Nail-patella syndrome, also known as Fong disease, is a rare autosomal dominant condition which results from symmetrical meso and ectodermal abnormalities.
Clinically the key feature is absent/hypoplastic nails from birth. Individuals may have flexion contractures and recurrent knee dislocations.
- renal dysfunction 5
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 are 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. Other features include:
For absent patella(e), consider:
History and etymology
Iliac horns were described by Edward Everett Fong (b. 1912), an American radiologist.
- 1. Carty H. Imaging children. Churchill Livingstone. (2005) ISBN:0443070393. Read it at Google Books - Find it at Amazon
- 2.Gadekar NG, Chawla S, Anand HK. Iliac horns with arthrodysplasia and dystrophy of the nails-Fong's lesion. Br J Radiol. 1962;35 (410): 141-2. doi:10.1259/0007-1285-35-410-141 - Pubmed citation
- 3. Dähnert W. Radiology review manual. Lippincott Williams & Wilkins. (2007) ISBN:0781738954. Read it at Google Books - Find it at Amazon
- 4. Miller TT, Shapiro MA, Schultz E et-al. Sonography of patellar abnormalities in children. AJR Am J Roentgenol. 1998;171 (3): 739-42. AJR Am J Roentgenol (abstract) - Pubmed citation
- 5. Kolhe N, Stoves J, Will EJ et-al. Nail-patella syndrome--renal and musculo-skeletal features. Nephrol. Dial. Transplant. 2002;17 (1): 169-70. doi:10.1093/ndt/17.1.169 - Pubmed citation
- 6. E Sweeney, A Fryer et-al. Nail patella syndrome: a review of the phenotype aided by developmental biology. J Med Genet 2003;40:153-162 doi:10.1136/jmg.40.3.153 - PDF