[B2] Measurement:Erythrocyte glutathione reductase assay is a better functional index of insufficient riboflavin intake (a coefficient >1.4 indicates riboflavin insufficiency).Symptoms of ariboflavonosis:Sore throat, hyperemia of pharyngeal mucous membranes, edema of mucous membranes, cheilitis, stomatitis, glossitis, normocytic-normochromic anemia, and seborrheic dermatitis. Here, GSR is linked to anemia (phenotype).