User:Lugg h/sandbox

Genetics
There is no known single cause or causes of schizophrenia, however, it is a heritable disorder. Currently, the best explanation for the onset of schizophrenia is a multifactorial model between genetics and environmental exposure. Many different genes predetermine an individual to be more sensitive to environmental factors. There is a strong genetic component to schizophrenia. Genetic closeness to someone with schizophrenia increases the chances that a relative will also develop schizophrenia. This genetic relationship is shown in twin studies where it has been found that among monozygotic twins there is a 40-60% chance the twin will also have schizophrenia, whereas among dizygotic twins there is only a 5-15% chance. Research in Denmark, Finland, and the United States all showed that adopted children with biological parents that had schizophrenia were more likely to have schizophrenia than adopted children whose biological parents did not have schizophrenia. Genetic research for schizophrenia has focused on the idea that there are possibly multiple alleles causing schizophrenia each only impacting a small amount. However, it is hard to find a causal relationship between genes and diagnosis. Research has found that children with early-onset schizophrenia have similar candidate genes for schizophrenia as adults do: DAOA/G30, GAD1, Prodh2/DGCR6, and DISC1. An important gene for adolescent-onset schizophrenia is the catechol-O-methyltransferase gene, a gene that regulates dopamine. There is also some research that shows that children with schizophrenia have an increase in genetic deletions or duplication mutations and some have a specific mutation called 22q11 deletion syndrome, which causes a child to be at a 10-30% likelihood of developing schizophrenia.

Environmental Factors
The environment influences the neurodevelopment of a child and these factors may occur through several different means: neurological damage, gene-environment interactions, epigenetic effects, and de novo mutations. The best-supported environmental exposure that is linked with schizophrenia is in utero maternal famine and paternal age. Major environmental factors for schizophrenia are prenatal and early childhood risks: pregnancy/delivery complications such as hypoxia, toxemia, preeclampsia, and low birth weight, maternal infections during pregnancy such as influenza, respiratory infections, and rubella, maternal stress, and childhood head injury.

Neuroanatomical Differences
MRI studies have found that there are also several small differences between the brains of those with schizophrenia and normal developing brains. These include ventricular enlargement, third ventricle enlargement, hippocampus volume deficits, preferential involvement of medial temporal lobe structures, frontal lobe abnormalities, combination of gray and white matter of superior temporal gyrus, reduced gray matter that decreases with age, parietal lobe abnormalities, and subcortical abnormalities. Specifically, in childhood-onset schizophrenia, there appears to be faster cortical thinning of gray matter in parietal-frontal pattern throughout adolescence that slows down in adulthood. This may be due to excessive pruning or decreased myelination. However, brain differences may be a symptom not a cause of schizophrenia.