Nail–patella syndrome

Nail–patella syndrome
Nail of a patient with nail–patella syndrome
Classification and external resources
Specialty medical genetics
ICD-10 Q87.2 (ILDS Q87.230)
ICD-9-CM 756.89
OMIM 161200
DiseasesDB 8773
eMedicine ped/1546 derm/813
MeSH C05.550.629
Orphanet 2614

Nail–patella syndrome (NPS) (also known as "HOOD syndrome") is a genetic disorder that results in small, poorly developed nails and kneecaps, but can also affect many other areas of the body, such as the elbows, chest, and hips. The name "nail–patella" can be very misleading because the syndrome often affects many other areas of the body, including even the production of certain proteins.[1]:666 Those affected by NPS may have one or more affected areas of the body, and its severity varies depending on the individual. It is also referred to as iliac horn syndrome, hereditary onychoosteodysplasia (HOOD syndrome), Fong disease or Turner–Kieser syndrome.[2]

Diagnosis of NPS can be made at birth, but is common for it to remain undiagnosed for several generations. While there is no cure available for NPS, treatment is available and recommended.


Nail–patella syndrome is inherited in an autosomal dominant pattern.

The Nail–patella syndrome is inherited via autosomal dominancy linked to aberrancy on human chromosome 9's q arm (the longer arm), 9q34. This autosomal dominancy means that only a single copy, instead of both, is sufficient for the disorder to be expressed in the offspring, meaning the chance of getting the disorder from an affected heterozygous 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 random mutations in the LMX1B gene. Studies have been conducted and 83 mutations of this gene have been identified.[3][4][5]


The skeletal structures of individuals who have this disorder may have pronounced deformities. As reported by several medical doctors, the following features are commonly found in people who suffer from nail–patella syndrome:[6]

Bones and joints

AP radiograph showing a hypoplastic patella in NPS
AP radiograph of the right iliac crest showing a bony exostosis or posterior iliac horn, which is pathognomonic of NPS

Kidney issues may arise such as proteinuria and nephritis. Proteinuria is usually the first sign of renal involvement and either rapidly or years after suffering from asymptomatic proteinuria, renal failure occurs in around 5% of NPS patients. Hypothyroidism, irritable bowel syndrome, attention deficit hyperactivity disorder (ADHD), and thin tooth enamel are associated with NPS, but whether these are related or simply coincidences are unclear.[7]


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. The lack of development, or complete absence of fingernails results from the loss of function mutations in the LMX1B gene. This mutation may cause a reduction in dorsalising signals, which then results in the failure to normally develop dorsal specific structures such as nails and patellae.[8] Other common abnormalities include elbow deformities, abnormally shaped pelvic (hip) bones, and kidney (renal) disease.


Treatment for NPS varies depending on the symptoms observed.

See also


  1. Freedberg, et al. (2003). Fitzpatrick's Dermatology in General Medicine. (6th ed.). McGraw-Hill. ISBN 0-07-138076-0.
  2. James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders. Page 786-7. ISBN 0-7216-2921-0.
  3. 1 2 Sweeney E, Fryer A. "Nail patella syndrome: a review of the phenotype aided by developmental biology". Journal of Medical Genetics. 40 (3): 153–162. doi:10.1136/jmg.2003.
  4. Towers AL, Clay CA, Sereika SM, McIntosh I, Greenspan SL (April 2005). "Skeletal integrity in patients with nail patella syndrome". J. Clin. Endocrinol. Metab. 90 (4): 1961–5. doi:10.1210/jc.2004-0997. PMID 15623820.
  5. Romero P., Sanhueza F., Lopez P., Reyes L., Herrera L. (2011). "c.194 A>C (Q65P) mutation in the LMX1B gene in patients with nail-patella syndrome associated with glaucoma". Molecular vision. 17: 1929–39. PMID 21850167.
  6. Choczaj-Kukula, A., & Janniger, C. K. (2009). Nail–patella syndrome. In emedicine: WebMD. Retrieved October 11, 2009, from WebMD database.
  7. Buatti Chris (August 2007). "Nail-Patella Syndrome". Consultant 360. 47 (8).
  8. Wright M J. "Achondroplasia and nail-patella syndrome: the compound phenotype". Journal of Medical Genetics. 37 (9): 25. doi:10.1136/jmg.37.9.e25.2000.
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