The existence of articular chondrocalcinosis was documented in 9 members of 3 generations of a Quebec family. No associated or secondary forms of the disease were found. The clinical manifestations appeared early in life, and extensive radiologic involvement was apparent. We determined that genetic transmission was dominant, either autosomal or sex-linked, and not related to the HLA system.Familial articular chondrocalcinosis was first reported in Czechoslovakia in 1957 by Sitaj and Zitnan (1). Since then, other families have been described in Chile (2), Holland (3), France (4), and the United States (5). In these reports from various countries, there seem to be variations in the type and severity of the clinical manifestations of the disease, as well as in the mode of genetic transmission.The purpose of our study was to establish and document the existence of this disease in three generations of a family from Quebec and to eliminate from the study secondary or associated forms of the disease. We also wanted to characterize the mode of genetic trans- 26, 1980. mission in our series through genealogic studies and HLA typing. PATIENTS AND METHODSThe discovery of articular chondrocalcinosis in 2 sisters prompted a clinical study of this family. Data were collected on both living and dead members of the family, and the family pedigree was defined through research in medical, municipal, and parochial archives. All living members of the family were requested to complete questionnaires and submit to physical examinations.Complete radiologic articular series were done on all symptomatic subjects. In nonsymptomatic members, roentgenograms of the hands, wrists, knees, and pelvis were performed. The radiologic degenerative changes were graded according to a modified version of the criteria of Kellgren (6).All affected living members and 7 unaffected subjects had determinations of blood calcium, inorganic phosphates, alkaline phosphatase, glucose, uric acid, iron, transferrin (7), copper (8), and ceruloplasmin (9).Laboratory studies in symptomatic individuals included: complete blood count, rheumatoid factor test, VDRL, complete urinalysis, 24-hour determination of urinary calcium, and determination of the level of parathyroid hormone (10). T h e urine was also assessed for the presence of homogentisic acid.When possible, HLA typing was done by a modified version of the method of Terasaki ( I 1). The lymphocytes were separated by using a gradient of density by the Ficoll-Hypaque technique (12). The lymphocytes were tested with antisera of 39 specificities: 18 of the A locus-I, 2, 3, 9, 10, I I , w23, w24, 25, 26, 28, 29, w30, w31, w32, w33, w34, w36; and 21 of the B locus-5, 7, 8, 13, 14, 15, 17, 18, w22, 27, w35, w38, w39, 40, w42, w44, w45, w49, w50, w51, w52. Fluid from the knees of 3 individuals was aspirated. A synovianalysis was performed, and a polarized microscopic study was done to determine the existence of calcium pyrophosphate dihydrate crystals (CPPD) (13).For all deceased members of the family, we at...