Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Pallister-Killian mosaic syndrome ?
    ### Response:
    Pallister-Killian mosaic syndrome is a developmental disorder that affects many parts of the body. This condition is characterized by extremely weak muscle tone (hypotonia) in infancy and early childhood, intellectual disability, distinctive facial features, sparse hair, areas of unusual skin coloring (pigmentation), and other birth defects.
    