Transcript Chapter 2
Chapter Two Your Family Health History © 2011 McGraw-Hill Higher Education. All rights reserved. Creating a Family Health Tree • Also called a genogram or genetic pedigree • Visual representation of your family’s genetic history • Illustrates the patterns of health and illness within a family • Pinpoints areas of special concern or risk for you 2 Sample Family Health Tree 3 What can you learn from your family health tree? • An early onset of disease is more likely to have a genetic component • The appearance of a disease in multiple individuals on the same side of the family is more likely to have a genetic correlation 4 What else can you learn from your family health tree? • A family member with multiple cancers represents a greater likelihood of a genetic association • The presence of disease in family members who have good health habits is more suggestive of a genetic cause than is disease in members with poor health habits 5 You and Your Genes: The Basics of Heredity • The nucleus of every human cell contains an entire set of genetic instructions stored in our DNA (deoxyribonucleic acid) • DNA has four building blocks that can be arranged to form a distinct message (gene) that acts as the body’s instruction booklet • Within the cell’s nucleus, DNA is divided into 23 pairs of chromosomes (one set of each pair comes from each parent) 6 Chromosomes, Genes, and DNA 7 The Human Genome Project • Launched in 1990 • An international collaboration between 20 groups in 6 countries • In April 2003, it was announced that the sequencing of the human genome was complete 8 The Human Genome Project Discoveries • Humans have only 20,000 to 25,000 genes (same as a mouse) • Found many potential applications in medicine and pharmaceuticals • Helped confirm that race has more to do with social and cultural interactions and has no biological basis 9 The Role of Mutations • A change in a gene is called a mutation • Alternate forms of the same gene are called alleles • Some mutations are harmful, other mutations can be beneficial, and some have no effect • Mutations allow for human diversity 10 Genetic Inheritance • Alternate forms of genes, called alleles, are responsible for traits such as eye color • Alleles can be dominant or recessive • Most characteristics (such as height or skin color) are determined by the interaction of multiple genes at multiple sites of different chromosomes 11 Single-Gene Disorders • Some diseases are caused by the alteration (mutation) of a single gene • Autosomal dominant disorder: Mutated gene is on a dominant autosome • Autosomal recessive disorder: Two copies of a mutated gene on an autosome • Sex-linked disorder: Mutated gene is on the sex chromosome 12 Multifactorial Disorders • Many diseases and traits can result from interactions between genes and the external environment • Account for the majority of illnesses and death in the developed world • Heart disease is one example of a multifactorial disease 13 Multifactorial Inheritance in Personality and Behavior • Genes appear to play a role in personality and everyday behavior • Differing personality traits, sexual orientations, and inclination towards addiction may be caused by genetic differences 14 Chromosomal Disorders • An inherited disorder caused by the addition, loss, or alteration of an entire chromosome • May lead to fetal death or death within the first year of life • Individuals may exhibit a broad range of symptoms, called a syndrome, ranging from characteristic physical traits to developmental delays to growth abnormalities • Down Syndrome is an example of such a disorder 15 Genetic Counseling and Testing • • Genetic counseling helps individuals and families understand genetics, evaluate risks, learn about diagnostic tests, and discuss treatment options Popular tests include: – – – – – Diagnostic Predictive Carrier Prenatal Screening Newborn Screening 16 Management and Treatment of Genetic Conditions Treatments may include: • Dietary Modification • Medication • Environmental Adaptation • Gene Therapy 17 Implications of Genetic Research • Controversial issues in genetic screening and testing • Issues of privacy and discrimination • Workplace discrimination • Health insurance discrimination • Eugenics (selective breeding) 18