The epidemiological study was retrospective, data was optained from the Department of Cytogenetics, and the number of boys with full mutation in the gene was compared with the figures from Hagstofa Íslands on the number of live births of boys born during the years.
Faraldsfræðirannsóknin var afturskyggn, en í henni voru upplýsingar úr rannsóknarskrám litningarannsóknadeildar notaðar til að bera saman fjölda drengja með fulla stökkbreytingu í geninu við tölur frá Hagstofu Íslands um fjölda lifandi fæddra drengja fæddra á sama árabili.