Genetic Diseases - Genetic Testing, Muscular Dystrophy, Huntington's Disease, Cystic Fibrosis, Sickle Cell Disease
recessive genes trait pair
Even at birth the whole individual is destined to die, and perhaps his organic disposition may already contain the indication of what he is to die
—Sigmund Freud, 1924
Genetics, the study of biologic inheritance, explains how and why certain traits, such as hair color and blood types, run in families. Each individual develops from a single fertilized egg, which contains all the information necessary for the development of innate mental and physical characteristics. This information is
carried in twenty-three pairs of rod-shaped chromosomes (containing thousands of genes) that are responsible for determining and transmitting hereditary characteristics. Each pair of chromosomes includes one inherited from the mother and one from the father.
Genes determine specific physical features, such as height and the color of skin, hair, and eyes. Genes also direct the production of cell proteins needed for health and development. There are two types of genes—dominant and recessive. If one gene in a pair is dominant, the trait it carries is strong enough to cancel out the
trait carried by the recessive gene from the other parent. For a recessive gene to appear in offspring, the gene that carries it must be inherited from both parents.
The most common form of genetic testing is screening of newborn infants for genetic abnormalities. In the United States, according to a 2003 report by the General Accounting Office (GAO), about four million newborns per year are screened by testing blood obtained from a prick of the newborn's heel within the first few days of
life. Specific genetic disorders such as phenylketonuria (PKU) an…
Muscular dystrophy (MD) is a term that applies to a group of hereditary muscle-destroying disorders. According to the Muscular Dystrophy Association in 2004, some type of MD affects approximately one million Americans. Each variant of the disease is caused by defects in the genes that play important roles in the growth and
development of muscles. In MD, the proteins produced by the defective genes…
Huntington's disease (HD), or Huntington's chorea, is an inherited, progressive brain disorder. It causes the degeneration of cells in the basal ganglia, a pair of nerve clusters deep in the brain that affect both the body and the mind. HD is caused by a single dominant gene that affects both men and women of all races and
ethnic groups. It does not usually strike until mid-adulthood…
CF is the most common inherited fatal disease among children and young adults in the United States. It occurs most commonly in white people (in one of every 3,200 births of white children and in one in 3,900 of all Americans), and there are approximately 30,000 young people who have the disease; their median (half above and
half below) life span is 33.4 years. However, as more medical advances are…
Sickle cell disease (SCD) is a group of hereditary diseases, including sickle cell anemia and sickle Bthalassemia, in which the red blood cells contain an abnormal hemoglobin, termed hemoglobin S. Hemoglobin S is responsible for the premature destruction of red blood cells, or hemolysis. In addition, it causes the red cells to
become deformed, actually taking on a sickle shape, particularly in par…
TSD is a fatal genetic disorder in children that causes the progressive destruction of the central nervous system. It is caused by the absence of an important enzyme called hexosaminidase A (hex-A). Without hex-A, a fatty substance builds up abnormally in the cells, particularly the brain's nerve cells. Eventually, these cells
degenerate and die. This destructive process begins early in the…
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