Nail Patella Syndrome
Symptoms of nail-Patella syndrome include missing or underdeveloped nails, irregularly shaped kneecaps, abnormal bony growth in the pelvis, and dislocated joints.

Nail-patella syndrome is an uncommon genetic disease, which is inherited by the offspring from parents in an autosomal dominant manner. The disease commonly affects the nails and kneecap (patellae) of the affected individual, hence its name. However, it can also affect a lot of other body parts as well, such as the kidneys, eyes, and pelvis. The inheritance is estimated to be about 1 in 50,000 individuals.

The signs and symptoms that occur in nail-patella syndrome depend on the body parts involved, but may include:

  • Patella (kneecaps): They could be poorly developed, have a small and irregular size, or be completely missing, causing instability and pain in the knee.
  • Nails: They can be missing, underdeveloped, discolored, split, or pitted.
  • Kidneys: The kidneys may not function properly or there could be a presence of blood and protein in the urine.
  • Pelvis: Associated with abnormal bony growth in the pelvis, which is easily seen in an X-ray and causes pain during pelvic movements.
  • Arms and elbows: Usually associated with difficulty extending the full arm. Dislocated elbow joint or wrist joint is also very commonly seen in the affected individuals.

Other systemic signs and symptoms

What is the pathophysiology of nail-patella syndrome?

The condition occurs due to an inherited genetic abnormality, which results from a mutation in LMX1A and LMX1B genes that are located in the long arm of chromosome 9.

The mutation causes the production of abnormal proteins within the body, which affects the various organs of mesodermal and ectodermal origin, such as the skeletal structures, kidneys, and eyes. This is usually inherited from an affected parent.

How is nail-patella syndrome diagnosed?

Because it is a genetic condition, the diagnosis can be made by extensively analyzing the history of the clinical signs and symptoms and conducting blood works.

Genetic mapping will show loss of LMX1A or LMX1B gene samples in chromosome 9.

Usually, the diagnosis can be easily made during childhood, but it may sometimes be overlooked, and the person remains undiagnosed until the very late stage of their life.

Other names for this condition include:

  • Fong disease
  • Hereditary onycho-osteodysplasia
  • Hereditary osteo-onychodysplasia
  • Österreicher syndrome
  • Pelvic horn syndrome
  • Turner–Kieser syndrome

What are the treatment options for nail-patella syndrome?

There is no curative treatment available as of now for nail-patella syndrome. However, symptomatic management is provided to the patient, which helps improve the quality of life.

  • For glaucoma: Doctors may prescribe eye drops that lower the intraocular pressure. Surgery may be required in advance cases.
  • For bone abnormalities: Doctors may prescribe analgesics to reduce pain and calcium and vitamin D to promote better bone density. Besides, physiotherapy improves the range of motion of the involved joints.
  • For kidney problems: Angiotensin-converting enzyme inhibitors drugs widen the blood vessels. They are given to lower proteinuria and blood pressure. Dialysis or, in extreme cases, kidney transplants can be advised.

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Medically Reviewed on 9/28/2021
References
Choczaj-Kukula A. Nail-Patella Syndrome. Medscape. https://emedicine.medscape.com/article/1106294-overview

Sweeney E, Fryer A, Mountford R, et al. Nail Patella Syndrome: A Review of the Phenotype Aided by Developmental Biology. J Med Genet. 2003;40:153-162. https://jmg.bmj.com/content/40/3/153