Consequently, Il11ra−/− female mice fail to support proper embryonal implantation and are therefore infertile.25 Consistent with impaired but not fully blunted IL-11 signaling, we observed a slight reduction in litter size in our GP130 p.R279Q mice, when female mice carried at least one mutant Il6st allele. The gene discussed is IL6ST; the disease is Infertility.