Genetic Mutations

Mutations … are changes in the genetic material can be good or bad can be on a single gene or the whole chromosome

What is a karyotype? Picture of your chromosomes Arranged from largest to smallest quickly identify chromosomal changes

4 Types of Genetic Disorders Single gene Change in the DNA sequence More than 6000 known disorders Autosomal or sex linked 1 in 200 births cystic fibrosis, sickle cell anemia, Marfan syndrome, Huntington’s disease

Types of Genetic Disorders Multifactoral combination of environmental factors and mutations in multiple genes more complicated heart disease, high blood pressure, Alzheimer’s disease, arthritis, diabetes, cancer, and obesity

Types of Genetic Disorders Chromosomal abnormalities in chromosome structure as missing or extra copies or gross breaks and rejoining Down Syndrome

Types of Genetic Disorders Mitochondrial rare type of genetic disorder caused by mutations in the non-chromosomal DNA of mitochondria

Dominant genetic disorders On our chromosomes are a total of about 100,000 genes. Among these 100,000 genes, each person has on average 5-8 bad genes. However, these seldom have any effect at all. But sometimes there are serious errors in our genetic code and these can give us the blueprint for genetic disorder. When we have a serious genetic error, there are three primary ways that the error can be inherited (passed from generation to generation). These three patterns of inheritance are: Dominant genetic disorders Recessive genetic disorders Sex-linked genetic disorders Genetic Disorders On our chromosomes are a total of about 100,000 genes. Among these 100,000 genes, each person has on average 5-8 bad genes. However, these seldom have any effect at all. But sometimes there are serious errors in our genetic code and these can give us the blueprint for genetic disorder. When we have a serious genetic error, there are three primary ways that the error can be inherited (passed from generation to generation). These three patterns of inheritance are: Dominant genetic disorders Recessive genetic disorders Sex-linked genetic disorders

Dominant Genetic Disorders: In the dominant genetic disorder pattern of inheritance, one bad gene from either parent will cause the genetic disorder. Since only one bad gene causes the disorder, if either parent has the disorder the chance of the child inheriting the bad gene and developing the disorder is 50% with each conception.

Recessive Genetic Disorders: To develop a recessive genetic disorder both parents must contribute the same defective gene. The parents usually don't have the disorder, but are carriers for the disorder. They carry one defective gene, which is recessive, and one normal dominant gene.

Sex-linked Genetic Disorders: These disorders occur due to errors in the 23rd pair of chromosomes (the chromosomes responsible for gender). These genetic disorders occur only in males. Since males have an XY sex chromosome combination, they are vulnerable to defects on their X chromosome that lacks a partner gene on the Y. These disorders do not appear in females (which are XX) because if one of the X chromosomes has an affected gene, the partner X chromosome carries a normal gene. In females, the other X will compensate any defect on one X. Since males get a Y, there is no compensation. Although the female can carry a defective gene, females do not develop the disorder – they are carriers for the disorder.

copyright cmassengale Mendelian Genetics 4/15/2017 Sex-linked Traits Traits (genes) located on the sex chromosomes Sex chromosomes are X and Y XX genotype for females XY genotype for males Many sex-linked traits carried on X chromosome copyright cmassengale

copyright cmassengale Mendelian Genetics 4/15/2017 Sex-linked Traits Example: Eye color in fruit flies Sex Chromosomes XX chromosome - female Xy chromosome - male fruit fly eye color copyright cmassengale

Sex-linked Trait Problem Mendelian Genetics Sex-linked Trait Problem 4/15/2017 Example: Eye color in fruit flies (red-eyed male) x (white-eyed female) XRY x XrXr Remember: the Y chromosome in males does not carry traits. RR = red eyed Rr = red eyed rr = white eyed XY = male XX = female XR Xr Y copyright cmassengale

Sex-linked Trait Solution: Mendelian Genetics 4/15/2017 Sex-linked Trait Solution: XR Xr Y 50% red eyed female 50% white eyed male XR Xr Xr Y copyright cmassengale

Other Genetic Disorders: Other genetic disorders do not fall neatly into one of these three patterns. These involve having too many or too few chromosomes.

Turners Syndrome 1 in 5,000 births 45 chromosomes X only #23 Monosomy Nondisjunction

Turners Syndrome 96-98% do not survive to birth No menstruation No breast development No hips Broad shoulders and neck

Cri-Du-Chat Syndrome 1 in 216,000 births 46 chromosomes XY or XX #5 Deletion of lower arm

Cri-Du-Chat Syndrome Moon-shaped face Heart disease Mentally retarded Malformed larynx Normal lifespan

Aniridia-Wilms Tumor Syndrome 1 in 50,000,000 births 46 chromosomes XY or XX #11 Deletion of upper arm

Aniridia-Wilms Tumor Syndrome Mentally retarded Growth retarded Blindness Tumors on kidneys Short lifespan

Thirteen Q Deletion Syndrome 1 in 500,000 births 46 chromosomes XY or XX #13 Deletion of lower arm

Thirteen Q Deletion Syndrome Mentally retarded Deformed face No thumbs Heart disease Short lifespan

Prader-Willi Syndrome 1 in 5,000,000 births 46 chromosomes XY=97% XX=3% #15 Deletion of lower arm

Prader-Willi Syndrome Small bird-like head Mentally retarded Respiratory problems Obesity Short lifespan

Eighteen Q Deletion Syndrome 1 in 10,000,000 births 46 chromosomes XY or XX #18 Deletion of lower arm

Eighteen Q Deletion Syndrome Mentally retarded Heart disease Abnormal hands and feet Large eyes Large ears Normal lifespan

Cat-Eye Syndrome 1 in 1,000,000 births 46 chromosomes XY or XX #22 Deletion of bottom arm

Cat-Eye Syndrome Fused fingers and toes Mentally retarded Small jaw Heart problems Normal lifespan

Four-Ring Syndrome 1 in 10,000,000 births 46 chromosomes XY or XX #4 Inversion

Four-Ring Syndrome Cleft palate Club feet Testes don’t descend Short lifespan

Down Syndrome Trisomy Down Syndrome 1 in 31,000 births 46 chromosomes XY=97% XX=3% #14/21 Translocation 1 in 1,250 births 47 chromosomes XY or XX #21 Trisomy Nondisjunction

Down Syndrome Short, broad hands Stubby fingers Rough skin Impotency in males Mentally retarded Small round face Protruding tongue Short lifespan

Patau’s Trisomy Syndrome 1 in 14,000 births 47 chromosomes XY or XX #13 Trisomy Nondisjunction

Patau’s Trisomy Syndrome Small head Small or missing eyes Heart defects Extra fingers Abnormal genitalia Mentally retarded Cleft palate Most die a few weeks after birth

Edward’s Trisomy Syndrome 1 in 4,400 births 47 chromosomes XX=80% XY=20% #18 Trisomy Nondisjunction

Edward’s Trisomy Syndrome Small head Mentally retarded Internal organ abnormalities 90% die before 5 months of age

Jacob’s Syndrome 1 in 1,800 births 47 chromosomes XYY only #23 Trisomy Nondisjunction

? Jacob’s Syndrome Normal physically Normal mentally Increase in testosterone More aggressive Normal lifespan

Klinefelter Syndrome 1 in 1,100 births 47 chromosomes XXY only #23 Trisomy Nondisjunction

Klinefelter Syndrome Scarce beard Longer fingers and arms Sterile Delicate skin Low mental ability Normal lifespan

Triple X Syndrome 1 in 2,500 births 47 chromosomes XXX only #23 Trisomy Nondisjunction

Triple X Syndrome Normally physically Normal mentally Learning disabilities Taller than average Behavior Problems

Huntington’s Chromosome 4 mutation. involuntary twitching or movement Huntington’s Chromosome 4 mutation *involuntary twitching or movement *onset 40 yrs. *deterioration of the CNS that affects muscle control

Sickle-cell Anemia Moon shaped RBC that has low hemoglobin Shows up more often in African Americans; or whose ancestors once inhabited parts where malaria is a high risk. Sickle-shaped cells clog capillaries so that cells cannot get oxygen and nutrition Blood transfusions, pain killers, and drugs Pain, strokes, jaundice.

Cystic Fibrosis Chromosome 7 mutation Affects mucus, salivary and sweat glands. Many respiratory problems Thick, sticky mucus in lungs and digestive tracts.

Tay-Sachs No Hex A enzyme Recessive genetic disorder most often found in Jewish or eastern Europe origin. Appears in children starting at 6 mo. Child cannot metabolize a certain lipid which incases the CNS and prevents the brain from expanding. Fat builds up in the brain causing blindness & paralysis Death occurs in early childhood

Hemophilia Blood has less than 1% of the normal clotting factor Bleeds longer because blood won’t clot.

Color-blindness Cones in the eye do not perceive certain colors Most common form is reds/greens but some are brown/blue Seen as gray