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71 Cards in this Set
- Front
- Back
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Why is standard nomenclature of genetic history needed?
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For universal communication between doctors and record keeping in the medical record
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How many generations of history must you take?
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3 minimum
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What is a pedigree?
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It is a chart of genetic history over several generations
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Who is the pedigree used by?
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Physicians, lawyers, counslers
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Why use a pedigree chart?
(2 things specifically) |
To make patterns of inheritance apparent
To calculate, probabilities of inheritance. |
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What do 2 horizontal lines connecting two individuals horizontally on a pedigree chart mean?
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It means they are biological relations (first cousins or similar)
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A half filled circle or square means what in relation to the pedigree chart?
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It means a carrier of a trait
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What would an arrow on a pedigree chart pointing an one individual mean?
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This is the the individual that started the need for the pedigree chart to be created
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Why are physicans concerned with biological relations marrying one another and having offspring?
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It increases the likelihood of a autosomal recessive disease being passed on to the offspring.
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The further away in generations you are from a carrier or afflicted person, the _________ the risk of inheritance.
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Lower
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An autosomal disease doesn't appear in every generation?
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False, it is in every generation
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How can an unaffected family member of an autosomal dominant disease family pass the disease to their children?
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They don't show penetrance of the phenotype and thus they have the trait but simply don't show it. Their offspring does express it fully however.
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Are autosomal dominant conditions influenced by gender?
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No, they are independent entirely
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What are the 3 examples given of autosomal dominant disease for genetics class?
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Huntington's, Myotonic dystrophy, and osteogenesis imperfecta
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Osteogenesis imperfecta is a disorder in the production of what protein?
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Collagen
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Myotonic dystrophy is a disorder of producing what protein?
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Protein kinase
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What repeat sequence is indicative of huntington's disease?
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Repeats of CAG
(Greater than 50 repeats) |
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Can cancer be related to autosomal dominant traits?
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Yes, it gives a predisposition to developing cancer.
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What is the second hit hypothesis?
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Inheritance of the autosomal dominant trait which is mutated followed by the other recessive allele being mutated to create a cancer.
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What is a trinucleotide expansion disorder?
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A disorder that involves the genetic code having a repeat that destablizes the DNA
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Where are the repeats in trinucleotide expansion disorders located?
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Often in the UTRs.
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What is an example of a disease given that has a trinucleotide expansion in the 3' UTR?
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Myotonic hypertrophy
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What is the nucelotide repeat in myotonic hypertrophy that causes the disease?
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CTG
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What is the risk of inheriting an autosomal recessive disease?
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25%
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Why do autosomal recessive diseases show up more in countries that have arranged marriages?
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The higher level of consanguineous marriages.
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Autosomal recessive diseases often go after cellular metabolism pathways?
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True
Ex: phenylketonuria |
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Lysosomal storage disease is what type of genetic disorder?
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Autosomal recessive disease
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An X-linked dominant will affect just one gender?
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No, it affects both genders
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What percentage of children will be affected if a mother is a heterozygote?
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50% of children
(All children will be affected if the mother is homozygote) |
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What is CHILD syndrome?
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It is an acronym for a disease involving cholesterol production.
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What very important gene is found on the Y chromosome that is needed for maleness?
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The testis determining factor
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The SRY gene is also known as what?
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Testis determining factor
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What does the SRY gene produce?
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A DNA binding protein that activates certain transcription factor for activation of male traits.
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The transcription factors activate the production of the sex cords. What do the sex cords become?
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The seminiferous tubules
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Following the formation of the testis from the seminiferous tubules, what 2 compounds start being made by the undifferentiated gonads?
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Testosterone and Mullerian inhibiting substance
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Are females affected by XLD?
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Yes, due to random inactivation of the X-chromosome some cells will be affected in a heterozygote.
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Are both genders affected by mitochondrial disorders?
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Yes, they both are.
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What is genetic heterogeneity?
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Different mutations in different alleles or the same allele but different site can cause the same or similar phenotype
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What are the 2 types of genetic heterogeneity?
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Locus
Allelic |
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What is genetic anticipation?
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Dominant inherited diseases that over generations manifest earlier and earlier with increasing severity with each generation.
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Do multifactorial inheritance diseases follow Mendelian mode of inheritance?
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No
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What 2 broad factors contribute to complex inheritance diseases?
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Genetic and
Non-genetic |
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How many autosomal recessive diseases is it estimated that we carry?
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13-16 disease
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What is heritability?
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It is the estimate of phenotypic variance associated with genetic factors.
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Polygenic inheritance shows what normal statistical curve?
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The bell shaped curve
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Heritability describes the likelihood that multiple genes will come together to give a disease phenotype in a complex inheritance pattern?
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True
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What is a continuous trait?
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It is a trait that everyone has or demonstrates. Such as height or hair color
(You can chart them on a bell shaped curve and find a mean height) |
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What is a discontinuous trait?
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These are traits that not everyone has.
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What is a threshold trait?
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These are people that are outliers (extreme combination of genes) on the bellshaped curve + bad environment leads to disease state.
(not the same curve as the continuous trait curve) |
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Threshold traits are found how many standard deviations from normal?
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2 deviations
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How is heritability calculated?
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Using twins with the same genetic code and designing natural experiment to look at the effect of environment on gene code.
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What chromosome is cleft lip and palate related to?
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13
(Trisomy 13) |
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At what time period, does the filtrum joint?
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3-4 weeks
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What are the 2 broad forms of CL/P
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Non-syndromic
Syndromic |
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Can CL/P be bilateral?
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Yes, 20% of cases
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Which side is CL/P more common on?
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Left
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What ethnicities are CL/P most likely in?
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Caucasian and asian
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What is the background level of CL/P?
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0.1%
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What is the risk of recurrence for CL/P?
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3-7%
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Genetic loading favors unilateral or bilateral clefting?
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Bilateral
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What is the carter effect?
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The fact that the rarer sex in a population has a higher genetic load for CL/P.
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The chance of having CL/P if you have a sibling with it is 25%?
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False, it is much lower because it is not Mendelian.
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What big factor will define what the outcome of cleft lip repair will be?
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The underlying cause.
Trisomy 13 has very low good outcome. |
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Classification of NTD is broadly defined as:
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Open or closed
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Generally, neurological elements ______________ to NT lesion will be damaged.
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Below
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Are NTD independent of other conditions/syndromes?
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No, there are syndromes such as trisomy 13 or trisomy 18 that have attached spina bifida.
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Can spina bifida be familial?
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Yes.
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What vitamin supplement can drastically reduce NTD?
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Folic acid addition can greatly reduce NTD
(50-70% of NTD can be prevented by folic acid) |
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Why does folic acid need to be given immediately to any women trying to become pregnant?
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The NT forms early so if the woman waits until she is late then she will probably have lost the time frame.
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Why does the government require grains to be fortified?
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To make sure the average population has sufficient folic acid. It is not enough for pregnant women.
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Before implantation, toxins such as lead and alcohol are most dangerous.
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False, only after implantation
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