Table of Contents
Definition of Alport’s Syndrome
Alport’s Syndrome – An inherited genetic disorder in which one, two, or three mutations occur in the GENE that encodes type IV collagen formations, also called basement membranes. The mutations affect up to three of the six protein chains (alpha-3, alpha-4, and alpha-5) that make up type IV collagen, which is a foundation for a number of structures in the body including the glomeruli in the KIDNEYS, COCHLEA in the inner EAR, LENS of the EYE, and alveoli in the LUNGS.
Among the three variations of Alport’s syndrome, two include damage to these other structures as well as to the kidneys. All variations of Alport’s syndrome include kidney damage that manifests as chronic GLOMERULONEPHRITIS (INFLAMMATION of the glomeruli), resulting in progressive scarring and fibrosis of the glomeruli. The fibrotic tissue replaces healthy tissue, preventing normal glomerular function.
The most common inheritance pattern for Alport’s syndrome is X-linked, which affects about 80 percent of those who have the disorder. The syndrome may also occur as an autosomal recessive pattern (15 percent) or an autosomal dominant pattern (5 percent). All types of Alport’s syndrome eventually progress to END-STAGE RENAL DISEASE (ESRD) in nearly everyone who has the disorder, though the rate of progression is highly variable and differs among the three inheritance patterns for the syndrome.
Symptoms and Diagnostic Path
The most common symptom of Alport’s syndrome is HEMATURIA (bloody URINE) that may appear in early childhood, typically following an upper respiratory viral INFECTION such as a cold. As the damage to the kidneys progresses, symptoms expand to include ALBUMINURIA (excessive albumin or protein in the urine) and HYPERTENSION(high BLOOD PRESSURE). About 80 percent of those who have Alport’s syndrome develop neurosensory HEARING LOSS by ADOLESCENCE, and 15 percent have irregularities in the shape of the lens of the eye (lenticonus).
Symptoms in combination with family history strongly suggest Alport’s syndrome, though kidney biopsy is the definitive diagnostic tool. Kidney biopsy, in which the urologist extracts a core of kidney tissue using a large-gauge needle, allows the him or her to determine the absence of any of the three affected protein chains as well as to assess the degree of damage already present. SKIN biopsy can confirm X-linked Alport’s syndrome because the skin in this type of the disorder lacks the alpha-5 protein chain.
Treatment Options and Outlook
Treatment is primarily supportive and targets symptoms such as hypertension, hearing loss, and VISION IMPAIRMENT. For people who reach ESRD, KIDNEY TRANSPLANTATION often offers a viable therapeutic course. With treatment, many people who have Alport’s syndrome are able to enjoy the lifestyles of their choosing well into the fifth or sixth decade of life. The likelihood of RENAL FAILURE increases with age, however.
Risk Factors and Preventive Measures
Because Alport’s syndrome is an inherited genetic disorder, the only risks for this condition are the causative gene mutations. There are no measures to prevent the condition. Early treatment for consequential health conditions and close medical monitoring of kidney function help maintain optimal health.