FAMILIAL CHONDROCALCINOSIS DUE TO CALCIUM PYROPHOSPHATE DIHYDRATE CRYSTAL DEPOSITION IN ENGLISH FAMILIES

Abstract

Familial predisposition to chondrocalcinosis (CC) due to calcium pyrophosphate dihydrate (CPPD) crystal desposition is described in five English kindreds. Two families were characterized by premature-onset polyarticular CC with little associated structural arthropathy. In one of these families, recurrent childhood fits were strongly associated with subsequent development of CC. Affected members of the other three families resembled sporadic disease in showing predominantly late-onset, oligoarticular CC with mild arthritis and destructive change in only one case. Knee synovial fluid levels of inorganic pyrophosphate (PPi) and nucleoside triphosphate pyrophosphatase (NTPP) did not differ from those of 59 sporadic cases of CC due to CPPD, although PPi and NTPP levels in both groups were higher than in normal knee synovial fluid (P<0.0001). Urinary PPi levels were not different from normal controls. Screening for other metabolic abnormality was negative in all cases. This is the first report of familial CC in the UK, and the first to associate this condition with childhood fits. Absence of overt primary abnormality of PPi metabolism suggests that other factors relating to crystal nucleation/growth may be more relevant to predisposition in these cases.