UQCRB and spontaneous abortion: Similarly, Lyu et al. previously reported downregulation in gene expression associated with oxidative phosphorylation in the placental villi and showed the involvement of UQCRB, a subunit of mitochondrial complex III, A and the TP5G1 and ATPG3 genes in the impairment of mitochondrial respiratory chain function in the placental villi was a contributor to miscarriage [38].