- Human cholesterol 7alpha-hydroxylase (CYP7A1) deficiency has a hypercholesterolemic phenotype. Pullinger, C.R., Eng, C., Salen, G., Shefer, S., Batta, A.K., Erickson, S.K., Verhagen, A., Rivera, C.R., Mulvihill, S.J., Malloy, M.J., Kane, J.P. J. Clin. Invest. (2002)