Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) proopiomelanocortin deficiency ?
    ### Response:
    Proopiomelanocortin (POMC) deficiency causes severe obesity that begins at an early age. In addition to obesity, people with this condition have low levels of a hormone known as adrenocorticotropic hormone (ACTH) and tend to have red hair and pale skin.  Affected infants are usually a normal weight at birth, but they are constantly hungry, which leads to excessive feeding (hyperphagia).
    