A population-based case-control study of isolated primary congenital glaucoma.

We studied the possible etiological factors of isolated primary congenital glaucoma (IPCG) using data from the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-2002. The study group consisted of 52 cases with IPCG compared to 52 matched control pairs without any defects, and 22,744 malformed controls with non-ocular defects and 37,837 population controls with no defect. Exposure data and family history were collected (i) prospectively by prenatal logbook and other medical records, (ii) retrospectively through a structured questionnaire completed by mothers, and (iii) from supplementary information obtained by regional nurses visiting the homes of non-respondent mothers. Autosomal recessive inheritance of IPCG was suspected on the basis of sib occurrence and parental consanguinity in 15% of cases. The shorter gestational age (with high proportion of preterm birth), higher birth order, large proportion of births among unmarried women, low socioeconomic status, and high rate of unemployment may be related to Gypsy origin of at least 54% of cases of IPCG. We conclude that the higher incidence of IPCG in the Hungarian Gypsy population is associated with their inbreeding and the possible founder effect of a gene mutation.