Nail Patella Syndrome, a Rare Genetic Disorder

Nail patella syndrome- NPS, is a very uncommon or rare genetic disorder which causes abnormalities of bone, fingernails, joints, kidneys and eyes. Nail Patella Syndrome is characterised with the absence or the under developed kneecaps and thumbnails and is estimated to take place in 1 out of 50,000 new-borns. The symptoms may vary among individuals but most of the people with nail patella syndrome tend to have abnormal nails and have problems with their pelvis, knees and elbow though most of them tend to lead a normal life.

Sometimes the person with the condition may not have any symptoms while some symptoms may be more severe than the others. People with this condition may face abnormal or absence of nails which is quite apparent at the time of birth where the base of the nail is often triangular instead of curved shape while the nails could be underdeveloped, split, discoloured, ridged or pitted. The most severed is the thumbnails which decreases towards the little finger and the toenails are normally not affected as much as the fingernails.

 Besides this, the person also tends to have problem with the other areas of the body which includes the bone, joints, eyes and the kidneys.

Defective Gene – LMX1B

The common features comprises of the absence of kneecaps that are small, irregularly shaped and easily dislocated, incapable to fully extend the arm or turn the palms up while keeping elbows straight, wherein the elbows may angle outwards, bony growth on the pelvic bone which is apparent on x-ray but does not cause much of a problem, increased pressure within the eyes or glaucoma at an early stage, there could be protein in the urine which could be an early sign of kidney problem, that could lead to kidney disease and kidney failure, difficulty in gain weight especially muscles inspite of regular consumption of food and exercise, with a decrease in muscle mass in the upper arms and upper legs area, with receding hairline particularly at the temples.

Most of the people with this condition would have inherited a defective gene known as LMX1B from either of their parents where only one copy of the altered gene is essential to develop this condition.

Diagnosis - Clinical Features/Genetic Testing 

The LMX1B gene are codes for protein which regulates the activity of several other genes and are especially important at the early stage of development of growth of the child’s limbs, kidney and eyes when they are in the womb, while genes are units of DNA which provide instructions in producing the protein that are needed for the body and though there is no family history of this condition at times, in some cases, the LMX1B gene may get mutated or altered spontaneously.

The mutated LMX1B gene could lead to the production of an abnormal protein which does not functions well. Diagnosis of nail patella syndrome is done based on clinical features and when the diagnosis is unclear, genetic testing is done to identify if the person has the mutated LMX1B gene, the cause of NPS that involves taking a sample of blood that may include cells containing the persons’ DNA.