Definitions + Misc. Flashcards Preview

PBR: Genetics > Definitions + Misc. > Flashcards

Flashcards in Definitions + Misc. Deck (26)
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1
Q

Congenital

A

A condition or anomaly present at birth.

2
Q

Hereditary

A

Refers to conditions that are genetically transmitted from parents to offspring.

3
Q

Familial

A

Refers to conditions that “cluster” in families and can include genetic as well as nongenetic (e.g. ADHD, HTN) conditions.

4
Q

Genotype

A

The genetic makeup of an individual, or different forms of a gene at a given locus on a chromosome.

5
Q

Phenotype

A

The observed expression (physical, biochemical, or physiological) of a genotype.

6
Q

Penetrance

A

The ability of a known disease-causing genotype to exhibit the disease phenotype.

7
Q

Describe the penetrance for a condition in which 10% of the population with the disease-causing genotype do not go on to develop the disease.

A

The penetrance in this situation would be 90%.

8
Q

Variable expressivity

A

When individuals who have the same genetic condition/genotype have varying degrees of the associated phenotype.

9
Q

Genomic Imprinting

A

Imprinting turns of selected genes, so the expression of the gene depends on whether the gene was inherited from the mother or the father.

10
Q

Pleiotropic

A

Refers to genes that produce many effects. An example is Marfan syndrome, which can affect the eyes, cardiovascular system, and skeletal system.

11
Q

Mosaicism

A

The presence of ≥2 genetically different sets of cells in the same person caused by an error in mitosis.

12
Q

Heterozygous

A

Refers to the presence of two different alleles at a gene locus on a pair of homologous chromosomes.

13
Q

Homozygous

A

Refers to the presence of two identical alleles at a gene locus on a pair of homologous chromosomes.

14
Q

Autosome

A

Refers to all chromosomes except the X and Y chromosomes.

15
Q

Nondisjunction

A

Occurs when homologous chromosomes or chromatids fail to separate, resulting in an abnormal number of chromosomes in the daughter cells.

16
Q

Aneuploidy

A

Refers to the presence of an abnormal number of chromosomes in a cell.

17
Q

Complex

A

Anomalies of several different structures that are near each other during embryonic development (ex: limb-body wall complex)

18
Q

Association

A

Anomalies seen together that do not have a known single genetic or developmental etiology (ex: VACTERL)

19
Q

Syndrome

A

A recognizable pattern of structural defects, due to a known single genetic etiology, with a predictable natural history that remains relatively consistent across unrelated patients (ex: Cornelia de Lange, Williams)

20
Q

Balanced Translocation

A

An even exchange of genetic material between chromosomes, resulting in no extra or missing genes.

21
Q

Unbalanced Translocation

A

An uneven exchange of genetic material between chromosomes, resulting in extra or missing genes.

22
Q

Sequence

A

A pattern of multiple anomalies caused by a single identifiable even in development (ex: Pierre Robin sequence)

23
Q

What is multifactorial inheritance?

A

Genetic disorders which are due to multiple genetic and environmental factors rather than a “single gene” mutation.

24
Q

What (7) factors suggest multifactorial inheritance has occurred?

A

There is no discernable Mendelian inheritance pattern; recurrence risk increases as the number of affected individuals in the family increases; recurrence risk is higher if the affected individual is a member of the less commonly affected sex; recurrence risk is higher if the individual has a more severe form/case; recurrence risk drops dramatically as the degree of familial relationship decreases from the affected individual; recurrence risk correlates with the prevalence in the general population; and environmental factors play a role.

25
Q

Are dizygotic twins more likely, less likely, or equally likely to have genetic traits similar to those of a nontwin sibling?

A

From a straightforward genetic perspective, dizygotic twins are no more similar than nontwin siblings.

26
Q

Name 4 diseases or abnormalities that are more likely to be concordant in monozygotic than dizygotic twins.

A

Autism (60% vs 0%), Cleft lip/palate (38% vs 8%), clubfoot (32% vs 3%), and spina bifida (72% vs 33%).