[Major OLA histocompatibility complex of sheep. Frequency of factors in sheep affected by trembling (scrapie) or normal sheep]. / Le complexe majeur d'histocompatibilité OLA du mouton. Fréquence des facteurs chez des Ovins atteints ou non de tremblante (scrapie).

The OLA histocompatibility complex of sheep was studied in a flock of Ile-de France breed affected with Scrapie. On the whole, gene frequencies of 9 out of 11 factors were increased in the non-affected sheep of this contaminated flock. In these sheep, frequencies of the three following genes appeared to be increased significantly: OLA-A4, OLA-A8, OLA-B6. When these genes were present in the sheep of this flock, the relative risk of Scrapie was estimated at 0.05, 0.10 and 0.25, respectively.