Genetics

Genetics is the study of heredity, the process in which a parent passes certain genes to their children. A person's appearance - height, hair color, skin and eyes - is determined by genes. Other characteristics affected by heredity:

Likelihood of getting certain diseases

Mental abilities

Natural talents

An abnormal trait (anomaly) is passed down through families (inherited) may:

Have no effect on the health or well being of the person (for example, may just involve a white patch of hair or enlarged earlobes).

Be of minor consequence (eg, blindness ).

Have a dramatic effect on the quality or life expectancy of the person.

For most single-gene disorders, genetic counseling is recommended and it is possible that many people also want to seek prenatal diagnosis.

The terms anomaly, abnormality, disorder, defect, disease and syndrome are not used consistently and do not have precise definitions

Human beings have cells with 46 chromosomes - 2 sex chromosomes and 22 pairs of nonsex chromosomes (autosomes). Males are "46, XY" and females "46, XX". Chromosomes are composed of strands of genetic information called DNA.

Genes are sections of DNA and its location is called locus. Most genes carry information that is needed to produce a protein.

The pairs of autosomal chromosomes (one from the mother and one father) carry basically the same information, ie each has the same genes, but there may be slight variations in these genes. These slight differences occur in less than 1% of the DNA sequence and produce variants of a particular gene, called alleles.

If a gene is abnormal, can lead to an abnormal protein or an abnormal amount of a normal protein. Since the autosomal chromosomes are paired, there are 2 copies of each gene, one from each parent. If one of these genes is defective, the other can produce sufficient protein, such that any disease is not observed. This is called a recessive disease and is said that the gene is inherited in a recessive pattern.

However, if only one abnormal gene is needed to produce the disease is called a dominant hereditary disorder.In this case, if an abnormal gene is inherited from the father or mother, the child will likely show the disease.

A person with an abnormal gene is termed heterozygous for that gene. If a child receives an abnormal recessive disease gene from both parents, will show the disease and a child homozygous for that gene.

If two parents each have a copy of a recessive disease gene, then each child has a probability of 25% (1 in 4) to manifest the disease. If one parent has two copies of the disease gene and the other has a copy, then the child has a 50% (1 in 2) chance of being homozygous.

CANCER:

Cancer begins in your cells, which are the building blocks of your body. Normally, your body forms new cells as you need them, replacing old cells that die. Sometimes this process goes wrong. New cells grow even when you don't need them, and old cells don't die when they should. These extra cells can form a mass called a tumor. Tumors can be benign or malignant. Benign tumors aren't cancer while malignant ones are. Cells from malignant tumors can invade nearby tissues. They can also break away and spread to other parts of the body.

Most cancers are named for where they start. For example, lung cancer starts in the lung, and breast cancer starts in the breast. The spread of cancer from one part of the body to another is called metastasis. Symptoms and treatment depend on the cancer type and how advanced it is. Treatment plans may include surgery, radiation and/orchemotherapy.

Cancer is a term used for diseases in which abnormal cells divide without control and can invade other tissues. Cancer cells can spread to other parts of the body by the bloodstream and the lymphatic system .

Cancer is not just one disease but many diseases. There are over 100 different types of cancer. Most cancers are named after the organ or cells where they begin, for example, cancer that begins in the colon is called colon cancer, cancer that begins in basal cells of the skin is called squamous cell baseline.

The types of cancer can be grouped into larger categories. The main categories of cancer are:

Carcinoma: Cancer that begins in the skin or in tissues that line or cover internal organs.

Sarcoma: Cancer that begins in bone, cartilage, fat, muscle, blood vessels or other connective or supportive tissue.

Leukemia: Cancer that begins in the tissue in which blood is formed, such as bone marrow, and causes them to produce large numbers of abnormal blood cells that enter the blood.

Lymphoma and myeloma: cancers that begin in cells of the immune system .

Central nervous system cancers: cancers that begin in the tissues of the brain and spinal cord.  

Origin of cancer

All cancers begin in cells, the basic units of life of the body. To understand what cancer is, it helps to know what happens when normal cells become cancerous. 
The body is formed of many cell types. These cells grow and divide in a controlled manner to produce more cells as needed to keep the body healthy. When cells grow old or get damaged, they die and are replaced by new cells.

However, sometimes this orderly process goes wrong. The genetic material ( DNA ) of a cell may be damaged or altered, resulting in mutations (changes) that affect growth and normal cell division. When this happens, cells do not die when they should and new cells form when the body does not need.Leftover cells form a mass of tissue that is what is called tumor .

characteristics of cancer

Benign tumors: Your name ends with the suffix-oma, simply, and the origin of the tissue from which the benign tumors may be: fibroma (fibrous tissue), myxoma (loose connective tissue), lipoma (fatty tissue), chondroma (cartilage), osteoma (bone tissue), hemangioma (blood vessel), lymphangioma (lymphatic vessels), meningioma (meninges), glomus tumor (supporting nerve tissue), leiomyoma (smooth muscle), rhabdomyoma (striated muscle tissue ), papilloma (epithelial tissue forming buds), adenoma (glandular tissue), teratoma (totipotent cells), nevus (melanocytes)

Some benign tumors derived from epithelial tissue end with the suffix "adenoma" because the original epithelial tissue forms glands, although we must bear in mind that there are many exceptions to the rules of nomenclature tumor. For example: A benign tumor of melanocytes or nevus Nevus is called, and as malignant melanoma.

Malignant tumors or cancer:

Cancers that arise from tissue or mesoderm mensenquimatosos called sarcomas (Greek sarcos, "meaty"), eg fibrosarcoma, myxosarcoma, liposarcoma, chondrosarcoma, osteosarcoma, angiosarcoma, lifangiosarcoma, sinoviosarcoma, leiomyosarcoma, rhabdomyosarcoma.

Malignant neoplasms of epithelial origin, arising from any of the three germ layers of the embryo are called carcinomas, eg squamous cell carcinoma or squamous cell, basal cell carcinoma, adenocarcinoma, cystadenocarcinoma, choriocarcinoma, carcinoma of the penis.

The tumors arising from nerve tissue are gliomas (actually it's not a tumor derived from nerve cells, but one of the cell types responsible for their support, glial cells, tissue "connective" of the brain, so to speak .)

Hematologic cancers are lymphomas and leukemias, always malignant (derived from myeloid and lymphoid tissue, respectively).

 

Malignant tumors that do not meet the above rules and ending-oma, are: melanoma, hepatoma, seminoma. There are also the mesothelioma, which originates in the serous membranes (pleura, pericardium, peritoneum), and can be epithelial or mesenchymal

Cancer detection

 

Early detection and prompt treatment are directly responsible for the increased survival rates.

The tools for the detection of cancer include:

Self-exams

Biopsy (the removal of living tissue for the purpose of microscopic examination of cells)

Ultrasound (using sound waves reflected high frequency to differentiate various tissue types)

Computed tomography (CT) (the use of x-rays to produce a photo section of the body parts)

Magnetic resonance imaging (MRI) (the use of magnetic fields and radio waves to show changes in soft tissues without the use of x-rays).

Detection of cancer in children

Cancers in children are often difficult to detect. Parents should strive to attend with their children to regular medical examinations and should be alert to any unusual signs or symptoms persistent.It is important to tell your doctor about any unusual signs or symptoms.

Unusual signs or symptoms include:

Strange mass or swelling

Unexplained paleness

Loss of energy

Trend suddenly bruising

Persistent pain or lameness, localized

Fever or prolonged illness, unexplained

Frequent headaches, perhaps with vomiting

Sudden changes in vision or eye

Excessive and rapid loss of weight.

CANCER TREATMENTS: SURGERY, RADIOTHERAPY, CHEMOTHERAPY AND MARROW TRANSPLANTATION

Surgery is the method used for small tumors located in a particular place. To be fully effective it requires removal of the tissue surrounding the tumor so as to ensure that all cancer cells have been removed. 

If the cancer has spread to other areas, through the blood or lymph, there shall be other treatments, either surgery or added to the unique and different to her. 

The therapy uses high-energy particles can penetrate the body. Using a machine called a linear accelerator, generate and direct the particles to the particular place where you have to apply. Other areas of the body are protected to not receive radiation. 

Radiation therapy uses particles similar to X-rays, which are used to make a radiograph, what happens is that the latter, the quantity supplied is very small. 

Cancer cells are especially sensitive to the radiation. 
The pathologist will decide the exact area where rays provide. The exact area of ​​the tumor will have been located through diagnostic tests like X-rays, biopsies, etc.

Radiation therapy can be used as monotherapy in cases where tumors are particularly sensitive to radiation and no signs of it has spread to anywhere else. 

Can be used as supplementary treatment to surgery, to apply prior to this, and to decrease tumor size and is easier to remove. 

The joint treatment of radiotherapy and chemotherapy is also used frequently.Sometimes, the use of chemotherapy before radiation makes the cancer cells more radiosensitive. Other radiotherapy is used after chemotherapy to ensure removal of all cancer cells. 

The patient will have to go on an outpatient, clinic or hospital where you are given radiotherapy. The duration of each session is about twenty minutes. The patient will be alone in an isolated room so that the radiation does not spread. The areas where you have to apply the radiation will be marked and the other will be protected from radiation. After the session, the patient may leave your casa.La chemotherapy is the use of drugs to treat cancer. They are products whose function is to remove, damage or delay the growth of cancer cells. 

The main issue that causes this treatment is derived from cancer cells are not agents or foreign to the body but are similar to surrounding cells. This makes the drugs, which act primarily against cancer cells, also have effects on normal cells.

* INTERACTIVE GRAPHIC: Radioactivity cancer

The chemotherapy affects cells that divide rapidly, which is what they usually do cancer cells. But there are other cells which are not cancer and also divide rapidly. 
Some chemotherapy drugs work by interrupting the stage where the cancer cell is split and this makes the rise time is greater and the cell dies. 

Other drugs involved in all phases of the cell. Because cancer cells are more fragile than normal, are more affected than normal, so the action of drugs is primarily on them. 

Other drugs change the external conditions of the organism to which they are unfavorable to the cells. This is the case of hormones that can block the action of certain substances and thus not support the growth of malignant cells. 

In recent years, are using combinations of chemotherapeutic agents because it was found that their combined action is more effective to kill cancer. 

Anticancer drugs are usually combined with different modes of action and ability to produce different effects. 

There is treatment that contain a drug involved in a phase of the cell, other involved in another phase and a hormone that changes the conditions external to the cells. 

These combinations are intended to be more effective on cancer cells and less harmful to normal cells. 

Chemotherapeutic drugs may be administered in different ways: through an oral tablet, using a serum or intravenous injection, intramuscular injection or by injection through a needle into the bone marrow. 

Side effects of chemotherapy 

Any drug can cause undesirable side effects due to its action on the body. 

Chemotherapeutic drugs that act on cells that divide frequently, cancer cells do, they can also act on those normal cells also divide frequently. These cells are, for example, cells from bone marrow (where blood cells are produced) and mucous membranes of the gastrointestinal tract. Hair follicles also divide frequently and are sensitive to some chemotherapy drugs. 

For this reason, some of these drugs produce nausea, vomiting, diarrhea, mouth sores. Others give rise to hair loss. The bone is temporarily impaired in its function of producing blood cells. Therefore it is easier for infections to occur, as the number of leukocytes is lower, or fatigue or anemia occurs because the number of red blood cells may also decrease.

 Being very strong medications, side effects are too. Due to its side effects, chemotherapy is given in cycles, during a period of time the drugs are administered and then allowed a period of rest. 

This rest period is used to produce haematological recovery since, as noted above, these drugs have effects on cancer cells and others that are not. 

Side effects depend on the type of medication is administered, the duration of treatment and overall condition. 

These effects are limited and temporary. 

There are medications that lessen the side effects of chemotherapy such as antiemetics that might diminish or do away with the feeling of nausea. 

Together with chemotherapy, these drugs are administered to reduce or remove, as far as possible, many of these side effects.

* INTERACTIVE GRAPHIC: How does chemotherapy

Bone marrow transplantation is performed when there has been a bone marrow damage that prevents him from performing the functions before chemotherapy was performed. These functions include the formation of blood cells, crucial role in human life. 

Chemotherapy is given to kill cancer cells but at the same time, can damage the bone marrow and other organs. For this reason are generally not used very high doses. 

When cancer does not disappear with a moderate dose of chemotherapy and is required for healing, to administer a much larger, combined with the use of radiation therapy sometimes be necessary to perform a bone marrow transplant because it will be destroyed by chemotherapy . 

The administration of chemotherapy prior to transplantation, it is called conditioning. 

This transplant is administered stem cells that are producing the blood-forming cells. 

Stem cells can be obtained directly from bone marrow or peripheral blood. 

By removing the bone, we must make multiple aspirations in the hip bones (iliac crests) under general anesthesia. 

In bone marrow there is a stem cell per 2,000 cells, for a sufficient number of stem cells must be extracted almost a liter of marrow, which is why you have to make multiple punctures and the patient must be anesthetized. 

Another method is to use cytokines, which are a kind of "bone marrow hormones" that make the stem cells leave the blood stream and are collected with cell separators using a procedure called apheresis or leukapheresis through a similar machine to dialysis. 

Once removed, placed in a transfusion bag to administer to the patient intravenously compatible or freezes at -200 ° C, in the case of autologous transplantation. 

When the bone is inserted inside the bloodstream through a central line, these stem cells are directed towards the bone cavities where implanted, mature and multiply. Thus the patient can again produce healthy blood cells. 

Sometimes this procedure is the only possibility of cure for some patients with leukemia or other diseases such as aplastic anemia, multiple myeloma, lymphoma, thalassemia major, and so on.

There are two types of stem cell transplantation, the allogeneic and autological. 

There is talk of allogeneic when cells are transplanted, either bone marrow or peripheral blood from a donor are family or not, whose tissue type is almost identical to the patient. 

Autologous bone marrow is obtained from the patient, while the disease is in remission, to keep it frozen and perform the transplant patient after applying a high dose of chemotherapy. 

This type of transplant is performed when there is a potential donor or is considered that the risk is very high with allogeneic transplant, the possible rejection that may occur to the patient. 

If you have a twin, the chances of finding a compatible donor has not exceeded 35%. 

The autologous transplant is less risky than the absence of the allogeneic rejection. However, there is a higher recurrence rate because it is possible to extract the marrow from the patient be any cancer cells that occur after transplant recurrence. 

Once that has been made transplantation, marrow reconstitution takes 3-4 weeks. During this period, called aplasia, the patient does not have a sufficient number of blood cells to stay alive. Because of this, the risk of infection or bleeding is high, so it must remain in the hospital for transfusions, antibiotics or treatments to stimulate the growth of granulocytes.

 

hereditary Diseases

Inherited diseases are genetic diseases that set whose main characteristic is its survival for generations, passed down from father to son and so on.

Monogenic inherited diseases are those caused by the mutation or alteration in the DNA sequence of a single gene. Also called Mendelian inherited diseases, for airing on the offspring according to Mendel's laws. There are more than 6,000 monogenic inherited diseases with a prevalence of one per 200 births. Still, unless you are polygenic diseases.

Monogenic diseases are transmitted according to Mendelian inheritance patterns such as:

Autosomal recessive disease. For the disease to manifest, you need two copies of the mutated gene in the genome of the affected person, whose parents usually do not have the disease, but each carry one copy of the mutated gene, so it can pass on to offspring. It is transmitted by non-sex chromosomes (autosomes). The chance of having a child affected by an autosomal recessive between two people carrying a single copy of the mutated gene (which do not manifest the disease) is 25% ..

Autosomal dominant. You just need a copy of the gene so that the person is affected by an autosomal dominant. Normally one of the parents of an affected person has the disease and these parents have a 50% chance of passing the mutated gene to their offspring, who get the disease.

X-linked disease The mutated gene is located on chromosome X. These diseases can be transmitted in turn in a dominant or recessive.

multifactorial diseases

Polygenic also called, are produced by the combination of environmental factors and multiple mutations in multiple genes, usually from different chromosomes. Not follow a Mendelian inheritance pattern, and sometimes when it is a major gene responsible for the disease behaves as dominant inheritance with incomplete penetrance, as in the case of hereditary breast cancer (BRCA1 and BRCA2 genes). Some of the most common chronic diseases are polygenic, for example, hypertension, Alzheimer's disease, schizophrenia, retinitis pigmentosa, asthma, diabetes mellitus, various cancers, including obesity. Polygenic inheritance is also associated with heritable traits such as fingerprint patterns, height, eye color and skin color. Possibly the most diseases are multifactorial diseases caused by the combination of genetic disorders that predispose to a particular susceptibility to environmental agents

Family tree

A family tree is a graph that lists the ancestors and descendants of an individual in an organized and systematic in the form of tree or table. Can be upward, exposing the ancestors or ancestors of a person, or down, exposing all descendants. To make a family tree is necessary first to have conducted a genealogical or pedigree of the individual.

Depending on the purpose or use other choice given to the family tree, it can refer only to male filiation and succession, also called bloodline or lineage, or parentage and female succession, also called the navel line.

The family tree does not apply only in humans and is also used to show the pedigree of an animal, to represent the evolution of a language or language, follow the path of a political party, an art form or a martial art and see the ramifications