 10.1136/jmg.11.2.136.
The birth ranks and parental ages at birth of subjects affected with Huntington's disease were ascertained from the literature and examined in relation to the neurological sign displayed (muscular rigidity or choreo-athetosis). With respect to the sex of the affected parent, the percentage of rigid cases was found to decrease linearly with advancing paternal age and to increase linearly with advancing maternal age. In contrast, no significant relation was found for birth rank or for age of the unaffected parent. The results could be explained in terms of the somatic gene-mutation theory of Burch by invoking a `switching mechanism' which converts a predisposing autosomal allele for rigidity in the germ cell of affected fathers into one which is expressed as chorea. The converse mechanism is postulated to occur in affected mothers. Calculation showed that the hypothetical mutation rates were of the same magnitude in affected parents of each sex.
亨廷顿舞蹈病患者的出生顺序及出生时父母的年龄是从文献中确定的，并根据所表现出的神经学体征（肌肉强直或舞蹈指划动作）进行了检查。就患病父母的性别而言，发现强直病例的百分比随父亲年龄的增长呈线性下降，随母亲年龄的增长呈线性上升。相比之下，未发现出生顺序或未患病父母的年龄有显著关系。根据伯奇的体细胞基因突变理论，通过引入一种“转换机制”可以解释这些结果，该机制将患病父亲生殖细胞中一个导致强直的常染色体等位基因转换为一个表现为舞蹈病的等位基因。推测相反的机制发生在患病母亲身上。计算表明，假设的突变率在每种性别的患病父母中幅度相同。
