A population-based case-control study of isolated anophthalmia and microphthalmia.

The purpose of the study was to reveal the etiological factors in the origin of isolated an/microphthalmia. The dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-2002 containing 56 cases with isolated an/microphthalmia and 22,744 malformed controls with other non-ocular defects from the Hungarian Congenital Abnormality Registry, in addition of 56 matched control pairs and 37,837 population controls without defects from the National Birth Registry, was evaluated. Exposure data and family history were collected (i) prospectively by prenatal logbook and other medical records, (ii) retrospectively through a structured questionnaire filled-in by mothers, and (iii) information obtained by regional nurses at home visit of non-respondent mothers. The autosomal recessive origin of isolated an/microphthalmia was indicated in about 10% of cases on the basis of sib recurrence. Cases with isolated an/microphthalmia had a much shorter mean gestational age and smaller mean birth weight, a much larger proportion of preterm birth and low birthweight. Their mothers were younger with a predominance of first birth order, frequently unmarried with low socioeconomic status. These findings are in agreement with a much higher prevalence at birth of cases with isolated an/microphthalmia in the gypsy population probably due to the interaction of inbreeding effect and low socioeconomic status. Further molecular genetic studies are needed to identify gene mutations of isolated an/microphthalmia in the Hungarian gypsy population.