SEQUENCE-ANALYSIS AND HOMOLOGY MODELING SUGGEST THAT PRIMARY CONGENITAL GLAUCOMA ON 2P21 RESULTS FROM MUTATIONS DISRUPTING EITHER THE HINGEREGION OR THE CONSERVED CORE STRUCTURES OF CYTOCHROME P4501B1

We recently reported three truncating mutations of the cytochrome P450 1B1 gene (CYP1B1) in five families with primary congenital glaucoma (P CG) linked to the GLC3A locus on chromosome 2p21. This could be the fi rst direct evidence supporting the hypothesis that members of the cyto chrome P450 superfamily may control the processes of growth and differ entiation. We present a comprehensive sequence analysis of the transla ted regions of the CYP1B1 gene in 22 PCG families and 100 randomly sel ected normal individuals. Sixteen mutations and six polymorphisms were identified, illustrating an extensive allelic heterogeneity. The posi tions affected by these changes were evaluated by building a three-dim ensional homology model of the conserved C-terminal half of CYP1B1. Th ese mutations may interfere with heme incorporation, by affecting the hinge region and/or the conserved core structures (CCS) that determine the proper folding and heme-binding ability of P450 molecules. In con trast, all polymorphic sites were poorly conserved and located outside the CCS. Northern hybridization analysis showed strong expression of CYP1B1. in the anterior uveal tract, which is involved in secretion of the aqueous humor and in regulation of outflow facility, processes th at could contribute to the elevated intraocular pressure characteristi c of PCG.