Sickle cell anemia and other genetic disorders probed. (1981)

developments in science engineering and medicine that help solve the problems of modern life [Music] [Music] within the cells of your body are the genes which determine if you or your children have or transmitted any of thousands of hereditary diseases one such hereditary disease sickle cell anemia affects more than 50,000 North Americans primarily those whose ancestors came from the Middle East Asia southern Europe or Africa [Music] intense research is now underway to better understand manage and treat hereditary diseases this footage has been made available by dr. James E Bowman director of the comprehensive sickle cell center of the University of Chicago this is a rendering of a red blood cell smaller than a needle point there are 23,000 billion red blood cells in your bloodstream carrying oxygen from the lungs to all parts of the body to be used in chemical processes that provide energy [Music] in hereditary sickle-cell disease red blood cells become rigid sickles quite unlike normal flexible blood cells the rigid sickle cells clog up the capillaries preventing fresh blood and oxygen from getting through to the surrounding tissues [Music] this results in pain to one or many parts of the body complications may include painful swelling of the hands and feet [Music] ulcers on the legs bleeding inside the eyes heart failure or stroke there may also be damaged two kidneys liver lungs hips [Music] or spleen [Music] the body's defense mechanism also rids the blood of many of the sickle cells leaving fewer cells to carry oxygen the condition called anemia to understand sickle cell anemia we must look inside the red blood cell within the enclosing cell membrane are about 280 million hemoglobin molecules whose function is to carry oxygen each hemoglobin molecule holds four iron atoms in a framework of heme oxygen molecules stick to the iron atoms one at a time the hemoglobin picks up oxygen when the red cell is in the lungs then the red cell is carried by the blood to the small blood vessels called capillaries throughout the body where the oxygen is released [Music] hemoglobin is a protein like all proteins it's made up of very small molecules called amino acids there are about 20 types of amino acids differing in both shape and chemical properties some of the amino acids are water-soluble which means they will mix with water the same way sugar does when you stir it in a glass of water other amino acids have parts that are oily which means they will not mix with water instead they behave somewhat like oil droplets separating from water and clumping together [Music] any protein is composed of both water-soluble and oily types of amino acids linked together something like a string of beads [Music] and usually surrounded by water proteins fold up so that most of the oily parts are inside away from the water the water-soluble parts are outside in contact with the water a compact ball or globe of protein known as a globin joins with the iron holding em to form hemoglobin each hemoglobin molecule holds four of the proteins because of this folding hemoglobin molecules can mix easily with the water molecules in the red blood cells sickle-cell anemia results from substitution of a water-soluble amino acid glutamate on the outside surface by an oily amino acid called valine the new sickle cell hemoglobin are therefore less soluble in water than normal hemoglobin instead they stick together like clumping oil droplets [Music] clumping is triggered by the release of the oxygen molecules in the capillary the change of shape when this happens also brings the oily amino acids closer together [Music] the oily amino acids on the sickle hemoglobin also line up with the oily regions on neighboring hemoglobins sticking together to form long stacks or rods [Music] the rod like structures distort the cell membrane until it forms the characteristic sickle shape which causes the disease symptoms today there are several ways to reduce the dangers and discomfort of sickle cell disease treatments include pain killing medicine antibodies fluids prompt treatment of complications and occasionally transfusions of red blood cells son with the disease have many symptoms some few some none at all life expectancy is also variable some patients die at an early age but many lead productive lives until an advanced age how is a hereditary disease such as sickle cell anemia passed on and what determines if a particular offspring will have the trait or have the disease itself the hereditary pattern of each individual is located in his genes which are found within the nuclei of the cells on structures known as chromosomes genes are made up of long string light molecules called DNA [Music] genes are passed from parent to offspring via special cells produced in the bodies of adults called germ cells or gametes [Music] there are two kinds of germ cells one from the father and one from the mother each holds only a single set of genes the offspring has two sets of genes one set from each parent it then develops into a child [Music] the DNA of the offspring is formed from the combined DNA codes of both parents variations in this new DNA code determined the offsprings heredity including possible hereditary diseases such as sickle cell anemia [Music] whether the child will carry the hereditary trait or actually exhibit the disease itself depends on whether either or both parents have the trait or the disease [Music] simple tests can now determine if a particular person has sickle cell trait or sickle cell disease the chances of their children having these hereditary conditions depend on the genes of the parents assume both have sickle cell trait one normal gene one sickle cell gene each parent will then have equal amounts of germ cells with and without the sickle gene so there are four possible pairings in the children female s gene two male s gene female s gene two male aging female a gene two male s gene and female aging to male AG so with each birth there is a 1/4 or 25% chance for a child with normal hemoglobin a 2/4 or 50% chance for a child with sickle cell trait and a 1/4 or 25% chance for a child with sickle cell anemia statistical rules have been found which govern various pairings but there is still no way to predict for any particular pairings before conception at best the odds of the different possibilities can be estimated [Music] the distribution of sickle cell hemoglobin corresponds very closely to the distribution of falciparum malaria the deadliest of the malarias it has been proposed that persons with the sickle cell trait have a better chance of surviving falciparum malaria than those with normal hemoglobin this could account for the high frequency of sickle hemoglobin in regions where malaria is prevalent on the other hand persons with sickle cell anemia are severely affected by falciparum malaria [Music] all populations have hereditary diseases for example there is a form of anemia known as thalassemia that affects large numbers of people in parts of Europe the Middle East the Far East the South Pacific and Africa there are other kinds of abnormal hemoglobins affecting populations in Asia and Africa such as hemoglobins C D and E there are also hereditary disorders affecting substances other than hemoglobin tay-sachs disease that is order of the nervous system is found primarily in Jewish populations from Central and Eastern Europe cystic fibrosis a hereditary disease resulting in respiratory infections mainly affects populations in northern Europe the more than 2,000 known hereditary diseases include types of muscular dystrophy hemophilia and some forms of mental illness by seeking a better understanding of hereditary illness today's medical research scientists are working towards ways to manage some of mankind's most widespread and burdensome afflictions lynchburg foundry has been proud to bring you this issue of the science screen report to further your understanding of science engineering medicine and technology [Applause]