Is LCT useful for allergy?

LCT (lactase persistence) is not useful for allergy. The LCT gene determines the ability to digest lactose (milk sugar). Lactose intolerance is a digestive disorder, not an allergy. A true milk allergy involves an immune reaction to milk proteins (e.g., casein, whey). LCT testing cannot predict or diagnose allergies. Evidence: strong for lactose intolerance, but not applicable to allergies. Caveat: confusion between lactose intolerance and milk allergy is common; medical evaluation (skin prick test, IgE) is required for suspected allergy.