Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) 18q deletion syndrome ?
    ### Response:
    18q deletion syndrome is a chromosomal condition that results when a piece of chromosome 18 is missing. The condition can lead to a wide variety of signs and symptoms among affected individuals.  Most people with 18q deletion syndrome have intellectual disability and delayed development that can range from mild to severe, but some affected individuals have normal intelligence and development.
    