Chromosome Mutations

Abbie Cain

Translocation

· Translocation is a mutation in which a large segment of one chromosome breaks off and attaches to another chromosome.

· An example of a Translocation mutation c-myc on chromosome 8, gives the protein symphocyte-proliferative ability.

· A potential genetic disorder caused by translocation mutations would be Burkitt Lymphoma.


Burkitt Lymphoma


· Burkitt lymphoma is a form of non-Hodgkin's lymphoma in which cancer starts in immune cells called B-cells. Recognized as the fastest growing human tumor, Burkitt lymphoma is associated with impaired immunity and is rapidly fatal if left untreated.

· The symptoms of Burkitt lymphoma depend on the type. Most cause tumors, cause loss of appetite, weight loss, fatigue, night sweats, and unexplained fever.

· Treatment for Burkitt Lymphoma include intensive intravenous chemotherapy, autologous stem cell transplantation, radiation therapy, and steroid therapy.

· Ways to diagnose Burkitt Lymphoma include a biopsy, CT imagining of the chest, abdomen, and pelvis, chest x-ray, PET or gallium scan, bone marrow biopsy, exam of spinal fluid, blood tests to measure kidney and liver function, and testing for HIV disease.

Inversion

· Inversion is a chromosomal rearrangement in which a segment of genetic material is broken away from the chromosome, inverted from end to end, and re-inserted into the chromosome at the same breakage site.

· An example of inversion seen in humans is on chromosome 9, at inv(9)(p12q13). This inversion is generally considered to have no harmful effects, but there is some suspicion it could lead to an increased risk for miscarriage or infertility for some affected individuals

· A potential genetic disorder caused by Inversion mutations would be leukemia.


Leukemia


· Leukemia is a cancer of blood cells.

· Symptoms of leukemia include pain in the bones or joints, swollen lymph nodes that usually don’t hurt, fevers or night sweats, feeling weak or tired, bleeding and bruising easily, frequent infections, discomfort or swelling in the abdomen, and weight loss or loss of appetite.

· Treatment for leukemia depends on the type of leukemia. Most patients are treated with chemotherapy, radiation therapy, or bone marrow transplantation.

· Leukemia may be diagnosed by looking into medical history, physical exams to look for signs of leukemia, blood tests, bone marrow biopsy, and chest x-rays.

Deletions

· Deletion is a type of mutation involving the loss of genetic material. It can be small, involving a single missing DNA base pair, or large, involving a piece of a chromosome.

· An example of a deletion would be deletion of the end of the short arm of chromosome 5 (5p—usually paternal) which causes Cri-du-chat.

· A potential genetic disorder caused by deletion would be Cri-du-chat.


Cri-du-Chat


· Cri du chat syndrome - also known as 5p- syndrome and cat cry syndrome - is a rare genetic condition that is caused by the deletion (a missing piece) of genetic material on the small arm (the p arm) of chromosome 5. The cause of this rare chromosomal deletion is unknown.

· Symptoms for Cri-du-chat include high-pitched cat-like cry, mental retardation, delayed development, distinctive facial features, small head size (microcephaly), widely-spaced eyes, low birth weight, and weak muscle tone in infancy.

· No specific treatment is available for this syndrome. Children born with this genetic condition will most likely require ongoing support from a team made up of the parents, therapists, and medical and educational professionals to help the child achieve his or her maximum potential. With early and consistent educational intervention, as well as physical and language therapy, children with cri du chat syndrome are capable of reaching their fullest potential and can lead full and meaningful lives.

· The diagnosis of cri du chat syndrome is generally made in the hospital at birth. A health care provider may note the clinical symptoms associated with the condition. The cat-like cry is the most prominent clinical feature in newborn children and is usually diagnostic for the cri du chat syndrome.

Duplications

· A duplication mutation is a type of mutation in which a portion of a genetic material or a chromosome is duplicated or replicated, resulting in multiple copies of that region.

· For the present we shall consider only adjacent duplications, which can be tandem, as in the example A B C B C D, or reverse, as in A B C C B D.

· A potential genetic disorder caused by duplication is Cat Eye Syndrome


Cat Eye Syndrome


· Cat eye syndrome is caused by a chromosomal abnormality. People with the syndrome often have vertical, cat-like pupils, thereof the name. The syndrome is also associated with other characteristic facial features and multiple malformations, but there is considerable variation both in severity and in clinical presentation.

· Symptoms of Cat Eye Syndrome include vertical pupils, down-slanting palpebral fissures, widely set eyes, strabismus, underdeveloped eyes, sometimes the irises are absent in which case the pupils are dilated and do not react to light.

· Treatment is carried out in close collaboration with an eye clinic. Visually impaired children learn to optimise remaining vision by using visual aids and some may also find it helpful to learn other communication techniques, such as Braille. Surgeries can also be used to help with other symptoms and problems corresponding with Cat Eye Syndrome.

· The diagnosis is confirmed by chromosomal analysis or array CGH, sometimes supplemented by FISH analysis (fluorescent in situ hybridization).

Non-disjunction

· Non-disjunction is the failure of homologous chromosomes or chromatids to segregate during mitosis or meiosis.

· An example of non-disjunction would be failure of a pair of homologous chromosomes to separate in meiosis.

· A potential genetic disorder caused by non-disjunction would be Down syndrome.


Down Syndrome


· Down syndrome is a set of physical and mental traits caused by a gene problem that happens before birth. Children who have Down syndrome tend to have certain features, such as a flat face and a short neck. They also have some degree of intellectual disability.

· Symptoms of Down syndrome include intellectual disability, heart defects, and different physical appearances.

· Treatment for Down syndrome focuses on making sure that your child has regular medical checkups, helping your child develop, watching for early signs of health problems, and finding support.

· A prenatal screening test. This test can show an increased likelihood that a fetus has Down syndrome, but it cannot determine Down syndrome is definitely present. A prenatal diagnostic test. This test can determine with certainty that Down syndrome is present. Diagnostic tests carry a slightly greater risk to the fetus than do screening tests.