Also known as: Fong’s disease; Hereditary-osteo-onycho-dysplasia; Turner-Kieser syndrome
Nail-Patella syndrome (NPS) is a rare genetic condition which may cause problems with the nails, kneecaps, elbows, kidneys and glaucoma.
Medical text written July 2006 by Dr Elizabeth Sweeney. Last updated November 2012, by Dr Elizabeth Sweeney, Consultant Clinical Geneticist, Royal Liverpool Children’s Hospital, Alder Hey, Liverpool, UK.
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.
The gene which when changed (mutated) causes NPS is called LMX1B. It is located on chromosome 9.
The diagnosis is made based on identifying common features during clinical examination, but genetic testing is possible if required.
Management of NPS involves treating the symptoms of the condition. Joint problems in NPS may be treated with physiotherapy or surgery where appropriate. Because the joint anatomy is often abnormal in NPS, magnetic resonance imaging (MRI) scanning may be helpful prior to any surgery. Glaucoma can be treated with medication or surgery and kidney failure can be treated with dialysis or kidney transplantation.
The inheritance pattern is autosomal dominant. Most people will have inherited the condition from one of their parents but for some people the condition will have started for the first time in them. Children of an affected individual have a 50 per cent chance of inheriting the faulty NPS gene, but the severity cannot be predicted.
During a pregnancy, it may be possible to tell whether a baby has inherited the mutated NPS gene by a prenatal test. However, it is not possible to predict how severely the baby would be affected. Ultrasound scans may detect major problems with the limbs (eg club foot), but most of the features of NPS would not be possible to detect on a prenatal ultrasound scan.
There is no support group for Nail-Patella Syndrome in the UK.
Families can use Contact’s freephone helpline for advice, information and, where possible, links to other families. To meet other families with disabled children, join Contact’s closed (private) Facebook group.