MTNR1B and gestational diabetes: Our previous candidate gene association studies have also confirmed that angiotensin-converting enzyme 2 (ACE-2), retinoic acid X receptor-γ (RXR-γ), CDK5 regulatory subunit-associated protein 1-like 1 (CDKAL1), melatonin receptor 1 B (MTNR1B), and transcription factor 7 analog-2 (TCF7L2), which either affect GDM risk or are significantly associated with genetic susceptibility to GDM through interactions with age, pre-BMI, and blood lipids (12–15).