Molecular genetic studies conducted during the last several years have thrown some light on the basic molecular defects in primary congenital glaucoma (PCG) and the rationale behind the clinical and genetic presentation of this paediatric eye condition. The existence of a hereditary form of PCG segregating as an autosomal recessive trait with high penetrance is now confirmed. The primary molecular defect underlying the majority of PCG cases has been identified as mutations in the cytochrome P4501B1 (CYP1B1) gene. This gene is expressed in tissues of the anterior chamber angle of the eye. Molecular modelling experiments suggest that mutations observed in PCG patients interfere with the integrity of the CYP1B1 molecule as well as its ability to adopt a normal conformation and bind haem. On the basis of these observations, we hypothesised that CYP1B1 participates in the normal development and function of the eye by metabolising essential molecules that are perhaps used in a signalling pathway. Revealing the identity of this molecule is our major objective since it can lead to as yet unknown biochemical cascades controlling the terminal stages of anterior chamber angle development.