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59 Cards in this Set
- Front
- Back
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Define "familial."
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Running in the family (genetic or non-genetic).
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Define "congenital."
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Present at birth (genetic or non-genetic).
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Define "genetic."
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Having basis in genetic material.
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Define "heritable."
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Capable of being inherited (genetic or non-genetic).
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Define "acquired."
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Not having basis in genetic material.
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Define "sporadic."
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Having little or no recurrence risk (genetic or non-genetic).
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Define "proband."
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The affected individual in the family.
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Define "consultand."
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The person requesting genetic counseling.
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Define "genotype."
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The genetic constitution, a set of specific alleles at a gene locus in an individual.
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Define "phenotype."
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The expression of a gene or genes plus environment resulting in physical namifestations for an individual.
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Of DNA and chromosomes, which can one can only be obtained from actively dividing material?
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Chromosomes.
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What is heterochromatin?
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The parts of the chromosomes that are either devoid of genes or have inactive genes.
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What is euchromatin?
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The parts of the chromosomes that contain the coding regions of genes.
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What letter is used to refer to the long arm of the chromosome? The short arm?
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q; p.
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What is a hemizygote?
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A locus where there is only one allele present.
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What is a compound heterozygote?
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An individual with two different mutant alleles at a given locus.
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What is the prevalence of congential birth defects?
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2-3%.
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What is the prevalence of chromosomal abnormalities at birth?
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0.5%.
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When dealing with genetic disease evident before age 25, the prevalence of single gene disorders (Mendelian) is ?/1000.
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3.6.
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When dealing with genetic disease evident before age 25, the prevalence of multifactorial diseases is ?/1000.
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47.
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What percentage of couples are infertile?
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10%.
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What are some things to know about the proband when taking a family history?
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What is the diagnosis? Are they a phenocopy? What is the proband's health and physical status?
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What are some things to know about the proband's family when taking a family history?
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Miscarriages, stillborn infants, neonatal deaths, other family members with similar conditions, ethnic background, consanguinity within the family.
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How do you determine how many "degrees" away a relative is?
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The number of steps down the line they are.
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Male-to-male inheritance is characteristics of what pattern of inheritance?
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Autosomal dominant.
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What is variable expressivity?
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The variety in expression of the trait in affected individuals (mild/severe).
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What is heterogeneity?
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The presence of different alleles or genes resulting in a similar phenotype.
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What is a phenocopy?
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A mimic of a phenotype which is caused by a gene, but which is actually environmental.
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What is mosaicism?
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The presence of two or more genetically distinct cell lines in an individual derived from a single zygote due to a postzygotic mutation or nondisjunction.
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What effects can gonadal mosaicism have on probabilities of defects?
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If one child has a mutation, subsequent children are at higher risk for the same mutation.
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What is heteroplasmy?
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A mixture of normal and mutant mitochondrial DNA.
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What is homoplasmy?
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The presence of only normal or mutant mitchondrial DNA.
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What is polygenic inheritance?
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A situation where multiple genes play a role in determining a phenotype.
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With multifactorial traits, how do risks compare for first- and second-degree relatives of affected individuals?
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They are much less for second-degree relatives.
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Define "genetic isolates."
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A situation where a population is geographically isolated.
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Define "founder effect."
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A situation where the initial settlers of a population carried a certain allele.
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Define "assorted mating."
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Choice of mates based on a certain trait.
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What is gene flow?
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Movement of populations affecting allele frequency.
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What population is most at risk for cystic fibrosis?
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Caucasians.
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What population has the highest incidence of the ADH2 (alcohol dehydrogenase) allele?
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The Japanese.
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What 2 populations have the lowest activity of the lactase allele?
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Africans and Asians.
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What population has the highest rate of sickle cell disease?
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Africans.
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What population has the highest rate of Tay Sachs disease?
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Ashkenazi Jews.
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What population has the highest rate of myotonic dystrophy?
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The people of the Lac St. Jean area.
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How are affected individuals designated on a pedigree chart?
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Shading.
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How are pregnant individuals designated on a pedigree chart?
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A "P" inside the symbol.
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How are stillborn children designated on a pedigree chart?
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A slash through the normal symbol.
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How are spontaneous abortions designated on a pedigree chart?
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The symbol used is a triangle.
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How are planned abortions designated on a pedigree chart?
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The symbol used is a triangle with a slash through it.
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How are divorces designated on a pedigree chart?
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A slash on the line between the partners.
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How are siblings of unspecified gender designated on a pedigree chart?
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A diamond (with the number of siblings written inside, if there's more than one).
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How are consanguinous couples designated on a pedigree chart?
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A double line between them.
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How are monozygous twins designated on a pedigree chart?
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They are drawn from the same drop-down line at diagonals, with a horizontal line connecting the diagonal lines.
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How are dizygous twins designated on a pedigree chart?
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They are drawn from the same drop-down line at diagonals.
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How is the lack of children by choice or for unknown reasons designated on a pedigree chart?
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A line coming down from the individual, with a single slash at the end.
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How is infertility for known reasons designated on a pedigree chart?
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A line coming down from the individual, with a double slash at the end and the cause written beneath.
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How are adopted children designated on a pedigree chart?
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Children adopted in are put in brackets and connected by a dotted line; children adopted out are drawn as normal descendants.
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How is the consultand designated on a pedigree chart?
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With an arrow.
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How is the proband designated on a pedigree chart?
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With an arrow and a "P."
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