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IgA nephropathy (also known as IgA nephritis, IgAN, Berger disease (), Berger's disease, Berger's syndrome, Berger syndrome, or synpharyngitic glomerulonephritis) is a form of glomerulonephritis (inflammation of the glomeruli of the kidney). IgA nephropathy is the most common glomerulonephritis throughout the world. Primary IgA nephropathy is characterized by deposition of the IgA antibody in the glomerulus. There are other diseases associated with glomerular IgA deposits, the most common being Henoch-Schönlein purpura (HSP), which is considered by many to be a systemic form of IgA nephropathy. HSP presents with a characteristic purpuric skin rash, arthritis, and abdominal pain and occurs more commonly in young adults (16-35 yrs old). HSP is associated with a more benign prognosis than IgA nephropathy. In IgA nephropathy there is a slow progression to chronic kidney failure in 25-30% of cases during a period of 20 years. ==Signs and symptoms== The classic presentation (in 40-50% of the cases) is episodic hematuria which usually starts within a day or two of a non-specific upper respiratory tract infection (hence ''synpharyngitic'') as opposed to post-streptococcal glomerulonephritis which occurs some time (weeks) after initial infection. Less commonly gastrointestinal or urinary infection can be the inciting agent. All of these infections have in common the activation of mucosal defenses and hence IgA antibody production. Groin pain can also occur. The gross hematuria resolves after a few days, though microscopic hematuria may persist. These episodes occur on an irregular basis every few months and in most patients eventually subsides (although it can take many years). Renal function usually remains normal, though rarely, acute kidney failure may occur (see below). This presentation is more common in younger adults. A smaller proportion (20-30%), usually the older population, have microscopic hematuria and proteinuria (less than 2 gram/day). These patients may not have any symptoms and are only clinically found if a doctor decides to take a urine sample. Hence, the disease is more commonly diagnosed in situations where screening of urine is compulsory, e.g. schoolchildren in Japan. Very rarely (5% each), the presenting history is: * Nephrotic syndrome (3-3.5 grams of protein loss in the urine, associated with a poorer prognosis) * Acute kidney failure (either as a complication of the frank hematuria, when it usually recovers, or due to rapidly progressive glomerulonephritis which often leads to chronic kidney failure) * Chronic kidney failure (no previous symptoms, presents with anemia, hypertension and other symptoms of kidney failure, in people who probably had longstanding undetected microscopic hematuria and/or proteinuria) A variety of systemic diseases are associated with IgA nephropathy such as liver failure, celiac disease, rheumatoid arthritis, reactive arthritis, ankylosing spondylitis and HIV. Diagnosis of IgA nephropathy and a search for any associated disease occasionally reveals such an underlying serious systemic disease. Occasionally, there are simultaneous symptoms of Henoch-Schönlein purpura; see below for more details on the association. Some HLA alleles have been suspected along with complement phenotypes as being genetic factors. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「IgA nephropathy」の詳細全文を読む スポンサード リンク
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