Section 11. Kidney and Urinary Tract Disorders

Chapter 146. Tubular and Cystic Kidney Disorders

Topics: Introduction | Renal Tubular Acidosis | Renal Glucosuria | Nephrogenic Diabetes Insipidus | Cystinuria | Fanconi's Syndrome | Hypophosphatemic Rickets | Hartnup Disease | Bartter's Syndrome | Liddle's Syndrome | Polycystic Kidney Disease | Medullary Cystic Disease | Medullary Sponge Kidney | Alport's Syndrome | Nail-Patella Syndrome

Alport's Syndrome

Alport's syndrome (hereditary nephritis) is a hereditary disorder in which kidney function is poor, blood is present in the urine, and deafness and eye abnormalities sometimes occur.

Alport's syndrome is usually caused by a defective gene on the X chromosome, but it sometimes results from an abnormal gene on a nonsex (autosomal) chromosome. Other factors influence how severe the disorder is in a person who has the gene. Females with the defective gene on one of their two X chromosomes usually do not have symptoms, although their kidneys may perform somewhat less efficiently than normal; most of these females have some blood in the urine. Males with the defective gene (males do not have a second X chromosome to compensate for the defect) usually develop kidney failure between the ages of 20 and 30. Many people with the defective gene on only one autosomal chromosome have no symptoms other than blood in the urine, but the urine may also contain varying amounts of protein, white blood cells, and casts (small clumps of material) visible under a microscope. Kidney function in people who have the defective gene on two autosomal chromosomes slowly worsens, and kidney failure usually occurs.

Alport's syndrome can affect organs other than the kidneys. Hearing problems, usually an inability to hear sounds in the higher frequencies, are common. Cataracts can also occur, although less often than hearing loss. Abnormalities of the cornea, lens, or retina sometimes cause blindness. Other problems include a low number of platelets in the blood (thrombocytopenia) and abnormalities that affect several nerves (polyneuropathy).

People who develop kidney failure need to undergo dialysis or receive a kidney transplant. Genetic testing is usually offered to people with Alport's syndrome who want to have children.