However, when each special type was separately analyzed, ERBB2-low was less often found in mucin-producing carcinomas (pure mucinous or mixed with micropapillary) vs nonmucinous tumors (15 of 39 patients [38.5%] vs 1244 of 2161 patients [57.6%]; P = .02). The gene discussed is MUC5AC; the disease is carcinoma.