Genetic Factors in Generalized Osteo-Arthrosis

Abstract

The first-degree relatives of twenty males and 32 females with definite osteo- arthrosis in six or more groups of joints, a total of 84 male and 97 female relatives, have been examined clinically, radiologically, and by means of the sheep cell agglutination test (S.C.A.T.) and the test for serum cholesterol, and have been compared with a random sample of the population examined in the same way and at the same time. 45 of the male and 55 of the female relatives were aged 45 and over and, unless otherwise stated, the following refers to this part of the sample. Definite multiple osteo-arthrosis with 5 or more groups of joints involved (MDA) was found in 36% of the male relatives, 17% expected, and in 49% of the female relatives, 26% expected. When the relatives were divided into two groups according to the presence or absence of Heberden''s nodes in the proband, definite MDA was equally prevalent in both groups, but a distinctly higher prevalence of severe MDA (Grade 3 and 4 in at least three groups of joints) occurred in the relatives of the "nodal" probands. Clinically-observed Heberden''s nodes of moderate or severe grade were found in 45% of female relatives of "nodal" probands (only 10% expected), and in 13% of female relatives of "non-nodal" probands (10% expected). Clinical inflammatory polyarthritis was present in 38% of female relatives of "non-nodal" probands but in only 10% of female relatives of "nodal" probands, the expected rates being 8 and 10% respectively. Radiological evidence of erosive arthritis was difficult to assess in this sample, but appeared to be more frequent in the female relatives of non-nodal probands. Morning stiffness also showed a slight increase over the expected rates in this sub-group. The results of the S.C.A.T. showed no appreciable difference from the expected rates in any group of relatives. Serum cholesterol showed at least moderate deviations from the appropriate population mean in 58% of the male relatives under 45 years of age (23% expected), and in 52% of male relatives, irrespective of age, belonging to "non-nodal" probands (27% expected). In view of the many factors influencing the level of serum cholesterol, no conclusions are drawn from these findings. Spouses showed no increase in MDA over the expected rates. It is concluded that more than one common inherited factor may give rise to MDA. The more severe forms appear to be more closely associated with Heberden''s nodes, the others with inflammatory-preponderantly sero-negative-polyarthritis.