Genetic diseases are caused by error in the DNA in sequences called “genes” or is an illness caused by abnormalities in genes or chromosomes. Most cells in the human body have 23 pairs of chromosomes, making a total of 46. There are four different types of genetic disorders: single-gene, multifactorial, chromosomal, and mitochondrial.

A genetic disorder is a disease caused by abnormalities in an individual’s genetic material genome. Genetic disorders can also be inherited. If a person carries the dominant gene for a disease, he or she will usually have the disease and each of the person’s children will have a 1 in 2 (50%) chance of inheriting the gene and getting the disease. Cancers is also caused by a mutation in a gene or group of genes in a person’s cells. These mutations can occur randomly or because of an environmental exposure such as cigarette smoke.

Chromosomes, distinct structures made up of DNA and protein, are located in the nucleus of each cell. Because chromosomes are carriers of genetic material, such abnormalities in chromosome structure as missing or extra copies or gross breaks and rejoining (translocations) can result in disease. Multifactorial, this type is also called as complex or polygenic. This type is caused by a combination of environmental factors and mutations in multiple genes.

According to researches, a child whose parent has schizophrenia has about a 10 percent chances of getting this diseases, while one in general the percentage is about 1 percent. Here’s an excerpt of a detailed discussion at Discovery Health:

Researches have shown that “multiple genes are involved in creating a predisposition to develop the disorder. In addition, factors such as prenatal difficulties like intrauterine starvation or viral infections, perinatal complications, and various nonspecific stressors, seem to influence the development of schizophrenia.”

There’s a lot of research in Schizophrenia, but it is not yet understood how the genetic predisposition is transmitted. Several regions of the human genome are being investigated to identify genes that may confer susceptibility for schizophrenia. The strongest evidence to date leads to chromosomes 13 and 6 but remains unconfirmed. Identification of specific genes involved in the development of schizophrenia will provide important clues into what goes wrong in the brain to produce and sustain the illness and will guide the development of new and better treatments. To learn more about the genetic basis for schizophrenia, the NIMH has established a Schizophrenia Genetics Initiative that is gathering data from a large number of families of people with the illness.