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1. slow movement away from the normal or original position.
2. a chance variation, as in gene frequency from one generation to another; the smaller the population, the greater are the random variations.
antigenic drift relatively minor changes in the antigenic structure of a virus strain, probably resulting from natural selection of variants circulating among an immune or partially immune population. See also antigenic shift.
ulnar drift ulnar deviation.
A joint abnormality at the metacarpophalangeal joints, resulting from chronic synovitis, and frequently seen in rheumatoid arthritis. In this condition, the long axis of the fingers deviates in an ulnar direction with respect to the metacarpals.
See also: drift