Lactose Intolerance, Celiac Disease, and IBD: The Genetics of Gut Health
The LCT gene determines lactose tolerance, HLA-DQ2/DQ8 rules out celiac disease, and NOD2 variants raise Crohn’s risk. Here’s what your DNA says about digestion.
Category: Research · By GenomeNarrator Team · · 6 min read
The relationship between genetics and gut health is one of the most practically useful areas of genomic medicine.
Lactose intolerance
The variant rs4988235, near the LCT gene, largely determines whether adults maintain the ability to digest lactose. The "persistence" allele (T) is common in Northern European ancestry populations; the "non-persistence" allele (C) is associated with reduced lactase activity in adulthood.
Celiac disease
Celiac has a strong HLA component. The HLA-DQ2 and HLA-DQ8 haplotypes are present in nearly all celiac patients, but also in about 30% of the general population, most of whom will never develop celiac. HLA testing is most useful as a rule-out: if you lack both haplotypes, celiac is extremely unlikely regardless of symptoms.
Fatty liver disease
The PNPLA3 variant rs738409 significantly modifies liver fat accumulation risk. Individuals with two copies of the risk allele have roughly 3x elevated risk of NAFLD, and this risk is amplified by obesity and alcohol consumption.
Inflammatory bowel disease
IBD has a complex polygenic architecture involving hundreds of variants. The NOD2 gene is one of the best-studied: certain variants increase Crohn's risk substantially, particularly in Ashkenazi Jewish populations.
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