Rheumatoid factors in families.

Ziff, Schmid, Lewis, and Tanner (1958) first reported that rheumatoid factors reacting with human Cohn fraction II gamma globulins assessed by means of a latex-fixation test (LEI) were aggregated in the families of hospital patients with rheumatoid arthritis. This evidence for familial aggregation was confirmed by Ball and Lawrence (1961) in the urban population sample of Leigh, England, the test system being a sheep cell agglutination test (SCAT) for rheumatoid factor reacting with rabbit gamma globulin. It was further shown that in these sera there was a graded relationship between the titre in the probands and in the relatives. Somewhat unexpectedly, most of the aggregation occurred in the offspring (Lawrence, 1963). Bennett and Burch (1968 a, b) found significant aggregation of rheumatoid factor reacting with human gamma globulin (BFE) by sib-pair analysis in Pima but not in Blackfeet Indians, but showed that the aggregation was related to sibship size and therefore considered it was not genetically determined. Fudenberg and Franklin (1965) observed families in which there appeared to be a genetically-determined basis for both the rheumatoid factor and the reactant 7S gamma globulin. In view of these conflicting results and the continuing uncertainty as to the significance of familial aggregation, we have made a survey of the firstdegree relatives and spouses of persons with positive tests for rheumatoid factor in a rural population sample in Wensleydale in the north of England.