Nail-patella syndrome (also known as Fong disease, osteo-onychodysostosis, Österreicher-Turner syndrome 10, Turner-Kieser syndrome, and Trauner-Rieger syndrome) is a rare autosomal dominant condition which results from symmetrical mesodermal and ectodermal abnormalities.
The underlying genetic defect is caused by loss-of-function mutations in the transcription factor LMX1B on chromosome 9 5,6.
- renal dysfunction 5
Diagnostic radiographic findings include:
- fragmented/absent/hypoplastic patellae (with a tendency to recurrent dislocation)
- hypoplasia of the radial head or capitellum (leading to subluxation/dislocation dorsally)
- bilateral posterior iliac horns ("Fong prongs")
- flared iliac rests 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 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:
- genu valgum deformity (due to asymmetrical development of the femoral condyles)
- flared iliac crests
- open angle glaucoma 6
- prominent tibial tuberosities
- clinodactyly of the 5th finger
- short 5th metacarpal
- mandibular cysts
- renal osteodystrophy
For absent patella(e), consider:
- popliteal pterygium syndrome
- surgical removal of the patella
- small patella syndrome (ischiopatellar dysplasia)
- Meier-Gorlin syndrome
History and etymology
Iliac horns were described by Edward Everett Fong (b. 1912- fl. 1964 9), an American radiologist in 1946 8.
Multidisciplinary teams are required to treat patients with Nail Patella Syndrome, these include orthopedics, pediatricians and for other complications of the conditions: nephrologists, ophthalmologists, general practitioners, dieticians and physiotherapists to name a few 12.
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- 8. FONG EE. Iliac horns (symmetrical bilateral central posterior iliac processes). (1946) Radiology. 47 (5): 517. doi:10.1148/47.5.517 - Pubmed
- 9. Bulletin - Alumni Faculty Association, School of Medicine, University of California, Volume 1. University of California, San Francisco. School of Medicine. Alumni-Faculty Association. 1953.
- 10. Huriet C, Kessler M, Guittienne B, Maurice F, Rauber G. [Hereditary osteo-onychodysplasia, Osterreicher-Turner syndrome with renal involvement]. (1977) Journal d'urologie et de nephrologie. 83 (4-5): 273-8. Pubmed
- 11.Wolfgang Dähnert. Radiology Review Manual. (2018) ISBN: 9781609139438
- 12. Sweeney E, Hoover-Fong J, McIntosh I. Nail-Patella Syndrome. (2014) Pubmed