Migraine without aura: A population-based twin study

To investigate the importance of genetic and environmental factors to the e tiology of migraine without aura and to compare the symptomatology of migra ine without aura in monozygotic and dizygotic twins, 2,680 twin pairs were recruited from the population-based Danish Twin Registry. Monozygotic (MZ) and same-sex dizygotic (DZ) twin pairs, where at least one twin had self-re ported migraine or self-reported severe headache with accompanying symptoms , were telephone interviewed by a physician. The participation rate in the telephone interview was 90%. The pairwise concordance rate was significantl y higher in MZ than in DZ twin pairs (28% vs 18%). The proband arise concor dance rate was 40% (95% CI, 33-48%) in MZ and 28% (95% CI, 23-33%) in DZ tw in pairs. The pairwise concordance rates for the different pain characteris tics and accompanying symptoms were not significantly different in MZ and D Z twin pairs. however, comparing all of the pairwise concordance rates of p ain characteristics and accompanying symptom together, MZ twin pairs were s ignificantly more concordant than DZ twin pairs. Our data demonstrate a sig nificant genetic factor in migraine without aura. The size of this factor i s modest and the demonstration of susceptibility genes is predicted to be l aborious and difficult.