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Sep 09, 2006
Nail Patella syndrome
by SirGan
 Nail-Patella syndrome is one specific and rare genetic disorder characterized by abnormalities of bone, joints, fingernails and kidneys. In most cases- it is commonly characterized by absent or under-developed kneecaps and thumbnails. Less common medical findings include defects of the upper lip, the roof of the mouth, and unusual skeletal abnormalities. Skeletal abnormalities are also an important symptom of this condition and they may include poorly developed scapulae, sideways bent fingers, clubfoot, scoliosis, and unusual neck bones. Important thing to point out is that experts have found an association between nail-patella syndrome and colon cancer. It is also proven that nail-patella syndrome is associated with open-angle glaucoma, which can sometimes lead to blindness. Patients may also have cataracts, drooping eyelids, or corneal problems such as glaucoma. Every patient should know that symptoms vary significantly from person to person even within a single family with multiple affected members.
Nail-patella syndrome is also known as:
IncidenceIt is estimated to occur in one in 50,000 newborns. The incidence of nephropathy in NPS is reported to be approximately 40% among patients with various degrees of dysfunction. Of these patients, 10% die of renal insufficiency. It is also important to point out that both sexes are equally affected.
The cause of Nail Patella SyndromeWhat is the cause of Nail-Patella syndrome? The answer is simple-genetics! Nail-patella syndrome has been recognized as an inherited disorder for over 100 years. Several researches done in the past have showed that it is caused by mutations in a gene known as LIM Homeobox Transcription Factor 1-Beta (LMX1B). This gene is located on the long arm of chromosome 9.
Symptoms of Nail-Patella syndromeIt is important to point out that symptoms of nail-patella syndrome vary widely between patients and some patients with this disorder do not display symptoms at all. Those who have symptoms, here are some which are most common:
Every patient will probably confirm that the most obvious sign associated with nail-patella syndrome is absent, poorly developed, or unusual fingernails. These symptoms are found in over 80% of patients with this disorder. It is also found that these abnormalities may be found in one or more fingernails. This disease most commonly affects the fingernails of the thumbs and index fingers which are often small and concave with pitting, ridges, splits, and discoloration. Patients have reported that their toenails are less often affected.
It is important to know that kneecap abnormalities are the second most common sign associated with this disorder. What's also characteristic- either one or both kneecaps may be missing or poorly formed. Even when they are present, they are likely to be dislocated. Everyone knows that the patella normally have nice and round shape but the knees of people with nail-patella syndrome may have a square appearance. Besides the kneecap, other support structures including bones, ligaments, and tendons may also be malformed. That’s why, in some cases- patients have big problems with simple walking!
Although not too many people know about this- it could be important to point out that the hip bones of approximately 80% of patients with nail-patella syndrome have unusual bony projections. Some experts named these projections - posterior iliac horns. These spurs are internal and not obvious unless they are detected on x ray. In most cases- they are causing no symptoms what so ever!
Several researches done in the past have show that kidney disease is present in at least 30% of patients with nail-patella syndrome. This is extremely important complication because kidney failure is the most dangerous consequence of nail-patella syndrome. The earliest sign of kidney affection is the presence of protein or blood in the urine. What’s characteristic- kidney involvement is progressive, so early diagnosis and treatment of renal disease is important.
Important thing to know is that the skin on the hands is often wrinkled and loose, but sometimes smooths over the distal joint. Some people with Nail-Patella syndrome also experience a lack of flexibility in the distal knuckle of the fingers.
Every patient should know that there are several skeletal symptoms which may occur in people with this rare disease. In most cases- when we talk about skeletal problems- we should know that patients with nail-patella syndrome simply may not be able to fully straighten their arms at the elbow. Sometimes patients may have some other symptoms such as:
Eye problems are not so common symptoms but they may be present. The fact is also tat they may vary from person to person. The most important thing to know about this is that nail-patella syndrome is associated with open angle glaucoma. What is open-angle glaucoma? Open angle glaucoma is caused by fluid blocked into the front chamber of the eye which is eventually causing an increasing pressure into the eye. If untreated, this increased pressure may lead to permanent damage of the optic nerve and irreversible blindness. Nail-patella syndrome has also been associated with:
Diagnosis
Every patient should know that these last couple of years- genetic testing for nail-patella syndrome is available only through research institutions that are working to further characterize this disorder. Big problem is that genetic testing cannot predict which signs of the disease will develop- nor can genetic testing predict the severity of disease symptoms. That’s why- it isn’t considered to be a first-choice diagnostic tool!
It is logical to assume that, because of visible symptoms- diagnosis of this disease could also be made on simple visual medical clues such as the characteristic abnormalities of the fingernails and kneecaps.
Reasonably- the best possible diagnostic tool is probably the x-ray because the diagnosis is confirmed by images of the affected bones and, when indicated, kidney biopsy. This is very good diagnostic method because the bony pelvic spurs found in 80% of patients with nail-patella syndrome are not associated with any other disease.
Most experts claim that one very effective and useful diagnostic tool could be third-trimester ultrasound. Prenatal diagnosis via genetic testing of cells obtained by chorionic villus could also be extremely useful! Unfortunately- prenatal genetic testing for nail-patella syndrome is not yet widely available and it is being used only in specialized laboratories! Patients should also know that there were some controversies surrounding the use of prenatal testing for such a variable disorder.
Treatment of Nail-Patella syndromeThe fact is that in some cases- treatment is usually not necessary. When required, treatment depends on each patient's specific symptoms. Reasonably- every severe kidney disease is treated with dialysis or a kidney transplant.
The treatment for glaucoma depends upon the nature and severity of each case. Unfortunately- the rule is that glaucoma cannot be cured, but it can be controlled. Eye drops, pills, laser procedures, and surgical operations are used to prevent or slow further damage from occurring. With any type of glaucoma, periodic examinations are very important to prevent vision loss.
When walking becomes painful due to bone, tendon, ligament, or muscle defects- patients should know that wheelchair may be required. Of course- orthopedic surgery may be necessary for congenital foot deformity and hip dislocation.
PrognosisSurvival among patients with nail-patella syndrome is not poor or decreased in any chance- unless they experience renal complications. Some experts claim that it is estimated that 8% of individuals with nail-patella syndrome who come to medical attention eventually die of kidney disease but this isn’t a proven fact!
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