Month of birth, HLA-DRB1*15 locus and risk of multiple sclerosis in offspring

A relationship among April births, HLA-DRB1*15:01 genotype and risk of multiple sclerosis (MS) has been described. We aim to determine this association in our cohort of Spanish MS patients.

We genotyped HLA-DRB1*15:01 allele in 326 MS patients and 226 controls (non-neurological disease patients) by SSP-PCR and compared month of birth with local births during the same period.

MS patients carrying HLA-DRB1*15 allele were more frequently born in December (10.3% HLA-DRB1*15+ vs. 3.8% HLA-DRB1*15-; p = 0.019). Controls carrying HLA-DRB1*15 allele were less frequently born in December than non-carrier controls (0% HLA-DRB1*15+ vs. 10.3% HLA-DRB1*15-; p = 0.028). Thus, December was confirmed as the common month of birth for HLA-DRB1*15-non-carrier controls and MS HLA-DRB1*15-carrier patients.

Month of birth, HLA-DRB1 genotype and risk of MS are associated. In Spain, this association was found in December, supporting the potential interaction of a seasonal risk factor in winter, inside/close to HLA-DRB1*15 locus, during pregnancy or after birth.