Lct, or lactase, is an enzyme crucial for lactose digestion in the small intestine. It breaks down lactose into glucose and galactose, facilitating nutrient absorption. Its activity is associated with the LCT-13910C>T polymorphism 13910 bp upstream of the LCT-encoding gene [1,2,3].

Primary lactose intolerance (PLI), a decrease in lactase activity often seen from 1-5 years old, is related to single-nucleotide polymorphisms of the LCT gene. In children over 6 years old, the 13910CC and 22018GG LCT polymorphisms are significantly correlated with positive hydrogen breath test results, suggesting a potential for diagnosing lactose intolerance [1]. In the Italian and Turkish populations, the LCT-13910C>T polymorphism was not associated with an increased risk of colorectal cancer or polyps [2,3]. In the Armenian population, the lactase persistence allele LCT-13910T has a very low frequency (2.7%), supporting phenotypic data on lactose malabsorption there [4].

In conclusion, Lct is essential for lactose digestion. Genetic studies on Lct, especially those focusing on its polymorphisms, have provided insights into lactose intolerance and its potential relationship with colorectal cancer. These findings contribute to our understanding of digestive-related diseases and the genetic basis of lactose metabolism.