LCT encodes lactase, a glycosidase enzyme located in the intestinal brush border membrane that catalyzes the hydrolysis of lactose into D-glucose and D-galactose 1234. The mature protein contains two functional domains with broad glycosidase activity: one preferentially hydrolyzes hydrophilic substrates like lactose and cellobiose, while the other targets hydrophobic substrates including phlorizin and glycosylceramides 134. Lactase persistence (the ability to digest lactose in adulthood) is controlled by regulatory polymorphisms in the LCT gene. The European C/T-13910 polymorphism and African variants (G/C-14010, T/G-13915, C/G-13907) represent convergent evolution under strong selective pressure from dairy consumption, with evidence of selective sweeps over approximately 7,000 years 5. Clinically, homozygous recessive genotypes (CC at position -13910) are associated with primary lactose intolerance in children over 6 years old 6. This condition leads to reduced dairy consumption and is associated with lower serum vitamin D and calcium levels, potentially increasing deficiency risk 7. The gene is also associated with congenital lactase deficiency, a rare inherited disorder affecting lactose digestion from birth.