Histologic evaluation of distal colons of ApcMin/+ NHE3−/− mice revealed a predominance of adenomas with high-grade dysplasia (characterized by pronounced nuclear atypia, loss of epithelial cell nuclear polarity, mucosal gland cribriform appearance), with fewer lesions characterized as adenomas with low-grade dysplasia (characterized by elongated and crowded crypt cells with hyperchromatic nuclei that maintain polarity with respect to the basement membrane) or intraepithelial neoplasia (carcinoma in situ) defined as dyplastic crypt foci < 0.5 mm diameter32. The gene discussed is SLC9A3; the disease is intraepithelial neoplasia.