Cell mutations occur constantly, but most of them do not lead to any significant changes in the body. However, those that occur in germ cells (called generative) may be inherited. The range of manifestations of mutations is very wide: from subtle or mild, such as changing hair color or shape of the nose, to severe illnesses or birth defects.
The variation of mutations can be divided into chromosome and gene. The latter include the restructuring of
sequence of nucleotide bases in a gene replacement of some other reason, the addition or deletion of one or more bases. Typically, they affect the function of only one gene. Manifestations of chromosome mutations involving several genes, much larger.
Human gene mutations lead to changes in the synthesis of a specific enzyme, which is controlled by the gene. Manifestation of the change depends on the role of this enzyme in the body. If he participates in the growth process, such a mutation can cause growth disturbances, and if involved in the process of digestion, digestive disorders arise, and so on.
However, almost all the genes of the human body are connected in pairs, and the production of enzymes, even in the presence of the mutant gene can be determined by a given pair of normal. The abnormal gene in this case is recessive, and that mutation manifested, both genes must be a pair of mutant, which means it must be present in both parents. Mutant genes that suppress the action of the normal is called dominant, and to manifest their influence is enough presence in one pair.
Caused by chromosomal mutations in hereditary diseases occur in about 1% of newborns. They are the cause of miscarriages and birth of dead children. The most well-known disease of this kind – Down syndrome.
Causes of mutations is not fully known. But many scientists can confidently say that this is the result of external influences, disrupting the molecular structure of DNA, such as radiation and certain chemicals. Frequency certain mutations significantly increased with age of parents, although the reason for this is not entirely clear. It should be noted that the doses of X-rays, which most people get in their entire lives, are not sufficient to markedly increase the mutation rate. However, in medical research, a special precautions to prevent exposure of germ cells.
Control gene mutations are unfortunately almost impossible, however, can be minimized by applying the advice and the advice of a physician-geneticist.