Polycystic Kidney Disease
Polycystic Kidney Disease – Autosomal Recessive PKD
What Is Autosomal Recessive PKD?
Autosomal recessive PKD is caused by a particular genetic flaw that is different from the genetic flaw that causes autosomal dominant PKD. Parents who do not have the disease can have a child with the disease if both parents carry the abnormal gene and both pass the gene to their baby. The chance of this happening (when both parents carry the abnormal gene) is one in four. If only one parent carries the abnormal gene, the baby cannot get the disease.
The symptoms of autosomal recessive PKD can begin before birth, so it is often called “infantile PKD.” Children born with autosomal recessive PKD usually develop kidney failure within a few years. Severity of the disease varies. Babies with the worst cases die hours or days after birth. Children with an infantile version may have sufficient renal function for normal activities for a few years. People with the juvenile version may live into their teens and twenties and usually will have liver problems as well.
What Are the Symptoms of Autosomal Recessive PKD?
Children with autosomal recessive PKD experience high blood pressure, urinary tract infections, and frequent urination. The disease usually affects the liver, spleen, and pancreas, resulting in low blood-cell counts, varicose veins, and hemorrhoids. Because kidney function is crucial for early physical development, children with autosomal recessive PKD are usually smaller than average size.
How Is Autosomal Recessive PKD Diagnosed?
Ultrasound imaging of the fetus or newborn baby reveals cysts in the kidneys but does not distinguish between the cysts of auto-somal recessive and autosomal dominant PKD. Ultrasound examination of kidneys of relatives can be helpful; for example, a parent or grandparent with autosomal dominant PKD cysts could help confirm diagnosis of autosomal dominant PKD in a fetus or child. (It is extremely rare, although not impossible, for a person with autosomal recessive PKD to become a parent.) Because autosomal recessive PKD tends to scar the liver, ultrasound imaging of the liver also aids in diagnosis.
How Is Autosomal Recessive PKD Treated?
Medicines can control high blood pressure in autosomal recessive PKD, and antibiotics can control urinary tract infections. Eating increased amounts of nutritious food improves growth in children with autosomal recessive PKD. In some cases, growth hormones are used. In response to kidney failure, autosomal recessive PKD patients must receive dialysis or transplantation. (See End-Stage Renal Disease)
Genes are segments of DNA, the long molecules that reside in the nuclei of your body’s cells. The genes, through complex processes, cause chemical activities that lead to growth and maintenance of the body. At conception, DNA (and therefore genes) from both parents are passed to the child.
A genetic disease occurs when one or both parents pass abnormal genes to a child at conception. If receiving an abnormal gene from just one parent is enough to produce a disease in the child, the disease is said to have dominant inheritance. If receiving abnormal genes from both parents is needed to produce disease in the child, the disease is said to be recessive.
The chance of acquiring a dominant disease (one gene copy is enough) is higher than the chance of acquiring a recessive disease (two gene copies are needed). A child who receives only one gene copy for a recessive disease at conception will not develop the genetic disease (such as autosomal recessive PKD), but could pass the gene to the following generation.
Acquired Cystic Kidney Disease
What Is ACKD?
ACKD develops in kidneys with long-term damage and bad scarring, so it often is associated with dialysis and end-stage renal disease. About 90 percent of people on dialysis for 5 years develop ACKD. People with ACKD can have any underlying kidney disease, such as glomerulonephritis or kidney disease of diabetes.
The cysts of ACKD may bleed. Kidney tumors, including kidney (renal) cancer, can develop in people with ACKD. Renal cancer is rare yet occurs at least twice as often in ACKD patients as in the general population.
How Is ACKD Diagnosed?
Patients with ACKD usually seek help because they notice blood in their urine (hematuria). The cysts bleed into the urinary system, which discolors urine. Diagnosis is confirmed using ultrasound, CT scan, or MRI of the kidneys.
How Is ACKD Treated?
Most ACKD patients are already receiving treatment for kidney problems. In rare cases, surgery is used to stop bleeding of cysts and to remove tumors or suspected tumors.The Search for PKD Genes
Scientists have not determined the processes that trigger formation of PKD cysts. However, in recent years progress has been made in understanding the abnormal genes responsible for autosomal dominant and autosomal recessive PKD. Scientists have not yet developed clinical tests that determine whether a person carries a PKD gene.
In 1985, scientists narrowed their hunt for a PKD gene to a particular portion of human chromosome 16. In 1994, they precisely identified a gene associated with the vast majority of cases of autosomal dominant PKD. They named the gene “PKD1,” knowing that one or more additional genes for autosomal dominant PKD have yet to be found. By 1995, scientists had produced a map of the PKD1 gene, showing all of its molecular components.
Scientists have continued to search for the autosomal recessive PKD gene. By 1995, they knew that a gene responsible for at least some cases of autosomal recessive PKD resides on chromosome 6.
Scientists will study PKD genes to learn their effects on chemical processes in the body. Knowing the effects will lead to better treatments for the diseases. Eventually, scientists may be able to correct genetic defects, eliminating the diseases entirely.
Points to Remember
The three types of PKD are:Two inherited forms: A common form usually causes symptoms in midlife. A rare form usually causes symptoms in early childhood. A noninherited form is associated with long-term kidney problems, dialysis, and old age.
The signs of PKD include:Pain in the back and lower sides Headaches Urinary tract infections Blood in the urine Cysts in the kidneys and other organs.
Diagnosis of PKD is obtained by:Ultrasound imaging of kidney cysts Ultrasound imaging of cysts in other organs Family medical history.
PKD has no cure. Treatments include:Medicine and surgery to reduce pain Antibiotics to resolve infections Dialysis and transplantation to replace functions of failed kidneys. Additional Resources
Polycystic Kidney Research Foundation
4901 Main Street
Kansas City, MO 64112
American Association of Kidney Patients
100 South Ashley Drive
Tampa, FL 33602
National Kidney Foundation
30 East 33rd Street
New York, NY 10016
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The National Kidney and Urologic Diseases Information Clearinghouse (NKUDIC) is a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). The NIDDK is part of the National Institutes of Health under the U.S. Public Health Service. Established in 1987, the clearinghouse provides information about diseases of the kidneys and urologic system to people with kidney and urologic disorders and to their families, health care professionals, and the public. NKUDIC answers inquiries; develops, reviews, and distributes publications; and works closely with professional and patient organizations and Government agencies to coordinate resources about kidney and urologic diseases.
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NIH Publication No. 96-4008