MICA gene polymorphisms and HLA-B27 subtypes in Japanese patients with HLA-B27-associated acute anterior uveitis.
OBJECTIVE
HLA-B27-associated acute anterior uveitis (HLA-B27 AAU) seems to be triggered by external factors in persons with a particular genetic background. It is still uncertain whether HLA-B27 or other gene(s) near the HLA-B region predisposes to uveitis in a linkage disequilibrium with B27. The authors investigated microsatellite polymorphism within the transmembrane region of the MICA gene, located 47 kb centromeric of the HLA-B gene, and HLA-B27 subtypes.


METHODS
Seventeen HLA-B27-positive Japanese patients with HLA-B27 AAU, 51 Japanese controls, and 20 B27-positive Japanese controls were examined for MICA gene polymorphism within the transmembrane region using polymerase chain reaction (PCR) and subsequent automated fragment detection by fluorescent-based technology. Furthermore, B27-positive patients with HLA-B27 AAU and B27-positive controls were examined for HLA-B27 subtypes by the PCR-sequence-specific primer method.


RESULTS
The microsatellite allele in the MICA gene, consisting of four repetitions of GCT/AGC (designated A4 allele), was present at a significantly higher phenotype frequency in the patient group (64.7%) than in the control group (25.5%) (chi 2 = 6.95, Pc = 0.042). Furthermore, the frequency of the A4 allele was significantly higher, even when compared with 20% in the B27-positive control group (chi 2 = 5.88, Pc = 0.042). The frequency of HLA-B27 subtypes was not significantly different between B27-positive patients with HLA-B27 AAU and B27-positive controls.


CONCLUSIONS
These results suggest that the MICA gene itself, or other nearby gene(s), linked to the MICA A4 allele may be involved in the development of HLA-B27 AAU and that HLA-B27 subtypes are not important in the development of HLA-B27 AAU in a Japanese population.
Goto
K
K
Department of Ophthalmology, Yokohama City University School of Medicine, Japan.
Ota
M
M
Ando
H
H
Mizuki
N
N
Nakamura
S
S
Inoue
K
K
Yabuki
K
K
Kotake
S
S
Katsuyama
Y
Y
Kimura
M
M
Inoko
H
H
Ohno
S
S
D000208:Acute Disease; D000328:Adult; D000483:Alleles; D017931:DNA Primers / Q000737:chemistry; D004276:DNA, Satellite / Q000032:analysis; D004587:Electrophoresis, Agar Gel; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D015796:HLA-B27 Antigen / Q000235:genetics*; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D014606:Uveitis, Anterior / Q000235:genetics*
D017931:DNA Primers; D004276:DNA, Satellite; D015796:HLA-B27 Antigen; D015395:Histocompatibility Antigens Class I; C099187:MHC class I-related chain A