Definition of Onychoosteodysplasia

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Onychoosteodysplasia: This is the nail-patella syndrome, an hereditary condition characterized by abnormally formed (dysplastic) or absent nails and by absent or underdeveloped (hypoplastic) kneecaps (patellae).

Other features of the syndrome include:

• Iliac horns,
• Abnormality of the elbows interfering with full range of motion (pronation and supination), and
• Kidney disease resembling glomerulonephritis, which is often mild but can be progressive and lead to renal failure.

Nail-patella syndrome is inherited as dominant gene. This means that the disease can be transmitted by an affected parent. The nail-patella gene locus was found linked genetically to the ABO blood group locus in 1965 and is now known to be in chromosome region 9q34.

The disorder is also known as Fong disease and Turner-Kieser syndrome. Dr. Fong in 1946 did an intravenous pyelography (IVP) and on X-ray saw the 'iliac horns' (symmetrical bilateral central posterior iliac processes) which are a characteristic feature of the disease. The Turner-Kieser syndrome came about because Henry H. Turner (1892-1970), an Oklahoma endocrinologist, described 2 families with the disease in 1933. His name is more commonly associated with the Turner syndrome that affects about 1 in 2000 newborn girls and is due a missing or abnormal X chromosome.