The advent of the discipline of molecular genetics over the past decade has led to a dramatic growth in our understanding of the genetics of a myriad of diseases. Ophthalmology has benefited greatly from this new technology, with significant advances in our knowledge about conditions as varied as aniridia and retinitis pigmentosa.1 2 Our understanding of the genetics of primary open angle glaucoma (POAG) may not be as clear as with some other ophthalmic conditions but, nevertheless, there have been great advances since the last review about the genetics of glaucoma published in the BJO in 1980.3 At that time, our knowledge was based on a number of conflicting studies attempting to link human polymorphisms, such as the ability to taste phenyl thiocarbamide, with glaucoma.4 Nowadays, the positions of genes responsible for various forms of glaucoma have been localised, not just to individual chromosomes, but to specific small regions on those chromosomes. Recently, for the first time, a gene responsible for a specific form of POAG has been identified. This review aims to highlight and explain the important recent advances in our understanding of the genetics of POAG. Primary open angle glaucoma, for the purpose of this review, refers to those cases of glaucoma in which there is not only no evident antecedent or related ocular disease but also the angle of the anterior chamber remains open at all times.5 The possibility of a genetic predisposition to glaucoma was first realised in 1842 when Benedict reported the occurrence of glaucoma in two sisters.6 Despite the intervening 150 years, our understanding of the genetics of POAG remains unclear. Certainly, most POAG pedigrees do not show a simple Mendelian pattern of inheritance. However, relatives of patients with glaucoma do run an increased risk of developing the condition …