Nail-patella syndrome is characterized by abnormalities of your nails, knees, elbows, and pelvis.

The features of nail-patella syndrome vary in severity between affected individuals, even among members of the same family.

Nail abnormalities are seen in almost all individuals with nail-patella syndrome.

The nails may be absent or underdeveloped and discolored, split, ridged, or pitted.

Your fingernails are more likely to be affected than your toenails, and your thumbnails are usually the most severely affected.

The areas at the base of your nails may be triangular instead of the usual crescent shape.

If you have nail-patella syndrome you may also have skeletal abnormalities involving your knees, elbows, and hips.

Your kneecaps (patellae) are small, irregularly shaped, or absent, and dislocation of your patella is common.

Some people with this condition may not be able to fully extend their arms or turn their palms up while keeping their elbows straight.

Your elbows may also be angled outward or have abnormal webbing.

Many people with nail-patella syndrome have horn-like outgrowths of the iliac bones of their pelvis (iliac horns).

These abnormalities may be felt through your skin, but they don’t cause symptoms and are usually found on a pelvic x-ray.

Iliac horns are very common in people with nail-patella syndrome and are rarely seen in people without this condition.

Other areas of your body may also be affected, particularly your eyes and kidneys.

Individuals with this condition are at risk of developing glaucoma at an early age.

Some people develop kidney disease, which can progress to kidney failure.

The prevalence of nail-patella syndrome is estimated to be 1 in 50,000 individuals.

Mutations in a particular gene cause nail-patella syndrome.

This gene provides instructions for making a protein that attaches to specific areas of DNA and regulates the activity of other genes.

This protein appears to be particularly important during early embryonic development of the limbs, kidneys, and eyes.

It’s unclear how mutations in this gene lead to the signs and symptoms of nail-patella syndrome.

Nail-patella syndrome is inherited.

In most cases, an affected person inherits the mutation from one affected parent.

Other cases may result from new mutations in this gene.

These cases occur in people with no history of the disorder in their family.

There is no cure for nail-patella syndrome, but there are things you can do to improve your particular symptoms.