Genes and diseases

Christiane Fux studied journalism and psychology in Hamburg. The experienced medical editor has been writing magazine articles, news and factual texts on all conceivable health topics since 2001. In addition to her work for, Christiane Fux is also active in prose. Her first crime novel was published in 2012, and she also writes, designs and publishes her own crime plays.

More posts by Christiane Fux All content is checked by medical journalists.

Genes play a key role in many diseases. Usually it is a whole bundle of risk genes that favor a disease, but sometimes just a single error in the genetic code is enough.

Risk genes

A whole range of risk genes is known for most major diseases thanks to the research zeal of recent years. These include, for example, migraines, heart attacks and Parkinson's, diabetes, obesity, Alzheimer's and multiple sclerosis. But genes are also involved in mental illnesses such as depression and schizophrenia. Since the disease processes are complex, one must assume that not all genes involved are known by a long way.

Often each of the critical gene variants increases the risk of the disease only slightly. Only when several people come together does the risk noticeably increase.

Even if the individual genetic risk for a disease is actually high, the genes are usually not fate: In the vast majority of diseases, environmental factors such as lifestyle also play a decisive role. Even those who are born with a strong disposition for type 2 diabetes, for example, can prevent the outbreak with a healthy diet and exercise.

The young research branch of epigenetics sheds completely new light on the interplay between genes and diseases. He sheds light on the fact that, depending on lifestyle, diseased genes can be switched on or off. Under certain circumstances, the risk genes then have no harmful effect at all.

Diseased genes and chromosomes

Not only humans themselves, but also their genes can become ill. The influence of radiation and certain chemicals can lead to errors in the genetic code. Sometimes these disorders can affect entire sections of the chromosome. Errors also occur time and again with the infinite number of cell divisions that the body's cells make. In the best case, minor damage will be repaired or remain without consequences. But they can also trigger diseases such as cancer.

Hereditary diseases

Hereditary diseases are rare. They are passed on from parents to their offspring. Often it is a single diseased gene. Fortunately, these hereditary diseases are predominantly recessive, that is, if only one of the two corresponding chromosomes carries the diseased gene, the disease does not break out. The disease only affects the child if both parents are carriers and pass the diseased gene on. These include, for example, cystic fibrosis and hemophilia.

If a hereditary disease is dominant, a single diseased gene is sufficient. These include, for example, Huntigton's chorea and sickle cell anemia.

If the gene on the X chromosome is inherited, men get sick far more often than women because they do not have a healthy X chromosome to compensate for it. This applies, for example, to hemophilia and red-green blindness.

Genomic disorders

Strictly speaking, congenital diseases based on genomic disorders are not hereditary diseases. Such errors occur, for example, in the production of germ cells, in which a cell with a double set of chromosomes may divide into an egg or sperm cell with a single set (meiosis). An example of this is trisomy 21, in which children have three instead of two of chromosome 21 in their cells. Chromosome defects can also arise when the chromosomes in the germ cells are damaged by environmental toxins or radiation.