Mutations may also lead to the truncation (shortening) of the WRNp protein, leading to the loss of its nuclear localization signal sequence, thus it is no longer transported into the nucleus where it interacts with the DNA. This leads to a reduction in DNA repair. Furthermore, mutated proteins are more likely to be degraded than normal WRNp. Apart from causing defects in DNA repair, its aberrant association with p53 down-regulates the function of p53, leading to a reduction in p53-dependent apoptosis and increasing the survival of these dysfunctional cells. Cells of affected individuals also have reduced lifespan in culture, have more chromosome breaks and translocations and have extensive deletions.Patients with Werner syndrome lose the RecQ helicase activity in the WRN protein because of the loss of its C-terminus region, but the mechanism by which this happens is unclear. The loss of the helicase activity can have far-reaching consequences in terms of cell stability and mutation. One instance of these consequences involves telomeres. It is thought that the WRN helicase activity is important not only for DNA repair and recombination, but also for maintaining telomere length and stability. Thus, WRN helicase is important for preventing catastrophic telomere loss during DNA replication. In a normal cell, the telomeres (the ends of chromosomes) undergo repeated shortening during the cell cycle, which can prevent the cell from dividing and multiplying.
nephrogenic diabetes insipidus) as can be seen in hypercalcemia, medullary nephrocalcinosis of any cause, or in children with Bartter syndrome in whom essential tubular salt reabsorption is compromised.There are several causes of nephrocalcinosis that are typically acute and present only with kidney failure. These include tumor lysis syndrome, acute phosphate nephropathy, and occasional cases of enteric hyperoxaluria. Cause
Nephrocalcinosis is connected with conditions that cause hypercalcemia, hyperphosphatemia, and the increased excretion of calcium, phosphate, and/or oxalate in the urine. A high urine pH can lead to  Nephrocalcinosis but only if it is accompanied by hypercalciuria and hypocitraturia, since having a normal urinary citrate usually inhibits the crystallization of calcium. In conjunction with Nephrocalcinosis, hypercalcemia and hypercalciuria the following can occur:
Primary hyperparathyroidism: Nephrocalcinosis is one of the most common symptoms of primary hyperparathyroidism. Sarcoidosis: Nephrocalcinosis is one of the most common symptoms. Vitamin D: This can cause nephrocalcinosis because of Vitamin D therapy because it increases the absorption of ingested calcium and bone resorption, resulting in hypercalcemia and hypercalciuria. Medullary nephrocalcinosis
Medullary sponge kidney
Distal renal tubular acidosis
Hyperoxaluria
Renal papillary necrosisAnd other causes of hypercalcemia (and thus hypercalciuria)
Immobilization (leading to hypercalcemia and hypercalciuria)
Milk-alkali syndrome
Hypervitaminosis D
Multiple myeloma

Hypercalciuria without hypercalcemia
These conditions can cause nephrocalcinosis in association with hypercalciuria without hypercalcemia:
Distal renal tubular acidosis
Medullary sponge kidney
Neonatal nephrocalcinosis and loop diuretics
Inherited tubulopathies
Chronic hypokalemia
Beta thalassemia

Mechanism
Nephrocalcinosis is caused by an increase in the urinary excretion of calcium, phosphate, and/or oxalate. Nephrocalcinosis is closely associated with nephrolithiasis, and patients frequently present with both conditions, however there have been cases where one occurs without the other.