© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Chapter 22 Genetics and Genetically Linked Diseases

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Genetics Study of how genes are transmitted from parents to offspring Mutations Human genome

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Gene Mutations Occur occasionally at random in all cells Somatic cell mutation Chromosomal mutation

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Lethal Genes (1 of 2) Inherited mutations generally have negative consequences for individuals An inherited gene that results in death is a lethal gene The time at which lethal genes exert their deadly influence varies

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Lethal Genes (2 of 2) Each person may carry 2–3 different recessive lethal genes Two similar recessive genes must be present in an individual for the gene to be expressed People with common ancestry are more likely to share many genes

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Human Genetic Disorders (1 of 3) Difference between genetic disorders and congenital disorders Phenylketonuria Sickle cell anemia Tay-Sachs disease

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Human Genetic Disorders (2 of 3) Duchenne’s muscular dystrophy Huntington’s disease Cystic fibrosis Thalassemia

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Human Genetic Disorders (3 of 3) Hemophilia Chromosomal aberrations Mutagenic agents

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Genetic Counseling Talking with parents or prospective parents about the possibility of genetic disorders Individuals who may benefit from counseling After careful analysis a genotype is determined Diagnostic tests

© 2017 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Advances in Genetics Genetic engineering –Manipulation of genes Gene therapy –Correcting defective genes