June 24, 2009

Here's an interesting study that takes advantage of recorded parentage data from people with MS with mixed-race parents to see what effect different ancestries may have on risk of MS. A research team searched a gigantic database of 30,000 MS families and found 58 families where people with MS had one Native American parent and one Caucasian parent. The team performed some comparisons between the 27 families where the father was Native American and the mother Caucasian, and the 31 families where the ancestry was reversed. They found no difference in the ratios of female:male children overall; however, in just the children with MS, the female:male ratio was much higher when the mother was Caucasian and the father Native American than when the parentage was reversed (7:1 vs. 2:1). No differences between the two groups was seen in terms of clinical course or age at onset.

Why would the ethnicity of the parents affect the MS sex ratio in these interracial families? The authors didn't have an answer for that but suggested that it might be due to different exposures to environmental factors, and/or how these interact with genetic factors.