—Grufferman and Cole are correct that I misunderstood the tabulation in Grufferman et al1 of the number of like-sex and unlike-sex sibling pairs affected with Hodgkin's disease. As a result I failed to include 13 of the pairs in my reanalysis of the data that they summarized.In their analysis Grufferman et al1 calculated the expected proportion of sex-concordant sibling pairs based on the sex ratio in a random population of patients with Hodgkin's disease, whereas I used the sex ratio in the affected siblings per se. The latter expectation seems preferable, since the sex ratio in random cases may differ from the sex ratio in familial cases. For MS there was a decline in the female to male ratio from 2:1 in random cases to 1.5:1 in 130 sibships with two affected siblings, and to 1:1 in 15 sibships with three affected sidlings.2 This observation suggested
Weitkamp LR. Interaction Between Sex and HLA Type in Hodgkin's Disease-Reply. Arch Neurol. 1984;41(8):816. doi:10.1001/archneur.1984.00510430018006
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