Система Orphus

Symptoms of disease - violation of chromosomal

In 1962, once in the textbooks for over 30 years, it was argued that human cells contain 48 chromosomes, Joe hin Ist and albert Levan, raising the culture of these cells in the laboratory, found in them only 23 pairs, i.e. 46 chromosomes. This fact is extremely important for the understanding of such chromosomal diseases like down's syndrome, in which each cell is located on 47 chromosomes.

Most of the information about the chromosomal rearrangements, causing phenotypic or bodily changes and anomalies have been received as a result of the research of the genotype (the location of genes in the chromosomes of the salivary glands) of the common fruit fly Drosophila melanogaster, although the same adjustment, apparently occur in the cells of humans and other organisms. In spite of the fact that many human diseases have a genetic nature, only in respect of a small part of it is authentically known, that they are caused by chromosomal abnormalities. Only from observations of the phenotypic manifestations we can conclude that there are those or other changes of genes and chromosomes.

Chromosome - is organized in the form of a double helix molecule of deoxyribonucleic acid (DNA), forming the chemical basis of heredity. It is believed that chromosomal abnormalities arise as a result of restructuring of the order or the number of genes in the chromosomes. Genes are a group of atoms within the molecule of DNA. As is known, DNA molecules determine the nature of the molecules of ribonucleic acid (RNA), which perform the function of «deliverymen» genetic information, which defines the structure and function of organic tissue. This primary genetic substance DNA, acting through the cytoplasm, acting as a catalyst in changing the properties of the cells forming the skin and muscles, nerves and blood vessels, bones and connective tissue, as well as other specialized cells, but not allowing changes of genes themselves in the process. In almost all stages of the construction of organism employing multiple genes, and therefore does not require that each of the physical sign of been the result of the actions of one gene.

Which diseases there is violation of chromosomal

A variety of chromosomal abnormalities may be the result of the following structural and quantitative violations:

The gap chromosomes. Chromosomal of reorganization may be invoked under the influence of x-ray, ionizing radiation, perhaps cosmic rays, as well as many other, yet unknown to us, biochemical or environmental factors.
X-rays can cause rupture of the chromosomes; in the process of restructuring of the segment or segments, come from one chromosome, may be lost as a result of which a mutation or phenotypic change. So, for example, now it is possible the expression of a recessive gene that causes a defect or abnormality, because a normal alleles (gene in a pair of homologous chromosome) is lost and therefore cannot neutralize the impact of the defective gene. In those cases, when chromosomal lack of a human embryo have a lethal effect, " the child is most often die before birth, so that lethal genes do not have an adverse effect on the evolution of the species.

Crossover. A pair of homologous chromosomes are twisted in a spiral like a rain worms during mating and can rupture in any homologous points (i.e., at one level, forming a pair of chromosomes). In the process of meiosis (the division that takes place during the formation of gametes, or reproductive cells egg and sperm) there is a division of each pair of chromosomes, so that only one chromosome from each pair is formed in the egg or spermatozoon. When there is a gap, the end of one chromosome may connects with detached the end of another chromosome, and the two remaining pieces of chromosomes linked together. The result is the formation of two completely new and different chromosomes. This process is called crossing-over.

Duplication or lack of genes. When duplication plot of one chromosome is torn and attached to, etc. homologous chromosome doubling existing in the group of genes. The acquisition of chromosome additional groups of genes is usually causes less harm than the loss of other genes linked. Besides, when the favorable outcome of duplication lead to the formation of a hereditary combination. The chromosome with the lost terminal area (and the lack of localized in its genes) may cause mutations or phenotypic changes.

Translocation. Segments of one chromosome are transferred to another, nonhomologous her chromosome, causing sterility of the individual. In this case, any negative phenotypic manifestation of, at least, may not be passed on to succeeding generations.

Inversion. Chromosome is torn in two or more locations, and its segments inverted (rotated 180 degrees) before you connect in the same order in a reconstructed chromosome. This is the most common and most important way to rearrangements of genes in the evolution of species. However, the new hybrid can be maverick, because detects sterility when crossed with the original form.

The effect of the provisions. In the cases of changing the position of the gene in the same chromosome in the organisms can be found phenotypic changes.

Polyploidy. Failures in the process of meiosis (chromosomal the division in the course of preparation for reproduction), which then would be revealed in germ-cell, can double the normal number of chromosomes in the gametes (sperm or ovum).

Triploids have three complete sets of chromosomes in gametes instead of just mentioned twice. And duplication without disjunction in mitosis (normal cell division) lead to the creation of tetraploid cells with four homologous chromosomes of each species instead of two. Generally speaking, polyploid cells are present in our liver and some other organs, usually without causing any noticeable damage. When the polyploidy manifests itself in the presence of the one and only «extra» chromosome, the emergence of the last in the genotype may lead to serious phenotypic changes. Among them is the down syndrome (down's syndrome, or «mongolism»), in which each cell contains extra 21st chromosome.

Among children with diabetes occurs small percentage of births with complications, in which this additional autosome (asexual chromosome) becomes the reason for the lack of height and weight of the newborn and delay subsequent physical and mental development. Victims of down syndrome have 47 chromosomes. Moreover, an additional 47-I chromosome causes they have excess synthesis of an enzyme that destroys irreplaceable amino acid tryptophan, which is found in milk and milk is necessary for the normal functioning of brain cells and the regulation of sleep. Only a small percent of births with down syndrome, the disease definitely hereditary nature; besides, it is possible prenatal diagnostics her method of amniocentesis.

Which doctor should I contact if there is a violation of chromosomal

  • Geneticist

Are you experiencing violation of chromosomal? You want to know more detailed information, or you need an inspection? Please sign up on reception to the doctor! Doctors will examine you, examine the external signs and help to determine the disease the symptoms, they will consult you and provide the necessary assistance. You can also call the doctor on the house.

Do you feel disrupted chromosomal? You should be very careful approach to your health in general. People pay not enough attention to the symptoms of the disease and don't realize that these diseases can be critically dangerous. There are many diseases that in the beginning didn't manifest in our body, but in the end it turns out, unfortunately, it have already been treated too late. Every disease has its own specific features typical symptoms - called symptoms of the disease. Definition of symptoms is the first step in the diagnosis of diseases in general. You just need a few times a year to be screened by a doctor, not only to prevent a terrible disease, but also to maintain a healthy spirit in a body and the organism in general.

Disorders by category

Disorders by alphabet

Map of the symptoms and the types of disorders is intended solely for educational purposes. We strongly recommend do NOT self-medicate; on all matters relating to the definition of the disease and ways of its treatment, contact your doctor. Md-tips is not responsible for the consequences of use information posted on the site.