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Is the genetic liability in multifactorial disorders higher in concordant than discordant monozygotic twin pairs? A population‐based family twin study of migraine without aura
Author(s) -
Gervil M.,
Ulrich V.,
Kaprio J.,
Russell M. B.
Publication year - 2001
Publication title -
european journal of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 124
eISSN - 1468-1331
pISSN - 1351-5101
DOI - 10.1046/j.1468-1331.2001.00188.x
Subject(s) - medicine , migraine , aura , migraine with aura , twin study , monozygotic twin , population , familial hemiplegic migraine , psychiatry , genetics , heritability , environmental health , biology
Migraine without aura (MO) is a multifactorial disorder. Expression of a disorder with multifactorial inheritance depends on the genetic liability and on environmental factors. A high liability is reflected by a high frequency of affected relatives. We have previously shown that monozygotic (MZ) twin pairs have a significant higher concordance of MO than dizygotic twin pairs. The incomplete concordance among MZ twin pairs may be due to a lower genetic liability among discordant than concordant MZ twin pairs. The present study analysed the genetic liability in MZ twin pairs concordant and discordant for MO by the population‐relative risk of MO among parents and siblings. The twin pairs were from the population‐based Danish Twin Register. First‐degree relatives of 29 concordant and 34 discordant MZ twin pairs were blindly telephone interviewed by a physician. The participation rate of the eligible first‐degree relatives was 96%. The population‐relative risk of MO among parents and siblings was 2.73 (2.39–3.06) in concordant and 2.37 (2.03–2.71) in discordant MZ twin pairs. The relative risk of MO was significantly higher in female first‐degree relatives of concordant than of discordant MZ male and female twin pairs. An opposite effect was observed in male first‐degree relatives, although this was not significant for male first‐degree relatives of female MZ twin pairs. The present study found no statistically significant difference in genetic liability to MO among concordant and discordant MZ twin pairs. However, a difference in genetic liability among MZ and DZ twin pairs is anticipated to be small. Thus, it may be possible to show the effect in a larger study population or by investigating a more frequent trait than MO.