Initial screening is based on symptoms and blood tests to detect the levels of several antibodies that arise during an aberrant immune response to gluten. Other laboratory tests identify other abnormalities including altered liver enzymes and low cholesterol. Diagnosis is confirmed by a biopsy from the small intestine to identify the damage and by genetic screening to identify the celiac disease at-risk alleles (HLA-DQA1*05, HLA-DQB1*02 and HLA-DQB1*03:02). Nearly 100% of celiac-affected individuals carry one or more of these alleles.