Chondrocalcinosis, or cartilage calcification, is a common condition that usually results from deposition of crystals of calcium pyrophosphate dihydrate (CPPD) in articular hyaline and fibro-cartilage. CPPD crystal deposition may be asymptomatic or associated with characteristic acute attacks ('pseudogout') or chronic arthritis. It can be detected radiographically. Chondrocalcinosis occurs in 3 forms: a primary hereditary form (e.g., CCAL2); a form associated with metabolic disorders (e.g., hyperparathyroidism, hemochromatosis, and hypomagnesemia); and a sporadic form, which may in some cases represent the hereditary form (summary by Hughes et al., 1995 and Richette et al., 2009). Genetic Heterogeneity of Chondrocalcinosis Another form of chondrocalcinosis (CCAL1; 600668) has been mapped to chromosome 8q.