The term Alport's syndrome describes a heterogenous group of inherited disorders, which are the result of different biochemical defects involving type IV collagen chains. It is characterised by micro/macroscopic haematuria and progression ot renal failure. Mild nephrotic syndrome develops in 40% of cases. Sensorineural hearing loss is detected in most families.
The classic form of Alport's syndrome is an X-linked dominant disease, involving mutations of the gene encoding for the α5-chain of type IV collagen. It accounts for 85% of Alport's cases and all males progress to renal failure, before the age of 30 years. The disease in females is more variable with 10-15% progressing to renal failure.
There is also an autosomal recessive form accounting for 15% of cases. The abnormalities are in the genes encoding for the α3 and α4-chains of type IV collagen, located on chromosome 2.
Rarely there is an autosomal dominant inheritance, where macrothrombocytopaenia is associated with a hearing defect and nephritis.