Nail-patella syndrome: An hereditary condition characterized by abnormally formed or absent nails and underdeveloped or absent kneecaps (patellae). Other features include:
- Iliac horns
- Abnormality of the elbows interfering with full range of motion (pronation and supination)
- Kidney disease resembling glomerulonephritis, which can be progressive and lead to renal failure.
Nail-patella syndrome (NPS) is inherited as an autosomal dominant trait. The risk NPS will be transmitted by an affected parent to each child is 50%. In a pioneering research, the gene for NPS was found in 1965 to be linked genetically to the ABO blood group locus in chromosome region 9q34. NPS is caused by mutations in a gene called LMX1B (the LIM homeo box transcription factor 1, beta gene). NPS is also called Fong disease and Turner-Kieser syndrome.