Fanconi syndrome is known to impair the transportation of various substances; and consequently, the condition is not due to a defect in a particular channel, but a general impairment in the functioning of the proximal tubules of the kidney. Fanconi syndrome may be caused because of defective genes or may be the result of kidney damage. Occasionally, the cause is unknown.
There are a range of disorders underlying the Fanconi syndrome. They may be either inherited or acquired.
Cystinosis is the commonest cause of the syndrome in children.
Other inherited causes are: Lowe Syndrome (an unusual genetic disorder of the kidneys, eyes, and brain), Wilsons disease (genetic disorder that affects copper metabolism), Galactosemia, Fructose Intolerance and Glycogen Storage Disease.
It is also probable, that you may acquire the disease later on in life.
Certain drugs, like, cidofovir, azathioprine, gentamicin, and tetracycline. Consuming expired tetracyclines is an important cause. It may be seen as a side effect of tenofovir, especially, in cases of pre-existing renal damage. In HIV patients, Fanconi syndrome may occur secondary to the administration of the anti-retroviral regime. Lead poisoning is another important etiological factor.
Multiple myeloma is also a known cause.