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Nail Patella Syndrome (NPS) also known Fong Disease. Nail-Patella syndrome (NPS) is a rare genetic disorder and those affected may have small or absent patellae (kneecaps), underdeveloped nails and an inability to fully straighten the elbows.  It has been recognized as a hereditary condition for over 100 years and is inherited in an autosomal dominant manner. Less common medical findings include defects of the upper lip, the roof of the mouth, and unusual skeletal abnormalities. Skeletal abnormalities may include poorly developed scapulae (shoulder blades), sideways bent fingers (clinodactyly), clubfoot, scoliosis, and unusual neck bones. There are also other effects, such as thickening of the basement membrane in the skin and of the tiny clusters of capillaries (glomeruli) in the kidney. Scientists have recognized an association between nail-patella syndrome and colon cancer. Nail changes are seen in 98% of patients with NPS but they may be subtle. Nails may be missing, small or abnormal, ridged, pitted, discoloured, separated into two halves by a ridge of skin, thin or less often, thickened. Nail changes may be noticeable at birth and are most often on both hands and are usually symmetrical.

Nail-patella syndrome is associated with open-angle glaucoma, which, if untreated, may lead to blindness. The gene for NPS, which was just recently discovered, is located on Chromosome 9q34 and is called LMX1B. Patients may also have cataracts, drooping eyelids (ptosis), or corneal problems such as glaucoma. 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. The incidence of nail-patella syndrome is approximately one in 50,000 births. This disorder affects males and females equally. It is found throughout the world and occurs in all ethnic groups. The strongest risk factor for nail-patella syndrome is a family history of the disease. The LMX1B gene codes for a protein that is important in organizing embryonic limb development. Mutations in this gene have been detected in many unrelated people with nail-patella syndrome. Scientists have also been able to interrupt this gene in mice to produce defects similar to those seen in human nail-patella syndrome.

Kidney problems are sometimes worsened by pregnancy, and women with no history of renal problems can also experience pregnancy-related kidney problems like toxemia and pre-eclampsia. Kidney problems (see entry, Kidney disease) can occur in people with NPS at any age. Absence or hypoplasia (underdevelopment) of the kneecaps (patella) and deformities of the knee joint itself often give them a “squarish” look. Ankle edema and recurrent urinary tract infections can also be manifestations of renal involvement. Other problems seen more frequently in NPS include Irritable Bowel syndrome, constipation and poor circulation in the hands and feet with occasional numbness and tingling. NPS does not affect intelligence but there may be a link with Attention Deficit.The most obvious sign associated with nail-patella syndrome is absent, poorly developed, or unusual fingernails. Fingernail abnormalities are found in over 80% of patients with this disorder. Abnormalities may be found in one or more fingernails. Only rarely are all fingernails affected. This disease most commonly affects the fingernails of the thumbs and index fingers. 

Nail Patella Syndrome Treatment and Prevention Tips

1. Treatment, when required, depends on each patient’s specific symptoms. Severe kidney disease is treated with dialysis or a kidney transplant. Patients receiving kidney transplants do not develop nail-patella type renal complications in their new kidney.

2. Although more than 90% of patients with NPS have patellar involvement, most patients are asymptomatic and rarely require surgical treatment.

3. Associated abnormalities require appropriate care from specialists.

4. Eye drops, pills, laser procedures, and surgical operations are used to prevent or slow further damage from occurring.

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