[HLA-A29 sub-types and "Birdshot" choroido-retinopathy susceptibility: a possible "resistance motif" in the HLA-A29.1 molecule].
The Birdshot choroidoretinopathy (BSCR) is an ocular disease strongly associated with HLA-A29. The HLA-A29 specificity can be split using immunoelectrofocusing in two subtypes A29.1 and A29.2. BSCR susceptibility is exclusively linked to the HLA-A29.2 molecule. The sequence of HLA-A29.2 was established (EMBL X60108 and found to be identical between patients and healthy individuals. A single difference was found (H----D) 102) in the extra cellular domains between HLA-A29.2 and HLA-A29.1. The HLA-A29 sub-types shares the consensus HLA class I sequence (D102). The mutation exhibited by HLA-A29.1 (H102) is unique to that molecule. The ancestral type is thus HLA-A29.2 that confers the susceptibility to BSCR whereas HLA-A29.1 has arisen from a more recent mutation conferring resistance to BSCR. Another single amino-acid difference between HLA-A29.1 and HLA-A29.2 was found in the intracytoplasmic part of the molecule, HLA-A29.2 exhibiting the HLA-A consensus sequence whereas A29.1 shares with AW33.1 the mutation S----F321. In addition, the A29 specificity was assigned to L and Q amino-acids at position 62-63, which can interact with peptides into the binding groove. No specific T or B epitope of susceptibility could be considered involving the region of the mutation discriminating HLA-A29.2 from HLA-A29.1. The HLA-A29.1 mutation is unable to interact with the T cell receptor and did not seem to induce significant structural changes in the peptide-binding groove. Conversely, its position suggests that the A29.1 mutation might interfere with the binding of an accessory molecule, the CD8 molecule being the most likely candidate for that role.
Tabary
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Laboratoire d'Immunologie, Hôpital Robert-Debré, Reims.
Prochnicka-Chalufour
A
A
Cornillet
P
P
Lehoang
P
P
Betuel
H
H
Cohen
J H
JH
D000595:Amino Acid Sequence; D001483:Base Sequence; D002825:Chorioretinitis / Q000276:immunology*; D004252:DNA Mutational Analysis; D005091:Exons; D015234:HLA-A Antigens / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D007525:Isoelectric Focusing; D008969:Molecular Sequence Data
D015234:HLA-A Antigens
Sous-types HLA-A29 et susceptibilité à la choroïdorétinopathie de type "Birdshot": un "motif de résistance" possible dans la molécule HLA-A29.1.