Inheritance of open-angle glaucoma in the Barbados family study

The majority of genetic studies on open-angle glaucoma (OAG) have been conducted in primarily white populations, with investigations of inheritance patterns largely based on self-reported information. The Barbados Family Study of Open-Angle Glaucoma (BFSG) is the first study to investigate the transmission pattern(s) for OAG in a predominantly black population, based on standardized examinations. Each BFSG participant received a comprehensive examination including anthropometric and other measurements, best-corrected visual acuity, perimetry, tonometry, lens gradings, fundus photography, venipuncture, an extensive interview including ocular, medical and family history information and a comprehensive ophthalmologic evaluation. Conservative criteria were used to define glaucoma status, including the presence of both visual field defects and optic disc damage. The study included 207 OAG-affected probands (median age: 68 years) and 1,056 of their relatives (median age: 47 years). Among the relatives examined 10% (n = 106) had OAG and 13% (n = 141) had probable OAG. Segregation analyses were performed to determine the mode of inheritance for glaucoma in these families. The results indicate that transmission of OAG or probable OAG is most likely due to a major codominant gene. Both age and gender are shown to be significant factors as well; with an increase in risk being associated with each year of age over 54 years and an increase in risk for all ages and genotypes observed in males. These analyses do not, however, preclude the possible existence of an environmental component or other genetic determinants in OAG. Further evidence for the existence of a major gene may be obtained by additional follow-up of the relatively young cohort of relatives, as well as ongoing linkage analyses.