Human Diseases A Systemic Approach Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. CHAPTER Human Diseases: A Systemic Approach, Seventh Edition Mark Zelman, Elaine Tompary, Jill Raymond, Paul Holdaway, and Mary Lou Mulvihill Heredity and Disease 5Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Human Diseases: A Systemic Approach, Seventh Edition Mark Zelman, Elaine Tompary, Jill Raymond, Paul Holdaway, and Mary Lou Mulvihill Chapter 5 Objectives • Describe DNA’s composition and its role in heredity • Describe general mechanisms of transmission of hereditary diseases and give examples • Explain genetic diseases based on abnormal chromosome construction • Highlight: Down Syndrome • Discuss screening techniques and the concept of gene therapy • Distinguish between congenital and hereditary conditionsCopyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Human Diseases: A Systemic Approach, Seventh Edition Mark Zelman, Elaine Tompary, Jill Raymond, Paul Holdaway, and Mary Lou Mulvihill Heredity: The Basics • DNA = the blueprint for directing cell activities • Chromosomes = assembled strands of DNA within the nucleus • 44 autosomes (22 pairs) • 2 sex chromosomes: • Female: XX Male: XY • Karyotype = the complete chromosomal compositionCopyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Human Diseases: A Systemic Approach, Seventh Edition Mark Zelman, Elaine Tompary, Jill Raymond, Paul Holdaway, and Mary Lou Mulvihill Figure 5-3: Normal human karyotype. (©Custom Medical Stock Photo.) Chromosomes can be extracted from the nucleus & photographed under a microscope in order to detect abnormalitiesCopyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Human Diseases: A Systemic Approach, Seventh Edition Mark Zelman, Elaine Tompary, Jill Raymond, Paul Holdaway, and Mary Lou Mulvihill Genetic Inheritance • Genes for a particular trait (e.g., hair color) occupy a particular site on a chromosome • Each person has 2 copies of each gene; 1 from each parent • Alleles = alternate forms of a gene – Homozygous – the same (e.g., BB or bb) – Heterozygous – different (e.g., Bb) – Dominant – when only one allele is need to express a trait (e.g., Bb results in brown hair) – Recessive – when two are needed to express a trait (e.g., the red hair allele is recessive)Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Human Diseases: A Systemic Approach, Seventh Edition Mark Zelman, Elaine Tompary, Jill Raymond, Paul Holdaway, and Mary Lou Mulvihill Autosomal Dominant Diseases • Occur through transmission of a dominant allele • Offspring have 50% chance of being affected, if one parent has normal karyotype • Males and females have equal chance of being affectedCopyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Human Diseases: A Systemic Approach, Seventh Edition Mark Zelman, Elaine Tompary, Jill Raymond, Paul Holdaway, and Mary Lou Mulvihill Figure 5-4: Transmission of autosomal dominant disorders. (50% chance for an affected child). Doesn't mean if you have 4 kids that 2 will have the disease.Know how to do these for examCopyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Human Diseases: A Systemic Approach, Seventh Edition Mark Zelman, Elaine Tompary, Jill Raymond, Paul Holdaway, and Mary Lou Mulvihill Examples of Autosomal Dominant Diseases • Polydactyly • Achondroplasia • Abnormal cartilage formation • Marfan syndrome • The connective tissue protein “fibrillin” is missing • Familial hypercholesterolemia Results in very tall person, Lincoln Results in very short personCopyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Human Diseases: A Systemic Approach, Seventh Edition Mark Zelman, Elaine Tompary, Jill Raymond, Paul Holdaway, and Mary Lou Mulvihill Autosomal Recessive Diseases • Disease manifests when individual is homozygous for the defective allele • Heterozygous parents are carriers; they do not have the disease • Child has a 25% chance of being affected • Recessive allele appears more frequently in close intermarriagesCopyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Human Diseases: A Systemic Approach, Seventh Edition Mark Zelman, Elaine Tompary, Jill Raymond, Paul Holdaway, and Mary Lou Mulvihill Figure 5-6: Transmission of recessive disorders (25% chance for an affected child).Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Human Diseases: A Systemic Approach, Seventh Edition Mark Zelman, Elaine Tompary, Jill Raymond, Paul Holdaway, and Mary Lou Mulvihill Examples of Autosomal Recessive Diseases • Phenylketonuria (PKU) Newborns are screened immediately If trait is found, a synthetic diet is offered (e.g., Lofenalac), which greatly reduces risk Missing enzyme: Phenylalanine HydroxylaseCopyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Human Diseases: A Systemic Approach, Seventh Edition Mark Zelman, Elaine Tompary, Jill Raymond, Paul Holdaway, and Mary Lou Mulvihill • Sickle cell anemia • The black population most at risk • 1 in 12 are carriers • Hemoglobin is abnormal, results in deformed red blood cells • Deformed cells lodge and block circulation • SUPER INTERESTING FACT: (!) – Heterozygous individual does not have the disease, but will experience mild anemia, BUT… – The defective allele confers increased resistance to ___________, which kills _____ million people a year! More Examples of Autosomal Recessive Diseases http://www.youtube.com/watch?v=2CsgXHdWqVs watch!Malaria2Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Human Diseases: A Systemic Approach, Seventh Edition Mark Zelman, Elaine Tompary, Jill Raymond, Paul Holdaway, and Mary Lou Mulvihill •Galactosemia •Tay-Sachs disease •Albinism More Examples of Autosomal Recessive Diseases Research one of these for examCopyright ©2010 by Pearson Education, Inc.