Fundamentals of Fundamentals of GeneticsGenetics

Gregor MendelGregor Mendel

The father of modern The father of modern genetics – genetics – the study of hereditythe study of heredity

Experimented with garden peas Experimented with garden peas in the 1800sin the 1800s

He produced a He produced a hybridhybrid pea plant pea plant – – an organism that receives an organism that receives different genetic information different genetic information from each parentfrom each parent - in his - in his experimentsexperiments

He looked at only a few different He looked at only a few different traits, they were – seed shape, traits, they were – seed shape, color, pod shape, pod color, color, pod shape, pod color, flower position and height.flower position and height.

Gregor MendelGregor Mendel He took 2 pure bred plants – He took 2 pure bred plants – the parent contains only one gene for each the parent contains only one gene for each

genetic traitgenetic trait – and crossed them. – and crossed them. After performing his experiment he found After performing his experiment he found

Dominant trait - the trait that is expressedDominant trait - the trait that is expressed – was always expressed. – was always expressed. Usually shown as a capital letter.Usually shown as a capital letter.

Recessive traitRecessive trait – – the trait that is only when there is two of them-the trait that is only when there is two of them- usually usually shown as a lower case letter.shown as a lower case letter.

Vocabulary WordsVocabulary Words Before beginning, a vocabulary word. Before beginning, a vocabulary word.

Alleles - different versions for Alleles - different versions for the same trait.the same trait. Example: T (tall) and t (short) are alleles for the Example: T (tall) and t (short) are alleles for the gene that controls height of the pea plant.gene that controls height of the pea plant.

Homozygous – having two (2) of the same Homozygous – having two (2) of the same alleles for the same trait.alleles for the same trait.Example – TT – homozygous dominantExample – TT – homozygous dominant – – tt – homozygous recessivett – homozygous recessive

Heterozygous – having two (2) different Heterozygous – having two (2) different alleles for the same trait.alleles for the same trait.Example – TtExample – Tt

More Vocabulary WordsMore Vocabulary Words

Genotype – the genes that an organism Genotype – the genes that an organism possessespossesses

Phenotype – the way the genes are Phenotype – the way the genes are expressed (how the organism looks)expressed (how the organism looks)

Can you answer this question?Can you answer this question? How does your genotype control your How does your genotype control your

phenotype. phenotype.

Mendel’s LawsMendel’s Laws 1. Law of Segregation - 1. Law of Segregation -

each pair of alleles each pair of alleles segregates, or separates segregates, or separates during meiosis.during meiosis.

2. Law of Dominance – An 2. Law of Dominance – An allele that always controls allele that always controls a trait is called the a trait is called the dominant allele. An allele dominant allele. An allele that is hidden when paired that is hidden when paired with a dominant allele is with a dominant allele is called a recessive genecalled a recessive gene

Mendel’s LawsMendel’s Laws

3. Law of 3. Law of Independent Independent Assortment – the Assortment – the association of traits association of traits in a parent does not in a parent does not seem to matter. seem to matter. Mendel concluded Mendel concluded that traits, or factors, that traits, or factors, are inherited are inherited independently.independently.

More with the More with the Fundamentals of Fundamentals of

GeneticsGenetics

Since Mendels’ time, Biologists have discovered other more complex patterns of inheritance and expressions. Because of these new discoveries the scientific community has extended his laws.

Incomplete dominanceIncomplete dominance Incomplete dominance ocures when a Incomplete dominance ocures when a

heterozygote shows the phenotype that is heterozygote shows the phenotype that is intermediate between the two homozygous intermediate between the two homozygous phenotypes. ( Neither homozygous dominant phenotypes. ( Neither homozygous dominant nor homozygous recessive is fully expressed)nor homozygous recessive is fully expressed)

CodominanceCodominance

• Another form of intermediate inheritance is codominance.

• Codominance is when both alleles in the heterozygote express themselves fully.

Polygenic TraitsPolygenic Traits

When a trait is When a trait is controlled by two or controlled by two or more gene pairs it is more gene pairs it is called polygenetic called polygenetic traits. traits.

Human eye color and Human eye color and hair color are hair color are examples of examples of polygenic traitspolygenic traits

Multiple AllelesMultiple Alleles

When there are When there are three or more three or more alleles for a trait alleles for a trait in the population.in the population.

Human blood Human blood

type genes exist type genes exist as multiple as multiple alleles.alleles.

Pedigree ChartsPedigree Charts

The family tree of geneticsThe family tree of genetics

What is a Pedigree?What is a Pedigree?

A pedigree is a chart of the genetic history A pedigree is a chart of the genetic history of family over several generations.of family over several generations.

Scientists or a genetic counselor would find Scientists or a genetic counselor would find out about your family history and make this out about your family history and make this chart to analyze.chart to analyze.

Constructing a PedigreeConstructing a Pedigree

MaleMale

FemaleFemale

Connecting Pedigree Connecting Pedigree SymbolsSymbols

Fraternal twinsFraternal twins

Identical twinsIdentical twins

Examples of connected symbols:Examples of connected symbols:

Connecting Pedigree Connecting Pedigree SymbolsSymbols

Married CoupleMarried Couple

SiblingsSiblings

Examples of connected symbols:Examples of connected symbols:

ExampleExample

What does a pedigree chart look like?What does a pedigree chart look like?

SummarySummary

Pedigrees are family trees that explain Pedigrees are family trees that explain your genetic history.your genetic history.

Pedigrees are used to find out the Pedigrees are used to find out the probability of a child having a disorder in a probability of a child having a disorder in a particular family.particular family.

To begin to interpret a pedigree, determine To begin to interpret a pedigree, determine if the disease or condition is autosomal or if the disease or condition is autosomal or X-linked and dominant or recessive.X-linked and dominant or recessive.

Human Genetic DisordersHuman Genetic Disorders

Sickle Cell AnemiaSickle Cell Anemia

Sickle Cell anemia is an inherited red blood cell Sickle Cell anemia is an inherited red blood cell disorder. Normal red blood cells are round like disorder. Normal red blood cells are round like doughnuts, and they move through small blood tubes doughnuts, and they move through small blood tubes in the body to deliver oxygen. in the body to deliver oxygen.

Sickle red blood cells become hard, sticky and shaped Sickle red blood cells become hard, sticky and shaped like sickles used to cut wheat. When these hard and like sickles used to cut wheat. When these hard and pointed red cells go through the small blood tube, they pointed red cells go through the small blood tube, they clog the flow and break apart. This can cause pain, clog the flow and break apart. This can cause pain, damage and a low blood count, or anemia.damage and a low blood count, or anemia.

HemophiliaHemophilia

• Hemophilia is a hereditary Hemophilia is a hereditary (X-linked, recessive) blood (X-linked, recessive) blood disorder that affects the disorder that affects the proper clotting of blood. proper clotting of blood.

• It is a disease that affects It is a disease that affects males much more males much more frequently (1 in 10,000) frequently (1 in 10,000) than females (1 in than females (1 in 100,000,000). 100,000,000).

• This occurs because a This occurs because a critical blood-clotting gene critical blood-clotting gene is carried on the X is carried on the X chromosome. chromosome.

AlbinismAlbinism

• a disorder that occurs a disorder that occurs when a person inherits when a person inherits various genesvarious genes that are that are defective in their ability to defective in their ability to make the pigment melaninmake the pigment melanin

• Melanin is the main Melanin is the main substance that determines substance that determines a person's skin, hair, and a person's skin, hair, and eye color. eye color.

• In the United States, In the United States, albinism affects albinism affects approximately 1 in 17,000 approximately 1 in 17,000 people.people. http://www.humanillnesses.com/original/A-

As/Albinism.html

Cystic FibrosisCystic Fibrosis

Tay Sachs DiseaseTay Sachs Disease

• caused by a missing caused by a missing enzyme that results in enzyme that results in the accumulation of a the accumulation of a fatty substance in the fatty substance in the nervous system nervous system

• causes disability and causes disability and deathdeath

• common among common among Jewish people of Jewish people of Eastern European and Eastern European and Russian (Ashkenazi) Russian (Ashkenazi) originorigin

Section of brain tissue from patient with Tay-Sachs disease. (© 1992 IMS Creative. Custom Medical Stock Photo, Inc.)

ColorblindnessColorblindness

non-fatal health condition which is non-fatal health condition which is characterized by difficulty in characterized by difficulty in identifying and recognizing identifying and recognizing different colors and shadesdifferent colors and shades

may either be caused due to may either be caused due to genetic reasons or may be genetic reasons or may be acquired during the later stages of acquired during the later stages of life due to diseases effecting the life due to diseases effecting the optic nerve or retina. optic nerve or retina.

Inherited color vision problem is Inherited color vision problem is usually linked to the X-usually linked to the X-chromosome and is passed from a chromosome and is passed from a mother to her son.mother to her son.

affects more males (8 percent) affects more males (8 percent) than females (0.4 percent) than females (0.4 percent)

http://www.scumdoctor.com/disease-prevention/eye-diseases/Symtoms-Of-Color-Blindness.html

Adrenoleukodystrophy Adrenoleukodystrophy (Lorenzo’s Oil)(Lorenzo’s Oil)

• The condition results in the The condition results in the buildup of very-long-chain fatty buildup of very-long-chain fatty acids in the nervous system, acids in the nervous system, adrenal gland, and testes, which adrenal gland, and testes, which disrupts normal activitydisrupts normal activity

• There are three major categories There are three major categories of disease:of disease:– Childhood cerebral form -- appears Childhood cerebral form -- appears

in mid-childhood (at ages 4 - 8) in mid-childhood (at ages 4 - 8) – Adrenomyelopathy --occurs in men Adrenomyelopathy --occurs in men

in their 20s or later in life in their 20s or later in life – Impaired adrenal gland function Impaired adrenal gland function

(called Addison disease or (called Addison disease or Addison-like phenotype) -- adrenal Addison-like phenotype) -- adrenal gland does not produce enough gland does not produce enough steroid hormonessteroid hormones

Hereditary DeafnessHereditary Deafness

hearing loss that is hearing loss that is inherited or passed down inherited or passed down from parents to their from parents to their childrenchildren

may be inherited from may be inherited from one or both parents who one or both parents who may or may not have a may or may not have a loss of hearing loss of hearing themselvesthemselves

http://www.medhelp.org/http://www.medhelp.org/lib/heredeaf.htmlib/heredeaf.htm

http://www.boystownhospital.org/Images/Hearing/info/xlinkrec.gif

Coffin-Lowry SyndromeCoffin-Lowry Syndrome

a condition that affects a condition that affects many parts of the bodymany parts of the body

Males typically have Males typically have severe to profound severe to profound intellectual disability and intellectual disability and delayed developmentdelayed development

women may be women may be cognitively normal, or cognitively normal, or they may have intellectual they may have intellectual disability ranging from disability ranging from mild to profoundmild to profound

http://jmg.bmj.com/content/vol39/issue10/images/large/mg02984.f3.jpeg

http://ghr.nlm.nih.gov/condition=coffinlowrysyndrome

Achondroplasia Achondroplasia (dwarfism)(dwarfism)

characterized by characterized by abnormal bone growth abnormal bone growth that results in short that results in short stature with stature with disproportionately short disproportionately short arms and legs, a large arms and legs, a large head, and characteristic head, and characteristic facial features with facial features with frontal bossing and mid-frontal bossing and mid-face hypoplasiaface hypoplasia http://www.mun.ca/biology/scarr/Achondroplasia_in_humans.htm

http://www.geneclinics.org/profiles/achondroplasia/details.html

Fragile X SyndromeFragile X Syndrome

Fragile X syndrome is Fragile X syndrome is the most common the most common inherited cause of inherited cause of mental impairment. mental impairment.

The syndrome occurs The syndrome occurs in approximately 1 in in approximately 1 in 3600 males and 1 in 3600 males and 1 in 4000 to 6000 females.4000 to 6000 females.

Leading causes of Leading causes of autismautism

http://www.fragilex.org/html/summary.htmhttp://geneticsmodules.duhs.duke.edu/Design/images/fragileX.jpg

Huntington’s DiseaseHuntington’s Disease

results from genetically results from genetically programmed degeneration of programmed degeneration of brain cells, called neurons, in brain cells, called neurons, in certain areas of the braincertain areas of the brain

This degeneration causes This degeneration causes uncontrolled movements, loss uncontrolled movements, loss of intellectual faculties, and of intellectual faculties, and emotional disturbance.emotional disturbance.

HD is a familial disease, HD is a familial disease, passed from parent to child passed from parent to child through a mutation in the through a mutation in the normal genenormal gene

http://pet.radiology.uiowa.edu/webpage/Research/CaseStudies/BrainHuntingtonsDisease.html

Marfan Syndrome (Alton Marfan Syndrome (Alton Giant)Giant)

disorder of connective tissue which disorder of connective tissue which causes skeletal defects typically causes skeletal defects typically recognized in a tall, lanky personrecognized in a tall, lanky person

may exhibit long limbs and spider-may exhibit long limbs and spider-like fingers, chest abnormalities, like fingers, chest abnormalities, curvature of the spine and a curvature of the spine and a particular set of facial features particular set of facial features including a highly arched palate, including a highly arched palate, and crowded teethand crowded teeth

the most significant of the defects the most significant of the defects in the syndrome are cardiovascular in the syndrome are cardiovascular abnormalities, which may include abnormalities, which may include enlargement (dilatation) of the base enlargement (dilatation) of the base of the aorta. of the aorta. http://www.nytimes.com/imagepages/2007/08/01/health/adam/9611Marfansyndrome.html

Trisomy 13 (Edward’s Trisomy 13 (Edward’s Syndrome)Syndrome)

chromosomal condition associated with chromosomal condition associated with severe intellectual disability and severe intellectual disability and physical abnormalities in many parts of physical abnormalities in many parts of the bodythe body

Individuals with trisomy 13 often have Individuals with trisomy 13 often have heart defects, brain or spinal cord heart defects, brain or spinal cord abnormalities, very small or poorly abnormalities, very small or poorly developed eyes, extra fingers and/or developed eyes, extra fingers and/or toes, an opening in the lip (a cleft lip) toes, an opening in the lip (a cleft lip) with or without an opening in the roof of with or without an opening in the roof of the mouth (a cleft palate), and weak the mouth (a cleft palate), and weak muscle tonemuscle tone

many infants with trisomy 13 die within many infants with trisomy 13 die within their first days or weeks of life.their first days or weeks of life.

Only five percent to 10 percent of Only five percent to 10 percent of children with this condition live past children with this condition live past their first year.their first year.

http://www.livingwithtrisomy13.org/Trisomy-13_KailaRecent.jpg

http://ghr.nlm.nih.gov/condition=trisomy13

Phenylketonuria (PKU)Phenylketonuria (PKU)

inherited disorder that increases inherited disorder that increases the levels of a substance called the levels of a substance called phenylalanine in the bloodphenylalanine in the blood

a building block of proteins (an a building block of proteins (an amino acid) that is obtained amino acid) that is obtained through the dietthrough the diet

found in all proteins and in found in all proteins and in some artificial sweetenerssome artificial sweeteners

If PKU is not treated, If PKU is not treated, phenylalanine can build up to phenylalanine can build up to harmful levels in the body, harmful levels in the body, causing intellectual disability causing intellectual disability and other serious health and other serious health problemsproblems

http://www.dshs.state.tx.us/newborn/images/PKU_untreated.jpg

http://ghr.nlm.nih.gov/condition=phenylketonuria

Rett SyndromeRett Syndrome

childhood childhood neurodevelopmental neurodevelopmental disorder that affects disorder that affects females almost females almost exclusivelyexclusively

Loss of muscle tone is Loss of muscle tone is usually the first symptomusually the first symptom

Other early symptoms Other early symptoms may include problems may include problems crawling or walking and crawling or walking and diminished eye contact. diminished eye contact.

http://www.scoliosisjournal.com/content/figures/1748-7161-2-15-1-l.jpg

http://www.ninds.nih.gov/disorders/rett/rett.htm

Klinefelter Syndrome Klinefelter Syndrome (XXY Male)(XXY Male)

condition that occurs in men who have condition that occurs in men who have an extra X chromosome in most of their an extra X chromosome in most of their cells. cells.

The syndrome can affect different stages The syndrome can affect different stages of physical, language and social of physical, language and social development. development.

The most common symptom is infertility. The most common symptom is infertility. Because they often don't make as much Because they often don't make as much

of the male hormone testosterone as of the male hormone testosterone as other boys, teenagers with Klinefelter's other boys, teenagers with Klinefelter's syndrome may have less facial and body syndrome may have less facial and body hair and may be less muscular than other hair and may be less muscular than other boys. boys.

They may have trouble using language They may have trouble using language to express themselves. to express themselves.

They may be shy and have trouble fitting They may be shy and have trouble fitting in.in.

http://www.nlm.nih.gov/medlineplus/klinefelterssyndrome.html

http://www.healthofchildren.com/images/gech_0001_0002_0_img0156.jpg

Turner SyndromeTurner Syndrome

disorder caused by the loss of disorder caused by the loss of genetic material from one of the genetic material from one of the sex chromosomes. sex chromosomes.

affects approximately 1 out of affects approximately 1 out of every 2,500 female live births every 2,500 female live births worldwide. worldwide.

broad spectrum of features, from broad spectrum of features, from major heart defects to minor major heart defects to minor cosmetic issues. cosmetic issues.

Almost all people with Turner Almost all people with Turner syndrome have short stature and syndrome have short stature and loss of ovarian function, but the loss of ovarian function, but the severity of these problems varies severity of these problems varies considerably amongst individuals. considerably amongst individuals.

http://turners.nichd.nih.gov/

Progeria (premature Progeria (premature aging)aging)

rare condition that is remarkable rare condition that is remarkable because its symptoms strongly because its symptoms strongly resemble normal human aging, resemble normal human aging, but occur in young children.but occur in young children.

Ninety percent of children with Ninety percent of children with progeria have a mutation on the progeria have a mutation on the gene that encodes the protein gene that encodes the protein lamin A. lamin A.

Progeria usually occurs without Progeria usually occurs without cause. cause.

It is not seen in siblings of affected It is not seen in siblings of affected children, although -- in very rare children, although -- in very rare circumstances -- more than one circumstances -- more than one child in a family can have the child in a family can have the condition.condition.

http://www.nlm.nih.gov/medlineplus/ency/article/001657.htm

http://images.google.com/images?gbv=2&hl=en&sa=3&q=progeria

Xeroderma PigmentosumXeroderma Pigmentosum

an autosomal recessive an autosomal recessive genetic disorder.genetic disorder.

characterized by abnormal characterized by abnormal pigmentation on the Sun pigmentation on the Sun exposed areas of the skinexposed areas of the skin

extreme sensitivity of the extreme sensitivity of the skin to Sunlight and marked skin to Sunlight and marked predisposition to skin cancer. predisposition to skin cancer.

In some cases growth and In some cases growth and mental retardation are also mental retardation are also associated with this associated with this syndrome. syndrome.

http://phobos.ramapo.edu/~pbagga/xpcs.htm

Gaucher DiseaseGaucher Disease

inherited metabolic inherited metabolic disorder in which disorder in which harmful quantities of a harmful quantities of a fatty substance called fatty substance called glucocerebrosideglucocerebroside accumulate in the accumulate in the spleen, liver, lungs, spleen, liver, lungs, bone marrow, and bone marrow, and sometimes in the sometimes in the brain. brain.

http://www.ninds.nih.gov/disorders/gauchers/gauchers.htm

http://history.nih.gov/exhibits/genetics/images/sect3/3-sm.jpg

Prader-Willi SyndromePrader-Willi Syndrome

a problem in their a problem in their hypothalamus, a part of the hypothalamus, a part of the brain that normally controls brain that normally controls feelings of fullness or hunger.  feelings of fullness or hunger.  As a result, they never feel As a result, they never feel full and have a constant urge full and have a constant urge to eat that they cannot to eat that they cannot control. control. 

Most cases of Prader-Willi Most cases of Prader-Willi syndrome result from a syndrome result from a spontaneous genetic error in spontaneous genetic error in genes on chromosome 15 genes on chromosome 15 that occurs at conception.  In that occurs at conception.  In very rare cases, the mutation very rare cases, the mutation is inherited.is inherited.

http://www.nichd.nih.gov/health/topics/Prader_Willi_Syndrome.cfm

http://www.scotland.gov.uk/Resource/Img/54357/0009794.jpg

Duchenne Muscular Duchenne Muscular Dystrophy Dystrophy

a rapidly-worsening form of a rapidly-worsening form of muscular dystrophymuscular dystrophy

caused by a defective gene for caused by a defective gene for dystrophin (a protein in the dystrophin (a protein in the muscles)muscles)

males are more likely to develop males are more likely to develop symptoms than are women symptoms than are women

The sons of females who are The sons of females who are carriers of the disease (women carriers of the disease (women with a defective gene but no with a defective gene but no symptoms themselves) each symptoms themselves) each have a 50% chance of having the have a 50% chance of having the disease disease

The daughters each have a 50% The daughters each have a 50% chance of being carriers.chance of being carriers.

occurs in approximately 1 out of occurs in approximately 1 out of every 3,600 male infantsevery 3,600 male infants

http://www.dinf.ne.jp/doc/english/global/david/dwe002/dwe002g/dwe00212g01.gif

http://www.nlm.nih.gov/medlineplus/ency/article/000705.htm

Down SyndromeDown Syndrome

is set of mental and physical is set of mental and physical symptoms that result from symptoms that result from having an extra copy of having an extra copy of Chromosome 21.  Chromosome 21. 

Normally, a fertilized egg has Normally, a fertilized egg has 23 pairs of chromosomes.  23 pairs of chromosomes. 

In most people with Down In most people with Down syndrome, there is an extra syndrome, there is an extra copy of Chromosome 21 (also copy of Chromosome 21 (also called trisomy 21 because called trisomy 21 because there are three copies of this there are three copies of this chromosome instead of two), chromosome instead of two), which changes the body’s which changes the body’s and brain’s normal and brain’s normal development. development. 

http://www.miscarriage.com.au/images/pages/t21karyo.jpg

http://www.nichd.nih.gov/health/topics/Down_Syndrome.cfm

Unusual Inherited Disorders

Werewolf Syndrome

Manuel Aceves

Hirsute ManGerman, c. 1580It is a portrait of Petrus Gonsalvus. Born in 1556, he came as a child to the court of the French King Henry II, who had him trained and educated.

Children of Petrus Gonsalvus.

Brachydactly

Syndactyly

Polydactyly

Fugate Family with rare blood disease called (methemoglobinemia)

Kentucky Blue People

Fugate Family pedigree Kentucky Blue People