Nail–patella syndrome

Nail–patella syndrome
Classification and external resources
Nail of a patient with nail-patella syndrome
ICD-10	Q87.2 (ILDS Q87.230)
ICD-9	756.89
OMIM	161200
DiseasesDB	8773
eMedicine	ped/1546 derm/813
MeSH	C05.550.629

Nail–patella syndrome (NPS) is a genetic disorder that results in small, poorly developed nails and kneecaps, but can also affect many other areas of the body, such as the elbows, chest, and hips. The name "nail-patella" can be very misleading because the syndrome often affects many other areas of the body, including even the production of certain proteins. It is also referred to as iliac horn syndrome, hereditary onychoostedysplasia, Fong disease or Turner–Kiser syndrome.

Genetics

Nail-patella syndrome is inherited in an autosomal dominant pattern.

The Nail-patella syndrome is inherited via autosomal dominancy linked to aberrancy on human chromosome 9's q arm (the longer arm), 9q34. This autosomal dominancy means that only a single copy, instead of both, is sufficient for the disorder to be expressed in the offspring, meaning the chance of getting the disorder from an affected heterozygous parent is 50%. The frequency of the occurrence is 1/50,000.^{[citation needed]} The disorder is linked to the ABO blood group locus.

It is associated with LMX1B.

Symptoms

The skeletal structures of individuals who have this disorder may have pronounced deformities. As reported by several medical doctors, the following features are commonly found in people who suffer from nail–patella syndrome:

Bones and joints

• Patellar involvement is present in approximately 90% of patients; however, patellar aplasia occurs in only 20%.
• In instances in which the patellae are smaller or luxated, the knees may be unstable.
• The elbows may have limited motion (e.g., limited pronation, supination, extension).
• Subluxation of the radial head may occur.
• Arthrodysplasia of the elbows is reported in approximately 90% of patients.
• General hyperextension of the joints can be present.
• Exostoses arising from the posterior aspect of the iliac bones ("iliac horns") are present in as many as 80% of patients; this finding is considered pathognomonic for the syndrome.

• Other reported bone changes include scoliosis, scapular hypoplasia, and the presence of cervical ribs.

• 

  An elbow of a man who suffers from nail-patella syndrome (NPS).

• 

  This is a view from a different angle of the same man's other elbow.

Presentation

The hallmark features of this syndrome are poorly developed fingernails, toenails, and patellae (kneecaps). Sometimes, this disease causes the affected person to have either no thumbnails or a small piece of a thumbnail on the edge of the thumb. Other common abnormalities include elbow deformities, abnormally shaped pelvic (hip) bones, and kidney (renal) disease. Also, some research shows people with NPS are more prone to glaucoma and scoliosis, due to poorly developed spines. People with nail-patella syndrome may display only a few or many of the recognized signs of this disease. Symptoms vary widely from person to person. Signs even vary within a single family with multiple affected members.

See Also

• List of cutaneous conditions

External links

• GeneReview/NCBI/NIH/UW entry on Nail-Patella Syndrome
• Rare Disorders: Stargardt's Disease - Very Detailed Article with Images
• Nail Patella Syndrome UK
• Nail Patella Syndrome Holland
• Nail-Patella Syndrome - Article at National Center for Biotechnology Information