Nail-patella syndrome (NPS) is a hereditary condition where the growth of a person’s nails and certain bony areas of the body are affected. Nail and patella (kneecap) involvement are the most common places to have changes, however other skeletal parts of the body may also have deformities such as the elbows, chest, spine and hips. Nail-patella syndrome does not usually involve the toenails.
NPS is usually discovered after a person goes to the doctor because of knee pain or inability to extend their leg. As the doctor examines them, classic symptoms of nail growth impairment such as missing nails, especially thumbnails, or the nail not growing to the end of the finger are noticed. Other nails changes may be found such splitting, ridging, spooning of nails or changes in the shape of the moon area of the nail. The person may also indicate that they have excessively sweaty hands.
Further checking of the urine for kidney involvement and the rest of the body for other bony malformations such limited elbow movement may lead the doctor to suspect and eventually diagnose nail-patella syndrome. NPS is not a common condition and is estimated to only occur in only one out of 50,000 people.
Since NPS is a genetic disease, there is no treatment to reverse it but the person should be aware that they could pass it on to their children. Even though 90 percent of people with NPS have patella involvement, usually dislocation or a deformed shape, surgery is not typically needed unless the person has permanent dislocations of the kneecaps.
The greatest risk NPS patient have is the development of eye and kidney disease. In the 1990’s, Dr. Paul Lichner, an ophthalmologist at University of Michigan, noticed that one of his patients with glaucoma had no thumbnail. He recalled that the patient’s mother, who he had also treated for glaucoma, did not have a thumbnail either and it motivated him to determine if there was a connection.
Dr. Lichner’s research team examined 24 people from two families and found over half of them had glaucoma.