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IgA nephropathy
IgA nephropathy (IgAN), also known as Berger's disease (/bɛərˈʒeɪ/) (and variations), or synpharyngitic glomerulonephritis, is a disease of the kidney (or nephropathy) and the immune system; specifically it is a form of glomerulonephritis or an inflammation of the glomeruli of the kidney. Aggressive Berger's disease (a rarer form of the disease) can attack other major organs, such as the liver, skin and heart.
IgA nephropathy is the most common glomerulonephritis worldwide; the global incidence is 2.5/100,000 per year amongst adults. Aggressive Berger's disease is on the NORD list of rare diseases. 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 IgA vasculitis (formerly known as Henoch–Schönlein purpura [HSP]), which is considered by many to be a systemic form of IgA nephropathy. IgA vasculitis presents with a characteristic purpuric skin rash, arthritis, and abdominal pain, and occurs more commonly in children. HSP is associated with a more benign prognosis than IgA nephropathy. In non-aggressive IgA nephropathy, there is traditionally a slow progression to chronic kidney failure in 25–30% of cases during 20 years.
The classic presentation for the non-aggressive form (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. With both aggressive and non-aggressive Berger's disease, loin pain can also occur. The gross hematuria may resolve after a few days, though microscopic hematuria will persist; it is, however, more common with aggressive Berger's disease for gross hematuria to persist rather than microscopic hematuria. Renal function usually remains normal with non-aggressive Berger's disease, though rarely acute kidney failure may occur (see below). This presentation is more common in younger adults.[citation needed]
A smaller proportion (20–30%), usually the older population, has microscopic hematuria and proteinuria (less than 2 grams/day). These patients may be asymptomatic and only picked up due to urinalysis. Hence, the disease is more commonly diagnosed in situations where screening of urine is compulsory (e.g., schoolchildren in Japan).[citation needed]
Very rarely (5% each), the presenting history is:[citation needed]
A variety of systemic diseases are associated with aggressive IgA nephropathy (Berger's disease) such as liver failure, cancer, celiac disease, systemic lupus erythematosus, rheumatoid arthritis, heart failure, reactive arthritis, ankylosing spondylitis and HIV. Diagnosis of Berger's disease and a search for any associated disease occasionally reveals 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. Non-aggressive Berger's disease may also be associated with any of the above systemic diseases; however, this is rare.[citation needed]
Histologically, IgA nephropathy may show mesangial widening and focal and segmental inflammation. Diffuse mesangial proliferation or crescentic glomerulonephritis may also be present. Immunofluorescence shows mesangial deposition of IgA often with C3 and properdin and smaller amounts of other immunoglobulins (IgG or IgM). Early components of the classical complement pathway (C1q or C4) are usually not seen. Electron microscopy confirms electron-dense deposits in the mesangium that may extend to the subendothelial area of adjacent capillary walls in a small subset of cases, usually those with focal proliferation.[citation needed]
The disease derives its name from deposits of immunoglobulin A (IgA) in a granular pattern in the mesangium (by immunofluorescence), a region of the renal glomerulus. The mesangium by light microscopy may be hypercellular and show increased deposition of extracellular matrix proteins. In terms of the renal manifestation of Henoch–Schönlein purpura, it has been found that although it shares the same histological spectrum as IgA nephropathy, a greater frequency of severe lesions such as glomerular necrosis and crescents was observed. Correspondingly, HSP nephritis has a higher frequency of glomerular staining for fibrin compared with IgAN, but with an otherwise similar immunofluorescence profile.
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IgA nephropathy
IgA nephropathy (IgAN), also known as Berger's disease (/bɛərˈʒeɪ/) (and variations), or synpharyngitic glomerulonephritis, is a disease of the kidney (or nephropathy) and the immune system; specifically it is a form of glomerulonephritis or an inflammation of the glomeruli of the kidney. Aggressive Berger's disease (a rarer form of the disease) can attack other major organs, such as the liver, skin and heart.
IgA nephropathy is the most common glomerulonephritis worldwide; the global incidence is 2.5/100,000 per year amongst adults. Aggressive Berger's disease is on the NORD list of rare diseases. 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 IgA vasculitis (formerly known as Henoch–Schönlein purpura [HSP]), which is considered by many to be a systemic form of IgA nephropathy. IgA vasculitis presents with a characteristic purpuric skin rash, arthritis, and abdominal pain, and occurs more commonly in children. HSP is associated with a more benign prognosis than IgA nephropathy. In non-aggressive IgA nephropathy, there is traditionally a slow progression to chronic kidney failure in 25–30% of cases during 20 years.
The classic presentation for the non-aggressive form (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. With both aggressive and non-aggressive Berger's disease, loin pain can also occur. The gross hematuria may resolve after a few days, though microscopic hematuria will persist; it is, however, more common with aggressive Berger's disease for gross hematuria to persist rather than microscopic hematuria. Renal function usually remains normal with non-aggressive Berger's disease, though rarely acute kidney failure may occur (see below). This presentation is more common in younger adults.[citation needed]
A smaller proportion (20–30%), usually the older population, has microscopic hematuria and proteinuria (less than 2 grams/day). These patients may be asymptomatic and only picked up due to urinalysis. Hence, the disease is more commonly diagnosed in situations where screening of urine is compulsory (e.g., schoolchildren in Japan).[citation needed]
Very rarely (5% each), the presenting history is:[citation needed]
A variety of systemic diseases are associated with aggressive IgA nephropathy (Berger's disease) such as liver failure, cancer, celiac disease, systemic lupus erythematosus, rheumatoid arthritis, heart failure, reactive arthritis, ankylosing spondylitis and HIV. Diagnosis of Berger's disease and a search for any associated disease occasionally reveals 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. Non-aggressive Berger's disease may also be associated with any of the above systemic diseases; however, this is rare.[citation needed]
Histologically, IgA nephropathy may show mesangial widening and focal and segmental inflammation. Diffuse mesangial proliferation or crescentic glomerulonephritis may also be present. Immunofluorescence shows mesangial deposition of IgA often with C3 and properdin and smaller amounts of other immunoglobulins (IgG or IgM). Early components of the classical complement pathway (C1q or C4) are usually not seen. Electron microscopy confirms electron-dense deposits in the mesangium that may extend to the subendothelial area of adjacent capillary walls in a small subset of cases, usually those with focal proliferation.[citation needed]
The disease derives its name from deposits of immunoglobulin A (IgA) in a granular pattern in the mesangium (by immunofluorescence), a region of the renal glomerulus. The mesangium by light microscopy may be hypercellular and show increased deposition of extracellular matrix proteins. In terms of the renal manifestation of Henoch–Schönlein purpura, it has been found that although it shares the same histological spectrum as IgA nephropathy, a greater frequency of severe lesions such as glomerular necrosis and crescents was observed. Correspondingly, HSP nephritis has a higher frequency of glomerular staining for fibrin compared with IgAN, but with an otherwise similar immunofluorescence profile.