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Genetics - Pedigrees and Genetic Disorders
Transcript of Genetics - Pedigrees and Genetic Disorders
A way of tracking genetic relationships
shaded: expresses phenotype
unshaded: no phenotype
An example of an genetically unhealthy pedigree (why?)
Modern genetic testing can detect genotype directly
A few points to keep in mind
Very few traits are inherited in strictly Mendelian patterns.
From an evolutionary perspective, traits that confer fitness in some circumstances can be detrimental in others.
Widow's Peak shows a dominant inheritance pattern
Examples of other Dominant Conditions
One of several forms of Dwarfism in humans.
Affects cartilage formation and bone growth.
Lethal in homozygous condition
One of several forms of Gigantism in humans.
Develops from an overactive pituitary gland
Can lead to serious health complications
Andre The Giant
Results from an abnormally large huntingtin protein.
Leads to degeneration of the nervous system.
Symptomatic and lethal in middle age.
Attached earlobes show a a recessive inheritance pattern
Examples of other Recessive Conditions
A mutation in the melanin production pathway.
Can be associated with vision problems, increased photosensitivity.
Seen in many different animals
An inability to digest the amino acid phenylalanine (common in many foods and artificial sweeteners).
Untreated can lead to mental retardation.
Can be managed with diet regulation.
A defect in chloride ion membrane channel proteins, leads to a buildup of stick mucus
Has many symptoms, particularly in the respiratory and digestive system.
Must be intensively managed
Death usually by age 50.
Most common sex-linked inheritance pattern in humans.
Tend to show up in males due to hemizygosity.
A defect in the proteins involved in blood clotting.
2 different forms are X-linked recessive conditions.
Can lead to death from hemorrhage (not typical in modern times).
Red-Green Color Blindness
A defect in the proteins that detect particular wavelengths of light.
Harmless...unless you want to be a pilot.
Not particularly common...
...but make sure you can spot it on a pedigree
Even less common than X-linked Dominant (the Y chromosome has almost no genes on it).
Duchenne Muscular Dystrophy
Due to an abnormality in the dystrophin protein.
Early onset muscle degeneration disease.
Symptoms appear by age 6, terminal by mid-20's
Inheritance of Hemophilia in a European Royal Lineage.
The Dystrophin protein is encoded in the longest gene in the human genome (2.4 MB)
An example of a vision test given to children to determine color-blindness.
What % of the F1 generation was affected?
Is there any evidence that it is possible to be a carrier for this disease?