Nail-patella syndrome

A.Prof Frank Gaillard et al.

Nail-patella syndrome, also known as Fong disease or osteo-onychodysostosis, is a rare autosomal dominant condition which results from symmetrical mesodermal and ectodermal abnormalities.

Clinically, the key feature is absent/hypoplastic nails from birth. Individuals may have flexion contractures and recurrent knee dislocations.

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The underlying genetic defect is caused by loss-of-function mutations in the transcription factor LMX1B on chromosome 9 5-6.

Diagnostic radiographic findings include:

  • absent/hypoplastic patellae (with a tendency to recurrent dislocation)
  • hypoplasia of the radial head or capitellum (leading to subluxation/dislocation)
  • bilateral posterior iliac horns ("Fong's prongs") 
  • protuberant anterior iliac spines

The bilateral posterior iliac horns, due to exostoses arising from the posterior aspect of the iliac bones, are present in as many as 80% of patients; this finding is considered pathognomonic for the syndrome. The horns may be capped by an epiphysis. Other features include:

For absent patella(e), consider: 

Iliac horns were described by Edward Everett Fong (b. 1912), an American radiologist.

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Article information

rID: 1714
Section: Syndromes
Synonyms or Alternate Spellings:
  • Osteo-onychodysplasia
  • Fong disease
  • Fong's disease
  • Trauner-Rieger syndrome
  • Hereditary onychoosteodysplasia
  • osteo-onychodysostosis

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Cases and figures

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    Case 1: close up
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    Iliac horn

Exost...
    Case 2
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    Bilateral absent ...
    Case 3
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    Case 4
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    Case 5
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    Case 6
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    Case 7: large tibial tuberosities
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