Discovery of a genetic link to risk of kidney stones and osteoporosis

A discovery by scientists at deCODE genetics and academic colleagues from Iceland, the Netherlands and Denmark has pointed to a common biological mechanism contributing to both kidney stones and decreased bone mineral density (BMD).

About 60% of the population carry two copies of a single-letter variation in the human genome (SNP) on chromosome 21, putting them at roughly 65% greater likelihood of developing kidney stones than those who carry no copies. This single variant may thus account for more than a quarter of the incidence of kidney stones, and in women carriers it is also associated with decreased BMD at the hip and spine. The study, which involved the analysis of the genomes of some 50,000 patients and controls, is published in the online edition of Nature Genetics and will appear in upcoming print edition of the journal.

The SNP is in the gene encoding claudin 14 (CLDN14), a protein expressed in the kidney and one of a family of membrane proteins that regulate the passage of ions and small solutes between cells. As calcium is a key component both of most kidney stones and of bone, the deCODE team examined the relationship between CLDN14 and the metabolism of calcium. The results suggest that the SNP may be contributing to increased calcium excretion in urine, a major risk factor for kidney stones and also a sign of bone loss.

"This is an exciting finding because it uncovers a highly plausible common biological mechanism leading to two diseases. This offers a potentially attractive new pathway for drug discovery, and the next task is to build on our understanding of how this SNP increases risk of these diseases and how this pathway could be targeted therapeutically to address this risk. As ever, deCODEme subscribers will see this new variant in their profiles, and we look forward building on this discovery," said Kari Stefansson, CEO of deCODE.

Kidney stones are small crystals formed of dissolved minerals, mainly calcium, that form in the kidneys. Smaller stones can simply be passed through urination, though larger ones can block the urinary tract, causing considerable pain and bleeding. Kidney stones affect some 5% of women and 10% of men in the industrialized world. Larger stones can be detected with ultrasound screening and broken up to facilitate passage, though the recurrence rate is high.

deCODE would like to thank all those who participated in this study, as well as the collaborating clinicians and scientists from the Landspitali University Hospital in Reykjavik, Iceland; Radboud University Nijmegen Medical Centre in Nijmegen, Netherlands; Nordic Bioscience A/S in Herlev, Denmark; and the Center for Clinical and Basic Research A/S in Ballerup, Denmark.