COPB2 and mitochondrial disease: The head-to-tail overlapping genes MRPS22 and COPB2 are located nearest to rs1873668 and rs4243399, whereas rs16849083 is located in the intronic region of PBP2. Mutations in MRPS22, a mitochondrial ribosomal protein, lead to antenatal mitochondrial disease, which presents with antenatal skin edema, hypotonia, cardiomyopathy, and tubulopathy [18].