Alport syndrome is a genetic disorder[1] affecting around 1 in 5,000–10,000 children,[2] characterized by glomerulonephritis, end-stage kidney disease, and hearing loss.

Alport syndrome is caused by an inherited defect in type IV collagen—a structural material needed for the normal function of different body parts.

[7] These descriptions refer to 'classic' Alport syndrome, which usually causes significant disease from young adult or late childhood life.

Hearing loss in affected patients develops progressively, usually at the stage when kidney function is normal, but there is substantial proteinuria.

[citation needed] Macular abnormalities such as incomplete foveal hypoplasia or staircase foveopathy are common in Alport syndrome.

Symptoms usually appear in late childhood and include dysphagia, postprandial vomiting, substernal or epigastric pain, recurrent bronchitis, dyspnea, cough, and stridor.

[8] Leiomyomas, tumours of smooth muscle affecting the oesophagus and female genital tract, may occur in a rare overlap syndrome involving the adjacent COL4A5 and COL4A6 genes.

[2] Alport syndrome is caused by mutations in COL4A3, COL4A4, and COL4A5, three of six human genes involved in basement membrane (type IV) collagen biosynthesis.

Mutations in any of these genes prevent the proper production or assembly of the specialised type IV collagen '345' network which is an important structural component of basement membranes in the kidney, inner ear, and eye.

Skin biopsies have been used to show the absence of the COL4A5 gene product, but these techniques are not straightforward, only apply to patients with severe COL4A5 mutations, and are not widely available.

[citation needed] A family history of end-stage renal disease with hearing impairment is suggestive of Alport syndrome, but other conditions can cause this combination of abnormalities.

[citation needed] Genetic testing plays an increasingly important role in confirming the diagnosis where the clinical features do not amount to proof.

[27][28] Gene therapy has been frequently discussed, but delivering it to the podocytes in the glomerulus that normally produce the type IV collagen in the glomerular basement membrane is challenging.

[30] Studies of the life expectancy of patients with Alport syndrome are rare, but one 2012 study found that Alport patients receiving renal replacement therapy (dialysis or kidney transplantation) exhibited, on average, better survival compared with matched controls who had other kidney diseases (and who also received renal replacement therapy).