Investigating ANKH and ENPP1 in Slovakian families with chondrocalcinosis

Familial articular chondrocalcinosis (CC) was first reported in 1963. It is characterised by multiple calcifications of hyaline and fibrous cartilage in the joints and intervertebral discs. Mutations in ANKH have been identified in several pedigrees as a monogenic cause for this disorder. ANKH is a key protein in pyrophosphate metabolism and is involved in pyrophosphate transport across the cell membrane. The objective of this work was to screen ANKH and ENPP1, two key genes in pyrophosphate metabolism, in Slovakian kindreds with familial CC. DNA samples from 25 individuals (10 affected, 15 unaffected) from 8 families were obtained. The promoter, coding regions and intron–exon boundaries of ANKH and ENPP1 were sequenced. Twelve DNA sequence variants, six in each gene, were identified. All the variants had been previously identified. None segregated with the disease. Our results suggest that neither ANKH nor ENPP1 mutations are the cause of CC in these families, indicating that possibly other major genes are involved in the aethiopathogenesis of this condition in these families.