Nail-patella syndrome is caused by a mutation of a gene that plays an important role in the development of limbs and kidneys.
Commonly, people who have this syndrome are missing one or both kneecaps (patellas), have an arm bone (radius) that is dislocated at the elbow, and have an abnormally shaped pelvic bone.
Their fingernails and toenails are missing or poorly developed, with pitting and ridges.
About 50% of people with this syndrome have blood in their urine Blood in Urine Blood in the urine (hematuria) can make urine appear pink, red, or brown, depending on the amount of blood, how long it has been in the urine, and how acidic the urine is. An amount of blood... read more (hematuria) or protein in their urine (proteinuria). Kidney failure Overview of Kidney Failure Kidney failure is the inability of the kidneys to adequately filter metabolic waste products from the blood. Kidney failure has many possible causes. Some lead to a rapid decline in kidney function... read more eventually develops in about 30% of people with affected kidneys. People who have kidney problems often have high blood pressure High Blood Pressure High blood pressure (hypertension) is persistently high pressure in the arteries. Often no cause for high blood pressure can be identified, but sometimes it occurs as a result of an underlying... read more 
(hypertension).
Diagnosis of Nail-Patella Syndrome
A doctor's evaluation
Sometimes x-rays and biopsy
The diagnosis of nail-patella syndrome is suggested by the symptoms and results of a physical examination.
The diagnosis is confirmed by bone x-rays X-rays A doctor can often diagnose a musculoskeletal disorder based on the history and the results of a physical examination. Laboratory tests, imaging tests, or other diagnostic procedures are sometimes... read more 
and a biopsy of kidney tissue Kidney biopsy Site-specific biopsies and cell sampling are also used in the evaluation of people with suspected kidney and urinary tract disorders. (See also Overview of the Urinary Tract.) A kidney biopsy... read more (removal of a tissue sample for examination under a microscope). Genetic testing also may be done.
People who have blood or protein in their urine may undergo kidney function tests Kidney Function Tests Doctors can assess kidney function by doing tests on blood and urine samples. Creatinine, a waste product, is increased in the blood when kidney function is decreased by a large amount. Creatinine... read more .
Treatment of Nail-Patella Syndrome
Control of blood pressure
Sometimes dialysis or kidney transplantation
There is no effective treatment for nail-patella syndrome.
Controlling high blood pressure and protein in the urine with medications called angiotensin-converting enzyme (ACE) inhibitors Angiotensin-converting enzyme inhibitors High blood pressure is very common. It often does not cause symptoms; however, high blood pressure can increase the risk of stroke, heart attack, and heart failure. Therefore, it is important... read more may slow the rate at which kidney function deteriorates.
People who develop kidney failure need dialysis Dialysis Dialysis is an artificial process for removing waste products and excess fluids from the body, a process that is needed when the kidneys are not functioning properly. There are a number of reasons... read more 
or a kidney transplant Kidney Transplantation Kidney transplantation is the removal of a healthy kidney from a living or recently deceased person and then its transfer into a person with end-stage kidney failure. (See also Overview of Transplantation... read more 
.
Genetic testing should be offered to people who want to have children.
