I am not aware of this medical condition, but a quick google search tells me this is a genetic disorder.
Insurers have the right to evaluate the health risks of people proposed to be covered in the policy. Based on their criteria, they may deny giving policy to customers with certain kind of health history. This one being a genetic disorder that affects your child, insurer may have some reservations in covering the same. IRDA doesn't have a role in deciding the underwriting criteria of insurers. Or more correctly to say, IRDA plays limited role in underwriting.