Periarthritis associated with basic calcium phosphate crystal deposition and low levels of serum alkaline phosphatase--report of three cases from one family.

Three siblings, 2 women and one man, from an Iranian-Jewish family with low serum levels of alkaline phosphatase (liver fraction) and symptomatic calcific periarthritis of multiple joints are described. Both parents and 2 additional siblings had normal serum alkaline phosphatase levels and no joint symptoms. The disease in the proposita, a 49-year-old woman, showed 3 unusual features: (1) no rise in acute phase serum proteins despite severe attacks of periarthritis; (2) refractoriness to treatment; (3) pure octacalcium phosphate found in a deposit obtained by biopsy.