MTNR1B and gestational diabetes: In European Caucasian populations, polymorphisms in genes such as CDK5 regulatory subunit-associated protein 1-like 1 (CDKAL1), cyclin-dependent kinase inhibitor 2A/2B (CDKN2A/2B), transcription factor 7-like 2 (TCF7L2), and melatonin receptor 1B (MTNR1B) have been implicated in the development of gestational diabetes [19].