Research into the causes of schizophrenia is revealing that schizophrenia develops as a result of a number of biological factors, including genetic variation and environment. Now, two new papers have identified three 'micro deletions' (genetic mutations)  and several 'single nucleotide polymorphisms' (where one 'letter' is different in a particular gene) that are significantly more likely to occur in the dna of people with schizophrenia than those without schizophrenia.