Nail-patella syndrome

Nail-patella syndrome is characterized by abnormalities of the 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. The fingernails are more likely to be affected than the toenails, and the thumbnails are usually the most severely affected. In many people with this condition, the areas at the base of the nails (lunulae) are triangular instead of the usual crescent shape.

Individuals with nail-patella syndrome also commonly have skeletal abnormalities involving the knees, elbows, and hips. The kneecaps (patellae) are small, irregularly shaped, or absent, and dislocation of the 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. The elbows may also be angled outward (cubitus valgus) or have abnormal webbing. Many individuals with nail-patella syndrome have horn-like outgrowths of the iliac bones of the pelvis (iliac horns). These abnormal projections may be felt through the skin, but they do not cause any symptoms and are usually detected on a pelvic x-ray. Iliac horns are very common in people with nail-patella syndrome and are rarely, if ever, seen in people without this condition.

Other areas of the body may also be affected in nail-patella syndrome, particularly the eyes and kidneys. Individuals with this condition are at risk of developing increased pressure within the eyes (glaucoma) at an early age. Some people develop kidney disease, which can progress to kidney failure.

How common is nail-patella syndrome?

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

What genes are related to nail-patella syndrome?

Mutations in the LMX1B gene cause nail-patella syndrome. The LMX1B gene provides instructions for producing a protein that attaches (binds) to specific regions of DNA and regulates the activity of other genes. On the basis of this role, the LMX1B protein is called a transcription factor. The LMX1B protein appears to be particularly important during early embryonic development of the limbs, kidneys, and eyes. Mutations in the LMX1B gene lead to the production of an abnormally short, nonfunctional protein or affect the protein's ability to bind to DNA. It is unclear how mutations in the LMX1B gene lead to the signs and symptoms of nail-patella syndrome.

Read more about the LMX1B gene.

How do people inherit nail-patella syndrome?

Nail-patella syndrome is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In most cases, an affected person inherits the mutation from one affected parent. Other cases may result from new mutations in the LMX1B gene. These cases occur in people with no history of the disorder in their family.

What other names do people use for nail-patella syndrome?

• Fong disease
• Hereditary onycho-osteodysplasia
• Hereditary Osteo-Onychodysplasias
• Osterreicher Syndrome
• Pelvic Horn Syndrome
• Turner-Kieser Syndrome

Where can I find information about treatment for nail-patella syndrome?

These resources address the management of nail-patella syndrome and may include treatment providers.

• Gene Review: Nail-Patella Syndrome

You might also find information on treatment of nail-patella syndrome in Educational resources and Patient support.

Where can I find additional information about nail-patella syndrome?

You may find the following resources about nail-patella syndrome helpful. These materials are written for the general public.

• MedlinePlus - Health information (3 links)
• Additional NIH Resources - National Institutes of Health
• National Eye Institute: Glaucoma
• Educational resources - Information pages (6 links)
• Patient support - For patients and families (4 links)

You may also be interested in these resources, which are designed for healthcare professionals and researchers.

• Gene Reviews - Clinical summary
• Gene Tests - DNA tests ordered by healthcare professionals
• ClinicalTrials.gov - Linking patients to medical research
• PubMed - Recent literature
• OMIM - Genetic disorder catalog (2 links)

See How are genetic conditions and genes named? in the Handbook.

What if I still have specific questions about nail-patella syndrome?

• See How can I find a genetics professional in my area? in the Handbook.
• Ask the Genetic and Rare Diseases Information Center.
• Submit your question to Ask the Geneticist.

Where can I find general information about genetic conditions?

The Handbook provides basic information about genetics in clear language.

• What does it mean if a disorder seems to run in my family?
• What are the different ways in which a genetic condition can be inherited?
• If a genetic disorder runs in my family, what are the chances that my children will have the condition?
• Why are some genetic conditions more common in particular ethnic groups?

These links provide additional genetics resources that may be useful.

• Genetics and health
• Resources for Patients and Families
• Resources for Health Professionals

What glossary definitions help with understanding nail-patella syndrome?

autosomal ; autosomal dominant ; cell ; dislocation ; DNA ; embryonic ; gene ; glaucoma ; kidney ; mutation ; new mutation ; patella ; pelvis ; prevalence ; protein ; sign ; symptom ; syndrome ; transcription ; transcription factor ; x-rays

References

• Bongers EM, Huysmans FT, Levtchenko E, de Rooy JW, Blickman JG, Admiraal RJ, Huygen PL, Cruysberg JR, Toolens PA, Prins JB, Krabbe PF, Borm GF, Schoots J, van Bokhoven H, van Remortele AM, Hoefsloot LH, van Kampen A, Knoers NV. Genotype-phenotype studies in nail-patella syndrome show that LMX1B mutation location is involved in the risk of developing nephropathy. Eur J Hum Genet. 2005 Aug;13(8):935-46. PubMed citation
• Gene Review: Nail-Patella Syndrome
• McIntosh I, Dunston JA, Liu L, Hoover-Fong JE, Sweeney E. Nail patella syndrome revisited: 50 years after linkage. Ann Hum Genet. 2005 Jul;69(Pt 4):349-63. PubMed citation
• Sweeney E, Fryer A, Mountford R, Green A, McIntosh I. Nail patella syndrome: a review of the phenotype aided by developmental biology. J Med Genet. 2003 Mar;40(3):153-62. PubMed citation