A writing disability should not be a bar to participation in a gifted program. If your child's difficulties with writing are severe enough to interfere with his ability to keep up with the written work in classes that are otherwise at his intellectual ability level, then he would most likely qualify as a child with a disability under either Section 504 or IDEA, and should be allowed access to the gifted programming with accommodations such as reduced copywork, keyboarding and/or a scribe for assignments other than handwriting instruction, and possibly occupational therapy services to help remediate his writing difficulties.
See more information
here and
here. 
