Alport's syndrome is usually inherited in an X-linked dominant pattern*. It is due to a defect in the gene which codes for type IV collagen resulting in an abnormal glomerular-basement membrane (GBM).

The disease is more severe in males with females rarely developing renal failure.

A favourite question is an Alport's patient with a failing renal transplant. This may be caused by the presence of anti-GBM antibodies leading to a Goodpasture's syndrome like picture.

• in around 85% of cases - 10-15% of cases are inherited in an autosomal recessive fashion with rare autosomal dominant variants existing

Features

Alport's syndrome usually presents in childhood. The following features may be seen:

• microscopic haematuria
• progressive renal failure
• bilateral sensorineural deafness
• lenticonus: protrusion of the lens surface into the anterior chamber
• retinitis pigmentosa

Investigations

• molecular genetic testing
• renal biopsy
  • electron microscopy: characteristic finding is of the longitudinal splitting of the lamina densa of the glomerular basement membrane, resulting in a 'basket-weave' appearance

To make this diagnosis, you need evidence of hematuria in 3 generations with no family history of renal failure, dialysis and/or transplantation.