Your Family Health History 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

Sample Family Health Tree

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 © BannanaStock/PictureQuest

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

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) © Alamy Images

Chromosomes, Genes, and DNA

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

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 © Getty Images

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

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 © Ned Frisk Photography/Brand X Pictures/Jupiterimages

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

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

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

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

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 © Blend Images

Management and Treatment of Genetic Conditions Treatments may include: Dietary Modification Medication Environmental Adaptation Gene Therapy

Implications of Genetic Research Controversial issues in genetic screening and testing Issues of privacy and discrimination Workplace discrimination Health insurance discrimination Eugenics (selective breeding)