Transcript Genetic Inheritance

Groups for Genetics
Group #1
DeCoste, Victoria
MacDonald, Mary
Denaro, Chelsea
Sibley, Nicole
Allen, Jasmine
Croft, Lauren
Mombourquette, Shelbie
Group #4
Roach, Christian
Downey, Erica
Carroll, Kathleen
Myers, Jamie
Festeryga, Deirdre
Mattie, Joni
Group #7
Maciel, Analiese
Smith, Shannalee
Murphy, Jillian
Taylor, Emma
Hughes, Tanner
Redden, Julie
Group #2
Gillis, Carly
Douglas, Patti
Visentin, Christina
Smith, Jennifer
Downing, Allison
Thompson, Mary Catherine
Group #3
Bernas, Alex
MacDonald, Brittany
Williams, Kailyn
Baisley, Ashley
Burns, Laura
Stevenson, Mason
Group #5
Savary, Murphy
Smith, Maggie
Schofield, Katelyn
Gougeon, Felipe
Gillis, Erin
Clarke, Lauren
Group #8
Poirier, Baillie
Hum, Katherine
Johnson, Christeen
Eisan, Brianna
Hingston, Olivia
Cunningham, Cassy
Group #6
Gillis, Kenzie
Fraser, Kayla
Davis, Savannah
Gillis, Heather
MacAulay, Alyssa
Piché, Angela
Group #9
Burke, Carrie
MacDougall, Abbey
Berry, Rachel
McLellan, Bailey
Corcoran, Courtney
Livingstone, Annie
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Patterns of Genetic Inheritance
Rels 300 / Nurs 330
7 January 2016
GENES ON CHROMOSOMES
23 pairs of chromosomes
• 1 out of each pair comes
from maternal ovum
• 1 out of each pair comes
from paternal sperm
• 22 are matched pairs
• x and y are sex
chromosomes
• males have 1 x and 1 y
• females have 2 x’s
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X-LINKED INHERITANCE
Examples of X-linked recessive disorders:
Fragile X; Hemophilia; Muscular
Dystrophy
Examples of X-linked dominant disorders:
Rett syndrome (very rare)
The mother has 2 X chromosomes
• her ova will have either an unaffected
gene OR an affected gene
The father has one X and one Y
chromosome
• his sperm will have either an X or a Y
chromosome
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Fragile X syndrome
Common traits & symptoms:
• Mild to severe intellectual disabilities
• Emotional and behavioural problems
What does it look like? https://public.ornl.gov/site/gallery/originals/ChromX.jpg
• A male child inherits an X from his mother and a Y from
his father; if the X is fragile, he will be affected
• A female child inherits an X from her father and another
X from her mother (who has 2 Xs)
• A girl (who has 2 Xs) may have one normal X and one
fragile X; not likely to be affected
• If a girl inherits 2 fragile Xs, she will be severely affected
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Females have an X chromosome from father and an X
chromosome from mother;
Males have an X and a Y chromosome
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Turner’s Syndrome &
Klinefelter’s Syndrome
Turner’s Syndrome:
• affects 1 in 3000 girls
• 1 (or part of one) of the X
chromosomes is missing
• only 45 chromosomes
total
Klinefelter’s Syndrome:
• affects 1 in 700 boys
• extra X chromosome
(XXY) - 47 chromosomes
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RECESSIVE PATTERN INHERITANCE
Recessive pattern illnesses: sickle cell;
Tay-Sachs; hemochromatosis;
thalassemia; PKU; PKD
Cystic fibrosis: defect in a gene located on
chromosome 7
(https://public.ornl.gov/site/gallery/originals/Chrom07.jpg )
• pulmonary and gastrointestinal disease
• if neither mother nor father have cystic
fibrosis, they may still be carriers of 1
faulty gene
• if only mother or father have 1 faulty
gene, then no child will have cystic
fibrosis; but child may still be carrier of
disease
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Recessive Inheritance
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DOMINANT PATTERN INHERITANCE
Dominant pattern illnesses: Marfan;
neurofibromatisis; Alzheimer
Huntington’s disease: a degenerative
neurological disorder
• faulty gene on chromosome 4
(https://public.ornl.gov/site/gallery/originals/Chrom04.jpg)
• if mother or father have 1 faulty gene,
she or he WILL develop Huntington’s
disease – but not until age 40 – 50
• if affected parent passes on faulty
gene, then child will also be affected
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CHROMOSOMAL ABNORMALITIES
Kinds of abnormalities:
• part or all of a single
chromosome may be missing
• numerical abnormality - a
sperm or ovum may have an
extra chromosome (24) or lack
a chromosome (22), e.g.
Turner Syndrome
• Extra chromosome material,
e.g. Down Syndrome (Trisomy
21)
[https://public.ornl.gov/site/gallery/original
s/Chrom21.jpg ]
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• structural abnormality rearrangement or loss of
genetic material
• e.g., deletions,
duplications, inversions,
ring formations and
translocations of
chromosome sections
• Fragile X syndrome - a
weakened or fragile site
on the X chromosome
[https://public.ornl.gov/site/gallery
/originals/ChromX.jpg ]
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Examples of Genetic
Conditions & Diseases
Condition
Pattern of
Inheritance
Affected
Gene(s)
Symptoms &
Incidence
Testing &
Screening
Fragile X
Syndrome
Cystic Fibrosis
D / B Muscular
Dystrophy
Down
Syndrome
Alzheimer
Disease:
Sporadic
Familial
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Ethical Issues:
Privacy and Confidentiality
• If you have a history of Huntington’s Disease in
your family, should you have genetic testing to
see if you will develop the illness?
• If you do have genetic testing, should you tell
your siblings or partner the results of your
testing?
• Should you be forced to submit to prenatal
genetic testing before you decide to have
children?
YES
NO
UNDECIDED
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Ethical Issues: Insurability
• If you are applying for life insurance, and you have a
history of breast or ovarian cancer in your family, should
you be compelled to have genetic testing for the BRCA1
or BRCA2 genes?
• If you have had this testing, must you tell the company?
• May they deny life insurance to you?
• Should life insurance companies have access to your
genetic information?
YES
NO
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UNDECIDED
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Ethical Issues: Employability
• Should an employer have the right to know
your family history, including genetic disease,
prior to offering you employment?
• Should an employer have the right to deny
employment to someone with a susceptibility to
a genetic condition?
• Should employers have access to your genetic
information?
YES
NO
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UNDECIDED
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Ethical Issues: Childbearing
• Should all pregnant women have prenatal
testing?
• If a woman decides to continue a pregnancy
involving a fetus with a genetic disorder, should
she consider aborting the fetus?
• If she continues with the pregnancy, should she
expect social supports in caring for an affected
infant and child?
YES
NO
UNDECIDED
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Take another look at your list of
genetic conditions & diseases:
Which of these ethical issues would be of concern
to a person with the genetic condition you have
investigated:
• Privacy and Confidentiality
• Insurability
• Employability
• Childbearing
What additional ethical issues or dilemmas might
you expect to face if you were living with a
diagnosed genetic condition?
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• Class notes continued on slides
for January 13th
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