© 2007 McGraw-Hill Higher Education. All rights reserved. Chapter 2 Genetics: You and Your Family Health History

© 2007 McGraw-Hill Higher Education. All rights reserved. Genetic Pedigree Also known as a genogram or family health tree A visual representation of your family’s genetic history A diagram that illustrates the patterns of health and illness within a family

© 2007 McGraw-Hill Higher Education. All rights reserved. What can you learn from your genetic pedigree? 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 relationship

© 2007 McGraw-Hill Higher Education. All rights reserved. What else can you learn from your genetic pedigree? 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 link than those members who have disease due to poor health habits

© 2007 McGraw-Hill Higher Education. All rights reserved. The basics of heredity The nucleus of every human cell contains 23 pairs of chromosomes that make up the human genome Chromosomes are made up of tightly coiled molecules of DNA Deoxyribonucleic Acid (DNA) is the genetic material passed from one generation to the next Genes, the units of heredity, are the segments of DNA that encode a protein

© 2007 McGraw-Hill Higher Education. All rights reserved. The Human Genome Project Launched in 1990 An international collaboration of 20 groups in 6 countries April 2003: announced that the sequencing of the human genome was complete

© 2007 McGraw-Hill Higher Education. All rights reserved. The Human Genome Project discoveries Humans have only 20,000 to 25,000 genes (same as a mouse) 2% of human DNA occurs in genes Confirmed that there are no separate biological races in the human species

© 2007 McGraw-Hill Higher Education. All rights reserved. How do genes affect your health? Alternate forms of genes called alleles are responsible for different traits such as eye color Alleles can be dominant or recessive A person can inherit two dominant alleles, one dominant and one recessive allele, or two recessive alleles

© 2007 McGraw-Hill Higher Education. All rights reserved. Genetic mutations Many alleles arise because of mutations that occur during meiosis A mutation is an alteration in the DNA sequence of a gene Mutations can be neutral, beneficial, or harmful to an organism and can cause a disease or disorder

© 2007 McGraw-Hill Higher Education. All rights reserved. Single-Gene Disorders Single-gene disorders are diseases caused by a mutation within one gene Autosomal dominant disorder: mutated gene is an autosome that is dominant Autosomal recessive disorder: two copies of a mutated gene on an autosome Sex-linked disorder: mutated gene is on the sex chromosome

© 2007 McGraw-Hill Higher Education. All rights reserved. Polygenic and Multifactorial Disorders Polygenic disorders are caused by interactions among mutations in multiple genes Multifactorial disorders occur as a result of Interactions of genes with environmental factors such as tobacco smoke, pollution, and diet Multifactorial disorders include heart disease, cancer, diabetes, and schizophrenia

© 2007 McGraw-Hill Higher Education. All rights reserved. Chromosomal Disorders An inherited disorder caused by mutations involving an entire chromosome Many of these disorders lead to fetal death or death within the first year of life Individuals with chromosomal disorders exhibit a broad range of symptoms, called a syndrome, ranging from physical traits to developmental delays Down Syndrome and Turner Syndrome are examples of such disorders

© 2007 McGraw-Hill Higher Education. All rights reserved. Ethnicity and Genetic Disorders Some genetic patterns occur more frequently in particular groups than in others Geneticists have confirmed that closely knit populations, such as ethnic groups, share genes The following are types of inherited disorders that occur more frequently within certain ethnic groups Sickle Cell Disease – affecting people of African decent Tay-Sachs Disease – affecting people of Eastern European Jewish ancestry Cystic Fibrosis – affecting white people of European decent

© 2007 McGraw-Hill Higher Education. All rights reserved. Genetics and Mental Disorders Scientific evidence has suggested that a genetic contribution exists with the following mental disorders: –Schizophrenia –Mood and Anxiety Disorders –Alzheimer’s Disease

© 2007 McGraw-Hill Higher Education. All rights reserved. Genetics and Behavior Researchers are studying the genetic contribution to a variety of behaviors such as: –Personality –Sexual orientation –Addiction

© 2007 McGraw-Hill Higher Education. All rights reserved. Genetic Counseling and Testing The goal of genetic counseling is to help families/individuals understand the role genetics play in a particular disorder The more popular types of tests are listed below: –Diagnostic Tests –Predictive Tests –Carrier Tests –Prenatal Screening –Newborn Screening

© 2007 McGraw-Hill Higher Education. All rights reserved. Management and Treatment of Genetic Conditions Dietary Modifications Medications Environmental Adaptations Gene Therapy

© 2007 McGraw-Hill Higher Education. All rights reserved. Implications of Genetic Research Medical advances and cures Issues in genetic screening and testing Issues of privacy and discrimination Workplace discrimination Health Insurance discrimination Parental eugenics (selective breeding)

© 2007 McGraw-Hill Higher Education. All rights reserved. Chapter 2 Genetics: You and Your Family Health History