genetic disorders : autosomal & sex linked traits
DESCRIPTION
Genetic Disorders : Autosomal & Sex Linked Traits. Karyotype: All of the chromosomes that an individual has in their body. Autosomes: All chromosomes except your sex chromosomes Sex Chromosomes: Determine which gender you will be. Autosomal Recessive Disorders. - PowerPoint PPT PresentationTRANSCRIPT
Genetic Disorders:Autosomal
&Sex Linked
Traits
Karyotype: All of the chromosomes that an individual has in their body
• Autosomes: All chromosomes except your sex chromosomes
• Sex Chromosomes: Determine which gender you will be
Autosomal Recessive Disorders
• Recessive genes found on an autosome that cause a particular disorder.
• DD = Normal
• Dd = Carrier
• dd = Affected by disorder
2 Examples of Autosomal Recessive
Disorders
Tay-Sachs Disease• A genetically caused disease in which the
gene to make the enzyme Hex-A (Hexosaminidase A) is not working.
• Hex-A is an enzyme that breaks down the lipid GM2 ganglioside.
• Without Hex-A this lipid accumulates on nerve cells, specifically in the brain causing severe brain damage.
• Victims of this disorder do not live past age 5
Tay-Sachs Brain
Tay-Sachs Carriers
Offspring:
25% Normal
50% Carriers
25% Tay-Sachs
Common in Eastern European Ashkenazi Jews
• This is a group of people descendent of medieval Jews from the Rhineland area. (Rhineland: near the river Rhine in Germany)
Cystic Fibrosis 7q31
• Thick mucus is produced by the body–Mucus fills lungs causing lung
infections–Mucus blocks pancreas which causes
digestive problems–Mucus can block bile ducts in liver
causing liver failure.
Cystic Fibrosis
Cystic Fibrosis
Effects
1/30 Caucasians
Carriers of Cystic Fibrosis
Offspring:25% Normal50% Carriers25% Cystic Fibrosis
Autosomal Dominant Disorders• Dominant genes found on an
autosome that cause a particular disorder.
• Affects people after their reproductive years
• DD = Affected
• Dd = Affected
• dd = Normal
1 Example
Huntington’s Disease• Genetically programmed
degeneration of brain cells. • Mood swings, loss of muscle control, loss
of memory and inability to learn, death.
• hh = Normal
• HH or Hh = will get and die of this disease
Person with Huntington’s and a person without Huntington’s
Hh x hh
Offspring:
50% Huntington’s
50% Normal
Huntington’s is most common in Venezuela
•An autosomal disorder: person has 3 homologous chromosomes instead of 2 homologous chromosomes-Often die between conception (when sperm
meets egg) and 1 year old.
Trisomy:
1 Example
Down Syndrome:
• Genotype: 3 copies of 21st chromosome
Chances of Getting Downs
• Age 25: 0.076%
• Age 35: 0.27%
• Age 45: 3.3%
Phenotype: Skin folds above the eye, some cardiac deformities, some levels of mental retardation, extra large tongue
Phenotype: Skin folds above the eye, some cardiac deformities, some levels of mental retardation, extra large tongue
Downs Karyotype
Sex Linked Traits
Sex Linked Traits
• Traits that occur on the X or Y chromosome
2) X Linked: A trait that occurs on the X chromosome.
a) More likely to affect men because men only get one X chromosome.
b) Women must get two recessive chromosomes to show the disorder
3) Colorblind
Phenotype: • The affected person does not
have color vision: usually no green or red (men: 8%, women 0.4%)
How to write a Alleles for Sex Linked Traits
• Women:–Normal: XBXB
–Carrier: XBXb
–Colorblind: XbXb • Men:
–Normal: XBY–Colorblind: XbY
Colorblind Test!
• You will be given a colorblind test.
• You will see circles with many colors of dots
• The dot pattern makes up a number
• What number do you see?
With Color Vision:
Color Blind Test
What number do you see?
Color Blind Test
What number do you see?
This what you would see if you were color blind
What number do you see?
Color Blind Test
What number do you see?
Color Blind Test
What number do you see?
Color Blind Test
What number do you see?
Color Blind Test
What number do you see?
With color vision you see this:
But if you were red-green colorblind….
You would see the #:
5
What do the colorblind see?
NORMALPROTAN:
Red BlindDEUTERAN:Green Blind
TRITAN:Blue Blind
RED
YELLOW
GREEN
CYAN
BLUE
MAGENTA
Types of Colorblindness
http://www.visitliverpool.jp/nature/images/knowsley-wildflower.jpg
Types of Colorblindness –
Normal No color vision
Protanopia: no red Deuteranopia: no green Tritanopia: no blue
Hemophilia • A genetic sex linked gene that affects the
way your blood clots. (affects clotting factor VIII and IX)
• Small cuts, scrapes and bruises can be life threatening
• 1 in 10, 000 males
• 1 in 100,000,000 females
Common amongst royalty in Europe
Queen Victoria = Carrier
i. How many kids did Victoria have? ________
ii. How many kids were carriers?________ # of kids effected? __________
iii. Were any girls affected by the disorder?______ Boys? _____ How many?_____
92 1
no yes 10
Tay-Sachs Pedigree
??
Turner Syndrome
• Genotype: XO
• Phenotype: – Female – Some women are normal– Many are infertile– do not grow/develop normally, are short
statured.
Klinefelter’s Syndrome
• Genotype: XXY
• Phenotype: – Male– Diminished activity of testes– Reduced fertility
Triplo-X
• Genotype: XXX
• Phenotype: Normal
Hermaphrodites ?!?
• Hermaphrodite: An individual that has all female reproductive parts, and all male reproductive parts
• No such thing in Humans
Hermaphrodites ?!?
• However: XY females are as close as you can get
• Genotype: XY
• Phenotype:– Look like women– Do not have uterus, don’t have periods– Some have testes instead of ovaries
Models have a high % of XY women.
Why?
XY women show some “male-like” features that make them good
models
• Taller than most women
• Chiseled Jaw
• Good Muscle definition
• Don’t have as much body fat
Turner syndrome one X Klinefelter syndrome XXY
Triplo-X (normal)
• What is Turner syndrome?• Turner syndrome describes females who have a common constellation of problems
because they are missing all or part of an X chromosome.• Some will have few, if any, noticeable problems, while others may have many. • Some of these problems include:• short stature • lymphedema (a collection of lymph fluid in the tissues; often causing puffiness of the
hands and feet in newborns) • gonadal failure (resulting in delayed or absent sexual development, infertility) • frequent ear infections • progressive nerve hearing loss • strabismus (wandering or crossed eye) • unusual physical features such as a narrow palate, receding jaw, webbed neck, low
hairline, prominent ears, broad chest, and narrow fingernails and toenails that point upwards
• structural abnormalities of the heart and/or the aorta (the main vessel carrying blood away from the heart)
• structural abnormalities of the kidneys • hypothyroidism • multiple moles • non-verbal learning disability
• Patiño is considered by science as an “androgen insensitive.” A fetus of this class develops testes on the eighth week, but the “androgen receptors” are faulty and thus fail to detect the presence of male hormones, even if these are present in the body. In the end, the child is delivered as a girl. Her breasts may enlarge at puberty but she will never menstruate, as her uterus has not developed.
• Approximately one of every 20,000 persons is an androgen insensitive. And about one of every 2,500 females has a single X chromosome. The XY woman, as I shall distinguish her, is actually no different from the XX woman—well, other than she will not physically bear children. There are even a significant number of Western XY women who are into the modeling profession.
• In this new millennium, we must encourage a deeper learning about what determines our gender. A healthy discussion and research on this will aid us in the compassionate understanding of our diversities. Myths that surround gender expression must be set straight all together in the light of scientific explanations. Only by welcoming such evolution in popular beliefs will we be liberated from social condescension.
Turner’s Syndrome Karyotype