Genotype and phenotype correlations in congenital glaucoma

Purpose: To determine whether there is a correlation among mutations in the cytochrome P450 1B1 gene (CYP1B1), the degree of angle dysgenesis observed histologically, and disease severity in congenital glaucoma. Methods: Direct DNA sequencing was utilized to screen six unrelated children with congenital glaucoma, each set of parents, and all siblings for CYP1B1 mutations. Specimens of the anterior chamber angle obtained at trabeculectomy were examined histologically to identify abnormalities of the aqueous outflow pathway. CYP1B1 mutations were correlated with both the degree of angle dysgenesis and the patient's disease severity (age at diagnosis, difficulty in achieving intraocular pressure control). Results: Four of the six patients (66.7%) were compound heterozygotes for mutations in the CYP1B1 gene. Seven of the eight CYP1B1 mutations were identified, including two novel mutations (R117P, C209R) and five others previously described (G61E, R368H, R390H, E229K, 4340delG). The cases were divided based on histological phenotype into categories of (1) severe goniodysgenesis highlighted by the agenesis of Schlemm's canal (two patients), (2) moderate goniodysgenesis characterized by the presence of a band of collagenous tissue in the trabecular meshwork and/or the juxtacanalicular tissues (three patients), and (3) mild goniodysgenesis with deposition of a mucopolysaccharide material in the juxtacanalicular tissue (one patient). CYP1B1 mutations were identified in both cases of severe angle dysgenesis and two of three cases of moderate dysgenesis. Disease severity closely correlated with the degree of angle dysgenesis. Conclusion: The majority of cases in the cohort had compound heterozygous CYP1B1 mutations. Specific CYP1B1 mutations may be associated with severe or moderate angle abnormalities.