“…In the sero-negative families, both the minimal and severe forms of arthritis occurred with about the expected frequency. Differences between sero-positive and seronegative families have been reported also by Wilkinson and Torrance (1967), de Blecourt, Boerma, and Vorenkamp (1962), and Bland and Brown (1963) 3-6** Sero-negative rheumatoid arthritis 300 12 10-1 1-2 4 3-3 1-2 ** P = 0-01…”