- The gene CYP3 encoding P450pcn1 (nifedipine oxidase) is tightly linked to the gene COL1A2 encoding collagen type 1 alpha on 7q21-q22.1. Brooks, B.A., McBride, O.W., Dolphin, C.T., Farrall, M., Scambler, P.J., Gonzalez, F.J., Idle, J.R. Am. J. Hum. Genet. (1988)