Uncoupling protein 2 (Ucp2) is reduced in cases of impaired ovulation associated with fetal exposure to hypothyroidism and mediates apoptosis, gap junction integrity, and progesterone synthesis in cumulus cells (Ge et al., 2017; Meng et al., 2016; Rousset et al., 2003). The gene discussed is UCP2; the disease is hypothyroidism.