The strong association of specific haplotypes with some predominant CYP1B1 mutations underlying PCG and the observed geographical clustering, probably due to founder effects, may be useful for predictive testing.
Sequence analysis and homology modeling suggest that primary congenital glaucoma on 2p21 results from mutations disrupting either the hinge region or the conserved core structures of cytochrome P4501B1.
The molecular basis of PCG in two families was determined: two novel mutations (a deletion and a point mutation) and one novel polymorphism in CYP1B1 were identified in addition to a previously described single amino acid substitution.
Three distinct levels interact sequentially to produce PCG: (i) genetic mutations mainly affecting the CYP1B1 gene, (ii) absence or dysregulation of a morphogen, and (iii) trabecular meshwork pathological changes either in patterning or remodeling.
On screening these patients for mutations in myocilin (MYOC), another glaucoma-associated gene, using denaturing high-performance liquid chromatography followed by sequencing, we identified a patient who was double heterozygous at CYP1B1 (c.1103G>A; Arg368His) and MYOC (c.144G>T; Gln48His) loci, suggesting a digenic mode of inheritance of PCG.
We present a comprehensive sequence analysis of the translated regions of the CYP1B1 gene in 22 PCG families and 100 randomly selected normal individuals.
These results confirm the pathogenicity of the analysed missense CYP1B1 variants and further support the concept that either absent or very low CYP1B1 activity levels are the primary molecular defect involved in PCG pathogenesis.
Our results suggest primary congenital glaucoma and the anterior segment dysgenesis disorders may share a common molecular pathophysiology in the CYP1B1 pathway.