Novel ANKH amino terminus mutation (Pro5Ser) associated with early-onset calcium pyrophosphate disease with associated phosphaturia.

This report describes a 32-year-old woman presenting since childhood with progressive calcium pyrophosphate disease (CPPD), characterized by severe arthropathy and chondrocalcinosis involving multiple peripheral joints and intervertebral disks. Because ANKH mutations have been previously described in familial CPPD, the proband's DNA was assessed at this locus by direct sequencing of promoter and coding regions and revealed 3 sequence variants in ANKH. Sequences of exon 1 revealed a novel isolated nonsynonymous mutation (c.13 C>T), altering amino acid in codon 5 from proline to serine (CCG>TCG). Sequencing of parental DNA revealed an identical mutation in the proband's father but not the mother. Subsequent clinical evaluation demonstrated extensive chondrocalcinosis and degenerative arthropathy in the proband's father. In summary, we report a novel mutation, not previously described, in ANKH exon 1, wherein serine replaces proline, in a case of early-onset severe CPPD associated with metabolic abnormalities, with similar findings in the proband's father.

Familial hypokalemia/hypomagnesemia and chondrocalcinosis.

OBJECTIVE: Familial occurrence of Bartter's syndrome is well known, but the simultaneous occurrence of hypokalemia/hypomagnesemia and chondrocalcinosis in one family has not been described. We present the clinical, laboratory and radiological findings of a family, in which 7 members were affected by disease. METHODS: A total of 43 members of the family could be interviewed concerning their general health, past diseases and joint complaints. Serum potassium and magnesium were determined in all and radiographic studies were performed in those who had hypokalemia and hypomagnesemia or those with merely articular complaints. Urinary excretion of potassium, magnesium and calcium were determined in the affected persons. RESULTS: Seven patients were found with hypokalemia and hypomagnesemia. Urinary potassium and magnesium excretion was inappropriately high when compared to the serum levels of these electrolytes. All patients had hypocalciuria and extensive chondrocalcinosis, mainly in the knees, elbows and shoulders. In one patient, most probably as a result of magnesium supplementation, a striking reduction of chondrocalcinosis was observed during a followup of 10 years. CONCLUSION: A family with familial hypokalemia/hypomagnesemia and chondrocalcinosis is described. The reduction of chondrocalcinosis, after years of magnesium supplementation in one patient, suggests that hypomagnesemia is an important factor in the pathogenesis of chondrocalcinosis in these patients.