Fingers point to genes in the case of hereditary diseases, but they are not the only ones responsible for them. Often, environmental and lifestyle influences play an important role.

Professor Andreas Fischer of the German Center for Neurology in Göttingen explained that hereditary disease means a change in the genetic structure, in other words, a mutation, which in turn leads to cell dysfunction.

Professor Andreas Fritsche prefers to talk about hereditary predisposition rather than hereditary disease. The vice president of the Institute for Diabetes Research in the German city of Tubingen said that genetic disease is often a must.

Two types of genetic diseases
Prof. Peter Lechter, head of molecular genetics at the German Center for Cancer Research in Heidelberg, said that two types of genetic diseases are medically differentiated: one with only one gene and one with more than one gene in so-called complex genetic diseases.

Lichter explained that in the first type increases the chances of infection by a large proportion, while the situation in the second type; where each gene has only a small effect, pointing out that most common diseases such as diabetes, Alzheimer's, cancer and cardiovascular diseases fall under the second type.

Lifestyle
In most cases, genes are not only the cause of disease, but environmental and lifestyle effects also play an important role. In Alzheimer's, for example, other factors raise the risk of the disease, such as weight gain, diabetes or high cholesterol, as well as genetic changes. .

Lichter added that in 5% of cases, cancer is due to genetic factors. If breast cancer appears in two consecutive generations, ie with the mother and daughter, there is a high risk of hereditary family transmission. But, on the other hand, there is no link between a father's prostate cancer and his daughter's breast cancer.

There are about 300 genetic changes that cause type 2 diabetes, the most common form, with more than 95 percent of all people with diabetes, Fritsche said. If the mother or father develops type 2 diabetes, half of their children may develop the same disease.

Fritsche stressed that the genetic factor should combine with lifestyle and environment; lack of movement and unhealthy nutrition raise the risk of developing type 2 diabetes.

Type 1 diabetes occurs in families where there is no person with diabetes, and genetics occurs much less here.

The question arises: what should be done if there is a genetic predisposition? Fischer replied that in such a case tests should be conducted to determine the extent of the genetic risk, knowing that the early diagnosis of the disease raises the chances of treatment.