Infantile neuroaxonal dystrophy (INAD) is a rare inherited disorder affecting the nerve axons (which are responsible for conducting messages) in the brain and other parts of the body, causing a progressive loss of vision and of physical and mental skills.
INAD is caused by an abnormal build-up of substances in the nerves throughout the brain and body, which prevents them from working properly. These deposits (sometimes called spheroid bodies, because of their appearance under the microscope) are found particularly in the nerve endings going to muscles, skin and conjunctiva (around the eyes).
It is not certain how or why these deposits build up on the nerves, but it is likely that the normal process whereby the body clears unwanted chemicals is not working properly, due to the gene responsible for this action being faulty.
It is a progressive disease and its symptoms get worse over time after beginning. Usually, a baby’s growth starts to decelerate between the ages of 6 months to 3 years. Slowing of motor and mental development may be the first symptoms, which may be followed by loss or reversal of previously acquired skills. Speedy, shaky eye movements and squints can be the first symptoms, followed by lumpiness in the body and legs (more than in the arms).
For the first few years, a baby with INAD will be alert and responsive, despite being increasingly physically impaired. Eventually, because of deterioration in vision, speech, and mental skills, the child will lose touch with its surroundings. Death usually occurs between the ages of 5 to 10 years.
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