Nail-patella syndrome (NPS) is a genetic disorder that results in small, poorly developed nails and kneecaps. It is also referred to as iliac horn syndrome, hereditary onychoostedysplasia, Fong disease or Turner-Kiser syndrome.

The Nail-Patella syndrome is inherited via autosomal dominancy that is linked to aberrancy on human chromosome 9′s q arm (q stands for longer arm), 9q34. This autosomal dominancy means that only a single copy, instead of both, is sufficient for disorder to be expressed in the offspring, meaning that the chance of getting the disorder from an affected parent is 50%. The frequency of the occurrence is 1/50,000. The disorder is linked to the ABO blood group locus. It is associated with LMX1B.

The hallmark features of this syndrome are poorly developed fingernails, toenails, and patellae (kneecaps). Sometimes, this disease causes the affected person to have either no thumbnails or a small piece of a thumbnail on the edge of the thumb. Other common abnormalities include elbow deformities, abnormally shaped pelvis bone (hip bone), and kidney (renal) disease. Also, some research shows that people with NPS are more prone to glaucoma and scoliosis, due to poorly developed spines.

People with nail-patella syndrome may display only a few or many of the recognized signs of this disease. Symptoms vary widely from person to person. Signs even vary within a single family with multiple affected members.

Medical marijuana helps relieve the associated pain. Recent evidence suggests that glaucoma is also part of Nail Patella Syndrome.