Nail-patella syndrome

Last revised by Daniel J Bell on 1 Feb 2022

Nail-patella syndrome, also known as Fong disease, is a rare autosomal dominant condition which results from symmetrical mesodermal and ectodermal abnormalities. Radiologically, the classic findings are the abnormal patellae and posterior iliac horns, the latter is said to be pathognomonic.

Nail-patella syndrome has many synonyms, in addition to Fong disease, which include osteo-onychodysostosisÖsterreicher-Turner syndrome 10Turner-Kieser syndrome, and Trauner-Rieger syndrome.

  • renal dysfunction 5

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

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:

  • fragmented/absent/hypoplastic patellae with a tendency for recurrent patellar dislocation
  • hypoplasia of the radial head and/or capitellum leading to subluxation or dislocation dorsally
  • bilateral posterior iliac horns ("Fong prongs")
  • flared iliac crests with protuberant anterior iliac spines

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

Other features include:

Multidisciplinary teams are required to treat patients with nail-patella syndrome, these include orthopedics, pediatricians, and for other complications of the condition: nephrologists, ophthalmologists, general practitioners, dieticians, and physiotherapists, etc. 11.

Iliac horns were described by Edward Everett Fong (1912-fl.1964 9), an American radiologist in 1946 8.

For absent patella(e), consider:

ADVERTISEMENT: Supporters see fewer/no ads