Does 6q deletion always involve mental retardation? or can some develope a normal cognitive ability?

No: This is a very rare disorder, so it is difficult to predict in an individual child. However, the cognitive skills of those reported from mental retardation to average intelligence. Proceed as though you expect normal learning. Work with a developmental pediatrician to make sure the child is receiving the services she needs.

Please provide more: specific information from the genetic lab's report of results of your child's Chromosomal Microarray. Exactly where is the deletion on the long arm of Chromosome 6? Is it proximal like Chr.6q11-16, distal like Chr. 6q26-27 or other? The size & location of the missing genetic material determine clinical & Neurodevelopmental findings, or phenotype, & help with prognosis.