title: Assessing risk factors for migraine: differences in gender transmission.
abstract: OBJECTIVE
  Our aim was to assess which specific factors are contributing to an increased risk of migraine in a group of 131 Portuguese families.
  
  
  METHODS
  We studied 319 first-degree relatives, using a multilevel approach to account for the dependency among members from the same family. We included in the model relative's gender, the proband's gender and age-at-onset, to evaluate if any of these variables were associated with relative's affection status. We also included in the model proband's migraine subtype. We further assessed female and male transmissions within the proband nuclear family.
  
  
  RESULTS
  Relatives' gender was found to be a risk factor for migraine (Odds Ratio = 2.86; 95% CI = 1.75-4.67), with females at a higher risk. When splitting probands according to their migraine subtype, we found that none of the variables studied contributed to relatives of MA-probands affection-status. Our results also show a significant difference between proband's transmission and the gender of the parents and offspring.
  
  
  CONCLUSIONS
  With this study, we showed that gender is truly a risk factor for migraine and that a gender-biased transmission is also observed. This reinforce the importance of identifying genes associated with migraine that are modulated by genes located in the sex chromosomes and the study of mitochondrial DNA or X-chromosome and hormonal-related effects associated with migraine susceptibility.
authors.affiliation: UnIGENe, Instituto Biologia Molecular Celular, Universidade do Porto, Porto, Portugal. clclemos@ibmc.up.pt
authors.forename: Carolina
authors.initials: C
authors.lastname: Lemos
authors.forename: Isabel
authors.initials: I
authors.lastname: Alonso
authors.forename: José
authors.initials: J
authors.lastname: Barros
authors.forename: Jorge
authors.initials: J
authors.lastname: Sequeiros
authors.forename: José
authors.initials: J
authors.lastname: Pereira-Monteiro
authors.forename: Denisa
authors.initials: D
authors.lastname: Mendonça
authors.forename: Alda
authors.initials: A
authors.lastname: Sousa
mesh_terms: D000328:Adult; D017668:Age of Onset; D005190:Family; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D040582:Inheritance Patterns; D008297:Male; D008875:Middle Aged; D008881:Migraine Disorders / Q000453:epidemiology* / Q000235:genetics*; D016017:Odds Ratio; D010375:Pedigree; D011174:Portugal / Q000453:epidemiology; D012307:Risk Factors; D012737:Sex Factors