What causes a child to partially lose her pigmentation on spots on her face?

Tryptophan. If protein is not digested body does not get enough tryptophan - precursor for both serotonin and melanin. Could be a sign of indigestion. Get tested with metametrix lab - urine organix profile - this can pinpoint the problem. Use aminosport by biotics or neuro-htp by biotics to improve this issue.