Allergic Rhinitis and Chronic Migraine: A Four-Generation Family Case Study in Al Bayda City, Libya

Epidemiological data frequently show a co-occurrence between allergic rhinitis (AR) and migraine; However, the exact genetic mechanisms driving this persistent comorbidity and whether it segregates as a linked hereditary trait within multi-generational families remain poorly understood. This study investigates the phenotypic correlation and genetic transmission patterns of comorbid AR and chronic migraine within a multi-generational lineage in Al Bayda, Libya. This involved a full family case study with screening of 54 members across 4 successive generations. For phenotype analysis, ARIA criteria were used for AR and ID-Migraine™, ICHD-3, HIT-6, and MIDAS tools for migraine-induced disability. Various statistical tests such as Chi-square test, Fisher’s Exact test, and Spearman rank correlation were done through IBM SPSS. A complete phenotypic overlap was observed, whereby all 32 patients affected with AR were also affected by chronic migraines (n=32, 59.3%), whereas all the other individuals that were not affected by either disorders were free of both illnesses (χ² = 45.2, p<0.001). Correlation analysis by the Spearman method showed a strong, positive correlation between AR and headache disability index HIT-6 (rs=0.78, p<0.001) and MIDAS (rs=0.72, p<0.001). The pedigree analysis established that there is no break in vertical transmission through four generations of equal sex ratio (F=16, M=16, p=0.742). Definitive male-to-male transmission was confirmed from branches G3-7 to G4-18 and 19, with an overall estimated trait penetrance of 59.3%.

Conclusion: The segregation of the comorbid (AR + Migraine) trait across this lineage strictly follows an autosomal dominant pattern of inheritance with high penetrance. While these disorders are typically considered polygenic in the general population, the structural clarity of this pedigree strongly implies a single-gene pleiotropic effect or a high-effect master variant segregating within this geographical cohort, driving both mucosal inflammation and trigeminal sensitization.