In contrast to Hartnup disease and related tubular conditions,<unk>  affects the transport of many different substances, so is not considered to be a defect in a specific channel, but a more general defect in the function of the proximal tubules. Different diseases underlie<unk> ; they can be inherited, congenital, or acquired. Inherited Cystinosis is the most common cause of<unk>  in children. Other recognised causes are Wilson's disease (a genetically inherited condition of copper metabolism), Lowe syndrome, tyrosinemia (type I), galactosemia, glycogen storage diseases, and hereditary fructose intolerance. Two forms, Dent's disease and Lowe syndrome, are X linked. A recently described form of this disease is due to a mutation in the peroxisomal protein EHHADH. This mutation misdirects the EHHADH to the mitochondria. This interferes with respiratory complex I and with beta oxidation of fatty acids. The end result is a decrease in the ability of the mitochondria to produce ATP. It was shown that a specific mutation (R76W) of HNF4A, a gene encoding a transcription factor, causes<unk>  in human. In the kidney, HNF4A is expressed in the proximal tubules specifically. Deletion of Hnf4a in the developing mouse kidney caused<unk>  phenotypes including polyruia, polydipsia, glycosuria, and phosphaturia. The Hnf4a mutant kidney showed a defect in the formation of proximal tubules. Acquired It is possible to acquire this disease later in life. Causes include ingesting expired tetracyclines (where tetracycline changes to form epitetracycline and anhydrotetracycline which damage the proximal tubule), and as a side effect of tenofovir in cases of pre-existing renal impairment. In the HIV population,<unk>  can develop secondary to the use of an antiretroviral regimen containing tenofovir and didanosine. Lead poisoning also leads to<unk> . Multiple myeloma or monoclonal gammopathy of undetermined significance can also cause the condition. Additionally,<unk>  can develop as a secondary or tertiary effect of certain autoimmune disorders.
Fanconi syndrome
Rickets
XMEN disease
McKittrick-Wheelock syndrome
Treacher Collins syndrome
ZTTK syndrome
MEDNIK syndrome
ATR-16 syndrome