Lymph node CD4+ T cell expression data from nave female offspring of C57BL/6J and C57BL/6J-ChrY^SJL

The prevalence of some autoimmune diseases (AID) is greater in females compared with males, notwithstanding that disease severity is often greater in males. The reason for this sexual dimorphism (SD) is unknown, but may reflect negative selection of Y chromosome (ChrY) bearing sperm during spermatogenesis or male fetuses early in the course of conception/pregnancy. Previously, we showed that the SD in experimental autoimmune encephalomyelitis (EAE) is associated with copy number variation (CNV) in ChrY multicopy genes. Here, we test the hypothesis that CNV in ChrY multicopy genes influences the paternal parent-of-origin effect on EAE susceptibility in female mice. We show that C57BL/6J consomic strains of mice possessing an identical ChrX and CNV in ChrY multicopy genes exhibit a female biased sex-ratio and sperm head abnormalities, consistent with X-Y intragenomic conflict arising from an imbalance in CNV between homologous ChrX:ChrY multicopy genes. These males also display paternal transmission of EAE to female offspring and differential loading of miRNAs within the sperm nucleus. These findings provide evidence for a genetic mechanism at the level of the male gamete that contributes to the SD in EAE and paternal parent-of-origin effects in female mice, raising the possibility that a similar mechanism may contribute to the SD in MS.

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Case LK, Wall EH, Osmanski EE, Dragon JA, Saligrama N, Zachary JF, Lemos B, Blankenhorn EP, Teuscher C