Membranoproliferative glomerulonephritis ("MPGN"), also known as mesangiocapillary glomerulonephritis, is a type of glomerulonephritis

Glomerulonephritis

Glomerulonephritis, also known as glomerular nephritis, abbreviated GN, is a renal disease characterized by inflammation of the glomeruli, or small blood vessels in the kidneys...

 caused by deposits in the kidney

Kidney

The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...

 glomerular mesangium

Mesangium

The mesangium is an inner layer of the glomerulus, within the basement membrane surrounding the glomerular capillaries. This term is often used interchangeably with mesangial cell, but in this context refers specifically to the intraglomerular mesangial cells. These cells are phagocytic and secrete...

 and basement membrane (GBM

GBM

-Medicine:* Glioblastoma multiforme, a type of brain tumor* Glomerular basement membrane, a part of the glomerulus which helps separate urine from blood-Other:* Game Boy Micro, a portable video game system from Nintendo...

) thickening, activating complement

Complement system

The complement system helps or “complements” the ability of antibodies and phagocytic cells to clear pathogens from an organism. It is part of the immune system called the innate immune system that is not adaptable and does not change over the course of an individual's lifetime...

 and damaging the glomeruli.

MPGN accounts for approximately 4% of primary renal causes of nephrotic syndrome

Nephrotic syndrome

Nephrotic syndrome is a nonspecific disorder in which the kidneys are damaged, causing them to leak large amounts of protein from the blood into the urine....

 in children and 7% in adults.

It should not be confused with membranous glomerulonephritis

Membranous glomerulonephritis

Membranous glomerulonephritis is a slowly progressive disease of the kidney affecting mostly patients between ages of 30 and 50 years, usually Caucasian.It is one of the more common forms of nephrotic syndrome.-Terminology:...

, a condition in where the basement membrane is thickened, but the mesangium is not.

Pathology

Membranoproliferative glomerulonephritis involves deposits at the intraglomerular mesangium.

Appearance

The GBM is rebuilt on top of the deposits, causing a "tram tracking

Tram tracking

Tram tracking is a phrase used to describe findings in medical conditions that bear some resemblance to tramway tracks.-Pulmonology:Tram tracking is a radiologic sign seen with pulmonary edema due to congestive heart failure and in Bronchiectasis...

" appearance under the microscope. Mesangial cellularity is increased.

Type I

Type I the most common by far, is caused by immune complexes depositing in the kidney. It is characterised by subendothelial and mesangial immune deposits.

It is believed to be associated with the classical complement pathway

Classical complement pathway

The Classical pathway of activation of the complement system is a group of blood proteins that mediate the specific antibody response. The main activators of the Classical Pathway are antigen-antibody complexes.-Initiation:...

.

Type II

Type II (sometimes also called "dense deposit disease") is similar to type I. However, it is believed to be associated with the alternative complement pathway

Alternative complement pathway

The alternative pathway of the complement system is an innate component of the immune system's natural defense against infections, which can operate without antibody participation....

.

Spontaneous remissions of MPGN II are rare, approximately half of those affected with MPGN II will progress to end stage renal disease within 10 years.

In many cases, people with MPGN II can develop drusen

Drusen

Drusen are tiny yellow or white accumulations of extracellular material that build up in Bruch's membrane of the eye. The presence of a few small drusen is normal with advancing age, and most people over 40 have some hard drusen...

 which is caused by same deposits within the Bruch's membrane

Bruch's membrane

Bruch's membrane is the innermost layer of the choroid. It is also called the vitreous lamina, because of its glassy microscopic appearance.It is 2–4 μm thick.-Layers:Bruch's membrane consists of five layers :...

 beneath the retinal pigment epithelium (RPE) layer of the eye. Over time vision can deteriorate and subretinal neovascular membranes, macular detachment, and central serous retinopathy

Central serous retinopathy

Central serous retinopathy , also known as central serous chorioretinopathy , is an eye disease which causes visual impairment, often temporary, usually in one eye, mostly affecting males in the age group 20 to 50 but which may also affect women...

 develop.

Recent research suggests that dense deposit disease may not be a membranoproliferative glomerulonephritis subtype.

Type III

Type III is very rare, it is characterized by a mixture of subepithelial deposits and the typical pathological findings of Type I disease.

A candidate gene has been identified on chromosome 1.

Complement component 3 is seen under immunofluorescence

Immunofluorescence

Immunofluorescence is a technique used for light microscopy with a fluorescence microscope and is used primarily on biological samples. This technique uses the specificity of antibodies to their antigen to target fluorescent dyes to specific biomolecule targets within a cell, and therefore allows...

.