Renal involvement in genetic disease

There are more than 200 inherited disorders in which the kidney is affected and which display a wide range of renal features. Autosomal dominant polycystic kidney disease— affects about 1/1000 individuals and accounts for 7% of cases of endstage renal failure in Western countries. Inheritance is autosomal dominant, with mutations in polycystin 1 responsible for 75% of cases and mutations in polycystin 2 accounting for most of the remainder. May present with renal pain, haematuria, urinary tract infection, or hypertension, or be discovered incidentally on physical examination or abdominal imaging, or by family screening, or after routine measurement of renal function. Commonly progresses to endstage renal failure between 40 and 80 years of age. Main extrarenal manifestations are intracranial aneurysms, liver cysts, and mitral valve prolapse. Alport’s syndrome—X-linked dominant inheritance in 85% of kindreds, with molecular defects involving the gene encoding the α‎-5 chain of the type IV collagen molecule. Males typically present with visible haematuria in childhood, followed by permanent nonvisible haematuria, and later by proteinuria and renal failure. Extrarenal manifestations include perceptive deafness of variable severity and ocular abnormalities. Carrier women often have slight or intermittent urinary abnormalities, but may develop mild impairment of renal function late in life, and a few develop endstage renal disease. In the autosomal recessive form of Alport’s syndrome, renal disease progresses to endstage before 20 to 30 years of age at a similar rate in both affected men and women. Other disorders covered in this chapter include hereditary tubulointerstitial nephritis, hereditary tumours, glomerular structural diseases, metabolic diseases with glomerular involvement (Fabry’s disease), congenital anomalies of the kidney and urinary tract, and other genetic diseases with kidney involvement.