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59 Cards in this Set

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