Can a consumer DNA test interpret LCT reliably?

Consumer DNA tests can interpret the LCT gene (lactase) with reasonable reliability for individuals of European ancestry, because the primary SNP rs4988235 (C/T) in the MCM6 gene is strongly associated with lactase persistence (OR > 6). However, predictive accuracy drops for other ethnic groups, where different variants (e.g., rs41312345 in East Africa) are more relevant. The test indicates genetic predisposition, not a diagnosis. Lactose intolerance can also be secondary to gut diseases. Many companies overstate the power of a single SNP. Evidence for the specific variant in Europeans is human-strong, but global applicability is limited. A negative result does not rule out lactose intolerance, and a positive result does not guarantee symptoms. Clinical correlation (e.g., hydrogen breath test) remains the gold standard. Consumers should not base dietary changes solely on this result.