Genetic Disorders

Genetic Disorders Four types of genetic disorders Single gene: disorders caused by the abnormality or mutation in the sequence of one gene Multifactorial: caused by a combination of environmental factors and mutation in multiple genes Chromosomal: Abnormalities in chromosomal structure such as missing chromosomes or extra copies Mitochondrial: caused by a mutation in the non-chromosomal DNA of the mitochondria

Mutation A mutation is any random change in the amount or structure of genetic material (DNA) can be harmful, helpful, or have no impact happen because of random changes during cell division (meiosis/mitosis)

Single Gene Mutation A Gene Mutation is a change that affects a specific gene on a chromosome the DNA sequence is altered, resulting in a different trait

Single Gene Mutation Sickle Cell Anemia An abnormality of the hemoglobin (oxygen carrying protein in the blood) that leads to them being sickle-shaped A sufferer of sickle cell carries two copies of the recessive sickle cell gene, located on chromosome 11 Health problems may include pain, swelling in hands and feet, or anemia (reduced red blood cells or ability to carry oxygen) Affects 4.4 million people worldwide

Single Gene Mutation Cystic Fibrosis An autosomal recessive disorder in which normally thin secretions such as sweat, digestive fluid, and mucus become thick The disorder affects mostly the lungs but also the pancreas, liver, kidneys and intestine. Long term issues include difficulty breathing and lung infections About I in 25 people is a carrier while the disorder affects 1 in 3000

Single Gene Mutation Hemophilia a mutation of a gene that causes a deficiency of a blood clotting protein resulting in abnormal bleeding Sex-linked disorder with gene for hemophilia on the X chromosome Affects 1 in 10000 people

Chromosomal Mutation Genetic disorders may be passed down from parents (heredity) or they may be caused by new mutations or changes to the DNA A change involving either part of, or all of, a chromosome Caused by problems during meiosis such that gametes have abnormal chromosomes This results in the offspring inheriting a change in genetic material and different traits

Chromosomal Mutation Nondisjunction The addition or loss of a whole chromosomes Errors in the segregation of chromosomes during meiosis resulting in the presence of an abnormal number of chromosomes in a cell the leading known causes of miscarriage and the most frequent cause of developmental disabilities.

Chromosomal Mutation

Chromosomal Mutation Down Syndrome: trisomy of the 21st chromosome (5.4 million world-wide) Physical growth delays Mild to moderate intellectual disabilities Characteristic facial features

Chromosomal Mutation Turner Syndrome: only one X 23rd chromosome resulting in a female with underdeveloped sexual characteristics (1 in 2000-5000) Visual impairments and learning disabilities Webbed neck, broad chest, and short stature Underdeveloped ovaries resulting in infertility

Chromosomal Mutation Klinefelter Syndrome: XXY 23rd chromosome resulting in a male with underdeveloped sexual characteristics (1 in 500-1000) Learning disabilities Reduced strength, uncoordinated Reduced fertility of infertile

Karyotyping Karyotyping is a test to examine chromosomes in a sample of cells, which can help identify genetic problems as the cause of a disorder or disease in a developing baby. This test can: Count the number of chromosomes in cells Look for structural changes in chromosomes in cells Use this as a diagnosis

Multifactorial Genetic disorders may also be complex, multifactorial, or polygenic, meaning they are likely associated with the effects of multiple genes in combination with lifestyles and environmental factors Multifactorial disorders include heart disease and diabetes There is no clear cut pattern of inheritance due to the complexity of the disorders

Multifactorial Cancer Mutagens, carcinogens, and particular viruses can cause mutations that lead to cancers because they change the internal and external factors that normally control cell division resulting in cancer A mutated cancer cell grows and divides uncontrollably causing tumors to form Tumors that don’t interfere with tissue function are benign (non-cancerous), while those that do interfere with tissue function are called malignant Initial tumor cells can spread and form more malignant tumors in other tissues in the body

Multifactorial Carcinogens Asbestos: Used as ceiling and pipe insulation in older buildings, floor tiles, and fire-resistant fabrics Known to cause cancers of the lungs, digestive tract and the abdominal lining Internal Combustion Engine Exhaust: gas emitted as a product of the combustion of fuels such as natural gas, gasoline, diesel, coal, etc. Known to cause cancers of the lungs and bladder Ultraviolet radiation: electromagnetic radiation present in sunlight (about 10% of sunlight is ultraviolet radiation) While having beneficial effects (promotes production of vitamin D and serotonin), overexposure can damage DNA in the skin cells causing skin cancers melanoma and carcinoma