What is INAD
Infantile Neuroaxonal Dystrophy (INAD) is an ultra-rare (<200 worldwide) inherited neurodegenerative disorder. It destroys axons, the part of the neuron (nerve cell) that carries messages from the brain to other parts of the body through build up of fatty substances (lipids) on the nerves. In the beginning a child with INAD will appear to be developing normally. But around the ages of 6 months to 3 years developmental milestones will begin to slow down and regress. Some of the first signs and symptoms may be changes in a child’s vision like wobbly eye movements or squinting. Other symptoms that present over time include:
- speech and vision problems,
- inability to sit, crawl or walk,
- difficulty holding up or controlling their head,
- coordination and balance problems,
- loss of cognitive function leading to dementia, and
- seizures
It is a progressive disorder so over time symptoms continue to worsen resulting in total loss of vision, muscle coordination and cognition. Heartbreakingly, the typical life expectancy for the child afflicted with INAD is about 10 years.
INAD is an autosomal recessive disorder. This means both parents must carry the defective PLA2G6 gene to pass it onto their child. When both parents carry the mutated gene there is a 25% chance with each pregnancy that their offspring will present with the disease. A lot is still unknown regarding the genetic and metabolic causes of INAD and there is no known cure or treatment that can stop the disease from worsening.
Because it is so rare, and some of the symptoms are common to other neurodegenerative disorders, getting an early and proper diagnosis is very challenging. Sadly, many families will see a meaningful delay between onset of symptoms and diagnosis. This delay can have a negative impact on efforts to manage symptoms. Today the diagnosis can be confirmed through a blood test looking for two changes with the PLA2G6 gene. Other diagnostic tests include EEG for abnormal brain activity, MRI for cerebellar changes, nerve conduction tests, ocular tests and skin/nerve/tissue biopsy. Prenatal tests can also confirm if an unborn baby has inherited the mutated gene.
There is no known cure or treatment that can stop the disease from worsening. Medications may be prescribed to help with symptom management of pain, stiffness, nutrition supplement needs, seizures, sedation. Supportive therapies such as physical, occupational, and speech therapy are recommended.
Researchers around the world are working on preclinical studies of potential therapies. These studies may include enzyme replacement, gene therapy or gene correction as well as potential combination therapy using medications previously approved for other indications. If successful, the next phase of development is controlled clinical trials in humans. If a promising potential treatment emerges, the drug development Sponsor may seek authorization for a Fast Track review process based on a high unmet medical need in a serious condition.