NPS is extremely variable even within members of the same family.
Nails may be absent, small, ridged, or separated into two halves by a ridge of skin and the thumbnails are the most severely affected.
The patellae (knee caps) may be normal, small, or absent. Dislocation of the patella is common. There may also be early arthritis of the knees. There may be difficulty fully straightening the elbow and X-rays may show abnormalities of the head of the radius bone. There may be pterygia (a web of skin) across the elbow joint. Iliac horns may be visible on an X-ray of the pelvis. These are cone-shaped, bony bumps on the back of the iliac bones, but do not cause any problems. Some affected babies may be born with club foot (see entry Congenital Talipes Equinovarus). Back pain is common in adults with NPS.
About half of patients with NPS may have problems with their kidneys ranging from proteinuria (passing protein in the urine), to nephrotic syndrome (proteinuria and swelling), to kidney failure in about 3 per cent of people. Proteinuria may start at any age from birth. Kidney problems may occur for the first time during pregnancy or be made worse by pregnancy and there is an increased chance of preeclampsia (a condition causing high blood in pregnancy).
There is an increased risk of glaucoma in NPS and it can occur at a younger age than in the general population. Other problems which are more common in NPS are irritable bowel syndrome, constipation, and poor circulation in the hands and feet with occasional numbness and tingling.