Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Ring chromosome 20 ?
    ### Response:
    Ring chromosome 20 is a chromosome abnormality that affects the development and function of the brain. People with ring chromosome 20 often have recurrent seizures or epilepsy. Other symptoms might include intellectual disability, behavioral difficulties, growth delay, short stature, a small head (microcephaly), and characteristic facial features.
    