Nail Patella Syndrome

Nail patella syndrome (NPS) is a rare genetic disorder characterized by abnormalities of the nails, knees, elbows, and pelvis. It is also known as hereditary onycho-osteodysplasia or Fong disease.

Causes and Inheritance

Nail patella syndrome is caused by mutations in the LMX1B gene, which provides instructions for making a protein involved in the development of limbs and other tissues. The condition is inherited in an autosomal dominant pattern, meaning that one copy of the altered gene in each cell is sufficient to cause the disorder.

Symptoms

The symptoms of nail patella syndrome can vary widely among affected individuals, but common features include:

• Abnormalities of the nails, such as:
  • Underdeveloped or absent fingernails and toenails
  • Thin, brittle, or ridged nails
  • Nails that are triangular or V-shaped
• Knee problems, such as:
  • Patellar hypoplasia (underdeveloped kneecap)
  • Patellar dislocation (kneecap out of place)
  • Patellofemoral pain syndrome (pain in the front of the knee)
• Elbow problems, such as:
  • Limited range of motion
  • Pain or stiffness
• Pelvic abnormalities, such as:
  • Hypoplastic (underdeveloped) ilia (the widest and uppermost of the three bones that merge to form the pelvis)
  • Renal problems, such as kidney disease or cysts
• Other possible features:
  • Skeletal abnormalities, such as scoliosis or clubfoot
  • Eye problems, such as glaucoma or cataracts
  • Hearing loss

Diagnosis

Nail patella syndrome is typically diagnosed based on a combination of clinical evaluation, family history, and imaging studies. Diagnostic tests may include:

• X-rays to evaluate the bones and joints
• CT or MRI scans to assess the pelvis and kidneys
• Genetic testing to identify mutations in the LMX1B gene

Treatment and Management

Treatment for nail patella syndrome is usually focused on managing the symptoms and preventing complications. This may include:

• Orthopedic care, such as physical therapy or surgery, to address knee, elbow, or pelvic problems
• Pain management, such as medication or alternative therapies
• Routine monitoring of kidney function and blood pressure
• Regular eye exams to detect potential vision problems
• Hearing tests to assess for hearing loss

Prognosis

The prognosis for individuals with nail patella syndrome varies depending on the severity of the symptoms and the presence of any complications. With proper management, many people with NPS can lead active and fulfilling lives.