Nail-Patella syndrome (NPS): Hereditary-Osteo-Onycho-Dysplasia (HOOD); Fong's disease; Turner-Kieser syndrome

This is a rare genetic condition, and those affected may have small or absent patellae (kneecaps), underdeveloped nails and an inability to fully straighten the elbows. NPS is extremely variable in its features and severity, even within members of the same family. X-rays may show small or absent patellae, dislocated elbows and there may be small extra bony prominences on the rear of the pelvic bones called iliac horns. These do not cause any problems themselves, and can usually only be detected on X-ray. Other features can include talipes (club foot) or an inability to fully straighten the knees. Back pain may be a problem in adults and the small of the back may have an increased curve inwards. Surgery to correct joint problems may sometimes help but should be performed by an experienced surgeon, after scans have been done to investigate the anatomy of the joint which can be very abnormal.

Kidney problems (see entry, Kidney disease) can occur in people with NPS at any age, with leakage of protein in the urine. A person may not be aware of this but if protein leakage becomes more severe there may be associated swelling (see entry, Nephrotic syndrome). Occasionally, kidney failure can occur and it is important for anyone with NPS to have their urine checked every year. In the eyes, people with NPS are more likely to develop Glaucoma, and at an earlier age than in the general population and so it is recommended that this should also be checked for on a regular basis. Other problems seen more frequently in NPS include Irritable Bowel syndrome, constipation and poor circulation in the hands and feet with occasional numbness and tingling. NPS does not affect intelligence but there may be a link with Attention Deficit Hyperactivity Disorder (ADHD). Inheritance patterns
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 and their parents will be unaffected. When inherited, the severity of the child's condition cannot be predicted. The gene which causes NPS is called LMX1B and it is located on Chromosome 9. The diagnosis is made based on clinical findings but genetic testing is possible if required.

Prenatal diagnosis
Genetic testing of a pregnancy for NPS is difficult as the severity to which the child would be affected cannot be predicted. Ultrasound in pregnancy is not a reliable test for NPS but may detect club foot, if present. Pre-eclampsia is more common in pregnant women with NPS.

Medical text written July 2006 by Dr Elizabeth Sweeney, Consultant Clinical Geneticist, Royal Liverpool Children's Hospital, Alder Hey, Liverpool, UK.

Further Online Resources
Medical texts in The Contact a Family Directory are designed to give a short, clear description of specific conditions and rare disorders. More extensive information on this condition can be found on a range of reliable, validated web sites and links to them are included in the CD-ROM version of this Directory. Further information on these resources can be found in our Medical Information on the Internet article.

NAIL-PATELLA SYNDROME UK

Nail-Patella Syndrome UK
PO Box 26415
East Kilbride
Glasgow
G74 1YW
Tel: 0800 121 8298 freephone helpline
e-mail: dobbinsek@btinternet.com
Web: http://www.npsuk.org

Nail-Patella Syndrome UK is a National Registered Charity No. 1095621, established in 2003. It offers support and linking of affected families where possible. The group raises awareness about the condition, fundraises for research and holds a biennual conference. It publishes a newsletter and has information available, details on request. The group is in touch with approximately 150 families.

Group details last confirmed August 2007.