Human Genetics 9102020 1 1 Human Genetics 2

Human Genetics 9/10/2020 1 1

Human Genetics 2

History of Blood Typing Karl Landsteiner • Experiments with blood transfusions had been carried out for hundreds of years. • Mixing blood from two individuals can lead to severe blood clotting (agglutination). • In 1901, Karl Landsteiner discovered that blood clumping occurred because of a difference in the blood antigens and antibodies for each blood type. • His work made it possible to determine blood types and thus paved the way for safe blood transfusions.

Dr. Charles Drew • Today's American Red Cross blood program is the result of the efforts of Dr. Charles R. Drew, a blood specialist, surgeon, educator and scientist. • His pioneering work in blood collection, plasma processing and transfusion laid the foundation for modern blood banking.

Did you Know? • That Drew attended Amherst College in Massachusetts, then medical school at Montreal's Mc. Gill University in Canada. • At Amherst College, Drew received an athletic scholarship and was made captain of the school’s track team and winner of the football team's most valuable player award. • That he made many of his discoveries on blood while doing graduate research at Columbia University in New York City. • That Drew became the first African American to receive a Doctor of Medical Science degree from Columbia University. • That he returned to his hometown of Washington, D. C. , from the Red Cross blood project in New York and continued to teach the next generation of African American doctors as a professor of surgery at Howard University.

Dr. Charles Drew 6

Multiple Alleles Traits that are controlled by more than two alleles. Blood type in humans is controlled by three alleles: A, B, and O Phenotype Genotype A AA or AO B BB or BO AB AB only O OO only • The Universal Recipient can receive blood from any blood type. The • The Universal Donor can donate blood to a person any blood type. The • Which blood type is the Universal Donor? O Which blood type is the Universal Donor? 9/10/2020 • Which blood type is the Universal Recipient? AB Which blood type is the Universal Recipient? + 7

Phenotype/ Blood Type Genotype Meaning ii Neither A nor B antigens are present A IAi or IA IA Only the A antigen is present B IBi or IB IB Only the B antigen is present AB IAIB O 9/10/2020 A & B antigens are present 8

ABO Blood Types 9

Multiple Alleles – Blood Types Examples of Blood type crosses 9/10/2020 10 10

Multiple Alleles – Blood Types 11

What happens when different blood types are mixed? • Not all blood groups are compatible with each other. • Mixing incompatible blood groups leads to blood clumping or agglutination, which is dangerous for individuals. • This occurs because the antibodies of the recipients’ blood attach to the antigens of the donor blood. • The red blood cells are linked together, like bunches of grapes, by the antibodies.

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Polygenic • Definition: Disease or trait that is under the influence of two or more genes. • Remember that most of the genetics problems that we did only considered one gene for each trait.

Some common polygenic traits • Hair color • Eye color • Tendency to have certain diseases (family history)

Polygenic Traits 18

Family history’s role in polygenic diseases • You don’t inherit things like cancer or heart disease from your parents. • However, your combination of genes may make you more susceptible to certain diseases. • This is due to a combination of factors (inherited genes) instead of one particular gene.

Polygenic Diseases • These diseases are thought to be largely contributed to polygenic inheritance. – – – Cancer Heart disease Diabetes Obesity Autoimmune diseases Hip dysplasia in some dog species is a polygenic trait

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Human Heredity • Human Chromosomes – each person has 46 chromosomes. • There are two types of human chromosomes: known as sex chromosomes. • Sex Chromosomes determine an individual’s sex. (X-Female) & (Y-Male) 22

Human Heredity • Females have 2 X-chromosomes • Males have 1: X-chromosome 1: Y-chromosome • The remaining 44 chromosomes are called autosomes. • Autosomes: are chromosomes that are not sex chromosomes. 9/10/2020 23

Human Hereditary • In females the egg cells carries a single X chromosome (23 X) • In males: half of the sperm cells carry and X chromosome (23 X) and half carry the Y chromosome (23 Y). • Females Males XX, 46 XY, 46 9/10/2020 24

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Human Chromosomes • Karyotype – is a set of photographic pictures of chromosomes arranged or grouped in ordered pairs. 26

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Karyotyping • Karyotype is a picture of a person’s chromosomes, grouped in pairs. • Spectral karyotype has dye added that causes similar chromosomes to be stained the same color.

Normal Female 46, XX

Normal Male, 46 XY

Amniocentesis • a needle is used to extract sloughed off cells from amniotic fluid surrounding fetus. • Cells are then “frozen” at Metaphase so that chromosomes can be paired up

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Alpha Fetal Protein Test • In cases where there is not a large risk of genetic disorders, a safer alternative is used. • AFP detects proteins in the mother’s blood that is shared with baby. • Proteins can tell tendency for baby to have certain diseases/disorders. • Not as accurate as amniocentesis, but safer

Ultrasound technology • 2 dimensional picture • Bounces sound waves off of the fetus, and projects an image on a screen • New “ 4 D” ultrasounds can show movement and clear pictures of baby’s face.

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Chromosomal Disorders • Down’s Syndrome (trisomy 21) • Trisomy = extra chromosome • Results in mental retardation, as well as several physical disabilities.

AUTOSOMAL TRISOMIES The only Autosomal Trisomy that is compatible with life is Down Syndrome. 37

Down’s Syndrome • Trisomy 21 • Mental retardation, speech trouble, heart conditions • No Tx

Down’s Syndrome – Trisomy 21 9/10/2020 39 39

Down’s Syndrome – Trisomy 21 40

Down’s Syndrome Trisomy 21

Chromosomal Abnormalities 42

Edward’s Syndrome • Trisomy 18 • Severe mental retardation • Other physical abnormalities

Patau Syndrome • Trisomy 13 • Leads to severe cerebral development problems • Almost always leads to death during infancy • Heart defects

Turner Syndrome • Happens when an X carrying sperm fertilizes an egg with no X. • Girls appear normal until puberty • At maturity, no secondary sex characteristics develop, and woman does not produce an egg.

Kleinfelter’s Syndrome 46, XXY

Klinefelter Syndrome • XXY – extra female sex chromosome • Tall stature, small testicles, and sterile • Most of these men appear normal otherwise

Klinefelter’s Syndrome • XXY • Trisomy of sex chromosomes

Jacobsen’s Syndrome • XYY • More aggressive male • Weak correlation between XYY and prisoners

PKU (phenylketonuria) • Autosomal recessive • Brain degeneration • Tx = avoid phenylalanine

Hemophilia • Sex linked (x linked recessive) • Free bleeding • Tx= transfusion

Hemophilia 52

Human Genetics 3 major Autosomal Disorders 1. Sickle Cell Anemia 2. Cystic Fibrosis 3. Huntington’s Disease 53

Sickle Cell Anemia • Sickle cell anemia is an inherited disease. People who have the disease inherit two copies of the sickle cell gene—one from each parent. • In sickle cell anemia, the red blood cells become to stiff and are shaped like a sickle, or “C. ” The sickled red blood cells tend to stick together and get caught in the blood vessels. 54

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Sickle Cell Anemia 57

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Cystic Fibrosis • Cystic fibrosis causes mucus to become thick and sticky, which can block the normal function of the organs. Most often, the lungs and pancreas are affected. 60

Cystic fibrosis • Cystic fibrosis (also known as CF, is a hereditary disease affecting the exocrine (mucus) glands of the lungs, liver, pancreas, and intestines, causing progressive disability due to multisystem failure. • Thick mucus production results in frequent lung infections. 61

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Huntington’s Disease • Huntington's disease, also called Huntington's chorea, chorea major, or HD, is characterized after onset by uncoordinated, jerky body movements and a decline in some mental abilities. The disorder itself isn't fatal, but as symptoms progress, complications reducing life expectancy increase. 65

Huntington’s Disease 66

Colorblindness • Sex linked (x linked recessive) • Difficulty distinguishing between red and green • No Tx

Pedigree • A pedigree chart is a chart which tells someone all of the known phenotypes for an organism and its ancestors, most commonly humans, show dogs, and race horses. 68

Pedigrees • "family tree" which is a form of pedigree chart, which shows the descendants of a particular individual, and thereby highlights sibling and cousin. 69

PEDIGREE CHARTS • A pedigree chart shows a record of the family of an individual. • It can be used to study the transmission of a hereditary condition. It is particularly useful when there are large families and a good family record over several generations. 9/10/2020 70

Pedigree • A series of symbols are used to represent different aspects of a pedigree. Below are the principal symbols used when drawing a pedigree. 9/10/2020 71

Pedigree Symbols 9/10/2020 72

Dominant Gene Pedigree • The following is the action • unaffected parents can have affected offspring • affected progeny are both male and female 9/10/2020 73

Recessive Gene Pedigree 9/10/2020 74