Association between RS3763040 polymorphism of the AQP4 and idiopathic intracranial hypertension in a Spanish Caucasian population

BACKGROUND: Idiopathic intracranial hypertension (IIH) is a condition of increased intracranial pressure of unknown aetiology. Principal symptoms are headache, visual disturbances, and obesity, together with elevated intracranial pressure. Unspecified MRI, despite normal ventricle size, suggests alterations in the water flux cellular mediated by the brain water channel aquaporin-4 (AQP4). The association among IIH, cerebral spinal fluid malfunction, reabsorption, and functional or regulatory modifications of AQP4 is a hypothesis not confirmed. METHODS: Blood samples were collected from 72 Spanish Caucasian patients with IIH. A genetic association study was performed with bi-allelic SNPs rs1049305 and rs10244884 in AQ1 and rs2075575, rs3763043, and rs3763040 in AQ4. Genetic data were compared with 94 healthy Caucasian control. Statistics studies were assessed by Pearson’s χ (2) tests for 2 × 2 (alleles) or 3 × 2 (genotypes) contingency tables. A P value < 0.05 was considered to be statistically significant. RESULTS: Statistically significant differences were found when comparing the results of the rs3763040 polymorphism of the AQ4 locus of IIH patients with controls, in genotypic frequencies (P = 0.0442) and allele frequencies (P = 0.0171). Furthermore, a statistically significant difference (P = 0.0207) was found in individuals carrying and not carrying the minor allele (GG + GA individuals vs GG homozygotes). No statistically significant differences were found when comparing allele and genotypic frequencies for SNPs rs1049305 and rs10244884 of AQ1 and rs2075575 and rs3763043 of AQ4. CONCLUSIONS: The association of AQP4 and specifically of its polymorphic variant rs3763040 with IIH should be validated in other ethnic groups in order to assess more precisely the role of AQP4 in the etiopathogenesis of IIH.