THE COMORBID ASSOCIATION OF MIGRAINE WITH OSTEOARTHRITIS AND HYPERTENSION - COMPLEMENT C3F AND BERKSONS BIAS

Migraine is known to have a major genetic component and has been assoc iated with a wide variety of comorbid disorders including arthritis an d heart disease. Since migraine and some of its comorbid disorders inv olve inflammation, complement C3, a protein involved in acute inflamma tion, was selected for analysis as a candidate gene in an ongoing stud y of the genetic basis of migraine. Polymorphism frequencies for compl ement C3F (0.19) and C3S (0.81) in a sample of 137 unrelated migraineu rs were found to be consistent with a control group as well as previou s population studies, indicating that this common polymorphism has no association with migraine susceptibility. However, C3F positive indivi duals with migraine were found to have an increased incidence of osteo arthritis (Chi square=10.06; p<0.0008) and hypertension (Chi square=5. 18; p<0.01). Therefore, the data in the present study indicate that ce rtain migraine comorbidities that have been reported in the literature may result from Berkson's bias as opposed to a shared pathophysiologi cal variation in the C3 gene.