Looking at patterns of inheritance within a particular family or population to track an inherited disease/disorder.
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What are the four main patterns of inheritance?
Autosomal dominant, autosomal recessive, X linked recessive and Y linked dominant.
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How are disease/disorder reservoirs formed?
Inherited diseases that are due to recessive alleles can be carried in the population due to heterozygotes showing no symptoms. Then homozgous offspring show symptoms.
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What does propositus mean?
This is the person whom the pedigree is being investigated.
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What does consanguineous mean?
This is a closed blood mating e.g. cousins, brother and sister.
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What type of inheritance is Huntington's Chorea?
Is an autosomal dominant gene. Both sexes are equally as affected and sufferers are heterozygotes.
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What type of inheritance does polydactyl have?
Dominant mode of inheritance
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What type of inheritance is fibrocystic disease?
This is an autosomal recessive gene and affected offspring are homozygous.
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How do the human sex chromosomes differ?
Both have a pseudoautosomal region, but X chromosomes are larger and contain more information than the Y chromosome. The Y chromosome has an SRY gene which is important for testes formation.
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How was sex linked inheritance discovered?
Morgan found white eyed male flies in a red eye fly population. Only the males had the white eye so showed a recessive characteristic on the X chromosome as females did not show the effect.
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What are examples of human sex linked inheritance?
Haemophilia, Duchene Muscular Dystrophy
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What is mitochondrial inheritance?
The mitochondrial genome inherited from the mother. Disorders involving the mitochondria are passed on to all offspring.
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What is mitochondrial disease?
When mitochondria are inoperative in certain cells, causing cell death.
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What does MELAS cause?
Seizures, migranes, strokes, high lactate content in CSF and brain tissue.
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What pattern does an autosomal recessive disorder create on a pedigree diagram?
The disorders appear in progeny of unaffected parents, and the affected progeny are both male and female.
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What pattern does an autosomal dominant disorder create on a pedigree diagram?
The pheontype appears in every generation of the pedigree. There is equal representation of both sexes being affected.
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What is autosomal polymorphism?
The coexistence of two or more common phenotypes of a character.
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What pattern does an X linked recessive disorder create on a pedigree diagram?
There will be a higher proportion on males with the phenotype, none of the affected males offspring will be affected but the daughters will be carriers.
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What pattern does an X linked dominant disorder create on a pedigree diagram?
The affected males pass the condition to daughters but not sons. Heterozygous females will pass condition to half their offspring.
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What do inheritance patterns with unequal representation of phenotypes in males and females show?
The genes for the phenotype are on one of the sex chromosomes.
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Other cards in this set
Card 2
Front
What are the four main patterns of inheritance?
Back
Autosomal dominant, autosomal recessive, X linked recessive and Y linked dominant.
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