Genetic study of late-onset neonatal sepsis reveals significant differences by sex

Late-Onset Neonatal Sepsis (LOS) is a rare, but life-threatening condition, involving widespread infection, immune disruption, organ dysfunction, and often death. Because exposure to pathogens is not 100% preventable, identifying susceptibility factors is critical to defining neonates at greater risk. Prior studies demonstrated that both genetics and infant sex influence susceptibility. We, therefore, performed a genome wide association study (GWAS) with 224 cases and 273 controls from six European countries to identify genetic risk factors. We tested for association with both autosomal and X-chromosome variants in the total sample and in the samples stratified by sex. In total 71 SNPs associated with neonatal sepsis at p<1x10-4 in at least one analysis. Most importantly, the sex stratified analyses revealed associations with multiple SNPs (28 SNPs in males and 16 in females), but none of 44 SNPs from single-sex analyses associated with sepsis in the other sex at p<0.05, and the vast majority showed significant SNP X sex interactions (17 of 28 from the male-only analyses and all 16 from the female-only study). Pathway analyses showed that NOTCH signaling is over-represented among loci identified by the analyses. Our results indicate that susceptibility to LOS is genetically sexually dimorphic, and suggest that NOTCH signaling is likely to play a role in it.