To investigate whether the corticotrophin-releasing hormone (CRH) genomic region confers genetic susceptibility to rheumatoid arthritis (RA) in the Spanish population.
DNA was obtained from 121 simplex RA families and 101 healthy controls, all from Spanish origin. Two microsatellites, CRHRA1 and CRHRA2, located 25 and 20 kb downstream respectively from the CRH gene were examined using a new multiplex design. Linkage disequilibrium (LD) between the markers was assessed and association studies were carried out using the transmission disequilibrium test (TDT) implemented in TRANSMIT.
Both markers are in Hardy-Weinberg equilibrium and there is significant LD between them in the Spanish population. Neither the polymorphic alleles of CRHRA1 and CRHRA2 markers nor their resulting haplotypes were significantly associated to RA. The associated haplotype in the UK population (CRHRA1*10; CRHRA2*14) was undertransmitted in RA patients (12 obs vs 17.43 exp), although the difference is not statistically significant (P > 0.05).
This is the first follow-up study of the association between the CRH genomic region and RA and suggests that the CRH gene may not be involved in the pathogenesis of RA in the Spanish population. Further studies in other populations will help untangle the real contribution of this genomic region to the susceptibility to RA.