You have not mentioned your child's age. If you have a disabled child older than 12 and you pay someone to take care of the child while you work you may still get the child and dependent care credit if you enter the information about the babysitter or childcare provider that you paid. Otherwise, no, there is not a federal credit for having a disabled child. Check your state's tax laws since there are a few states with such credits.
A child's disability doesn't affect tax filing until he turns 19 (24 if a full time student). Then his disability allows him to continue to be considered a "Qualifying Child" for tax purposes* regardless of age. There are no credits or deductions, other than that some items, e.g. special schooling, can be considered medical expenses.
*This is mainly for the Earned Income Credit. The age 17 (18 for 2021) limit still applies for the child tax credit.