Alport's Syndrome

Key points

• Alport syndrome is an inherited disorder of type IV collagen caused by pathogenic variants in COL4A3, COL4A4 or COL4A5 ; the common X-linked form is due to COL4A5 variants. It should not be described as 'X-linked dominant'.
• Persistent microscopic glomerular haematuria is a hallmark feature.
• Progressive kidney dysfunction may develop, with severity depending on the genetic form and variant.
• Sensorineural hearing loss is a classic extrarenal manifestation.
• Anterior lenticonus is a characteristic ocular feature in some patients, particularly in severe X-linked disease.
• Alport syndrome diagnosis now relies increasingly on genetic testing alongside clinical/family findings; genetic counselling is important.
• MRCP discriminator: familial haematuria + sensorineural deafness ± anterior lenticonus → Alport syndrome.
• Inheritance trap: COL4A5 = X-linked; COL4A3/COL4A4 = autosomal forms. Do not write 'X-linked dominant'.