Heredity
It may seem strange at first sight, but there are some diseases and illnesses that are not caused by the ecological situation, bad weather, infection or any other types of external sources. Some of the existing diseases are caused by hereditary pathology.
10 percent of all human diseases are caused by pathologic genes or genes that condition the human predisposition to hereditary illnesses.
The mutation processes in human body, as well as in other living organisms lead to the creation of alleles that influence the human health. The absolute majority of chromosome mutations eventually lead to one or another form of pathology. Another group of hereditary diseases is caused by genes whose function depends on unfavorable influence of the environment, for example gout. The unfavorable external condition in this case is improper feeding. There are also illnesses caused by hereditary predisposition (essential hypertension, gastric ulcer, many forms of malignant tumors).
Hereditary diseases or genetic diseases are the malfunctions that are caused by certain changes (mutations) of mainly chromosomes and genes, this means there are two groups of chromosome and hereditary proper (genetic) diseases. Unlike so called congenital diseases that become apparent from the day of birth of a human, hereditary diseases can appear many years later. There are over two thousands of hereditary diseases and syndromes, many of which are the reason of the high level of infant mortality in the world.