Purpose: To report the association of HLA antigens with keratoconus in Japanese patients.
Design: Observational consecutive case series.
Methods: In 90 consecutive Japanese keratoconus patients, HLA class I (HLA-A, -B, -C) and class II (HLA-DR, -DQ) were analyzed.
Results: Compared with control frequencies, based on mean gene frequencies for the Japanese population, higher frequencies of HLA-A26, B40, and DR9 antigens were found in patients whose conditions were diagnosed before 20 years of age (chi(2) = 6.45, P =.01; chi(2) = 6.78, P =.01; chi(2) =3.99, P =.05, respectively), but were not found in patients whose conditions were diagnosed later in life. Men were significantly younger at diagnosis than were women. No obvious relation was found between HLA antigens and other clinical data.
Conclusion: HLA-A26, B40, and DR9, which were found relatively frequently in the ancient Japanese population, seem to be associated with keratoconus in younger individuals.