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:
- 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 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:
- genu valgum deformity
- flared iliac crests
- open angle glaucoma 6
- prominent tibial tuberosities
- short 5th metacarpal
- renal osteodystrophy
For absent patella(e), consider:
History and etymology
Iliac horns were described by Edward Everett Fong (b. 1912- fl. 1964 9), an American radiologist in 1946 8.
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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