Blood groups as genetic markers in glaucoma

Abstract

A series of 474 mixed cases of glaucoma was assessed to determine whether there were any genetic differences between different types of glaucoma. A careful distinction was made between chronic open angle glaucoma (COAG), acute and chronic angle closure glaucoma, ocular hypertension, low tension glaucoma, patients with large cup disc ratios, and various types of secondary glaucoma including pseudoexfoliation of the lens capsule, uveitic and traumatic glaucoma. Using ABO blood groups, Rhesus groups, ABH secretion or non-secretion, and phenylthiourea tasting we identified certain differences. The differences from normal were significant decrease in Rh-negative patients in chronic closed angle glaucoma (p<0·05), a decrease in ABH secretors in ocular hypertension (p<0·01), and fewer HB secretors in patients with CO AG (p<0·02). There was a significant decrease in AH secretors and increase in HB secretors in both pseudoexfoliation with raised intraocular pressure compared with COAG (p<0·01) and in secondary glaucomas as a group compared with COAG (p<0·01). Tasters of phenylthiourea were more common in traumatic and uveitic glaucoma than in normal controls (p<0·05). These results suggest that secondary glaucoma develops in different subjects from COAG, while patients who develop a rise in intraocular pressure proceed to cupping and field loss if they have a certain genetic constitution. The groups of patients are too small for the differences to be of great prognostic value.