Pathophysiology Of Disease - Ch. 2

Front 1

What do the pathophysiologic principles that distinguish disease focus on?

Back 1

They focus on the mechanisms of mutation, inheritance, and molecular pathways from genotype to phenotype

Front 2

Acrocentric

Back 2

Terminal location of the centromere on chromosomes 13, 14, 15, 21, and 22, which contain so-called satellite DNA on their short arms that encodes for ribosomal RNA genes

Front 3

Allelic heterogeneity

Back 3

The situation in which multiple alleles at a single locus can produce on or more disease phenotypes

Front 4

Amorphic

Back 4

Refers to mutations that when present in heterozygous form opposite a nonmutant allele will result in a phenotype similar to homozygosity for loss of function alleles.

Front 5

Ascertainment bias

Back 5

The situation in which individuals or families in a genetic study are not representative of the general population because of the way in which they are identified.

Front 6

What do the pathophysiologic principles that distinguish disease focus on?

Back 6

They focus on the mechanisms of mutation, inheritance, and molecular pathways from genotype to phenotype

Front 7

Acrocentric

Back 7

Terminal location of the centromere on chromosomes 13, 14, 15, 21, and 22, which contain so-called satellite DNA on their short arms that encodes for ribosomal RNA genes

Front 8

Allelic heterogeneity

Back 8

The situation in which multiple alleles at a single locus can produce on or more disease phenotypes

Front 9

Amorphic

Back 9

Refers to mutations that when present in heterozygous form opposite a nonmutant allele will result in a phenotype similar to homozygosity for loss of function alleles.

Front 10

Ascertainment bias

Back 10

The situation in which individuals or families in a genetic study are not representative of the general population because of the way in which they are identified.

Front 11

Autosomal

Back 11

Located on chromosomes 1-22 rather than X or Y

Front 12

CpG island

Back 12

A segment of DNA that contains a releatively high density of 5' -GC- 3' dinucleotides. Such segments are frequently unmethylated and located close to ubiquitously expressed genes.

Front 13

Dictyotene

Back 13

The of of prophase during female meiosis I in which fetal oocytes are arrested prior to ovulation.

Front 14

Dominant

Back 14

A pattern of inheritance of mechanism of gene action in which the effects of a variant allele can be observed in the presence of a nonmutant allele.

Front 15

Dominant negative

Back 15

A type of pathophysiolic mechanism that occurs when a mutant allele interferes with the normal function of the nonmutant gene product.

Front 16

Dosage compensation

Back 16

Mechanism by which a difference in gene dosage between 2 cells is equalized. For XX cells, decreased expression from one of the 2 X chromosomes results in a concentration of gene product similar to an XY cell.

Front 17

End product deficiency

Back 17

A pathological mechanism in which absence or reduction in the product of a particular enzymatic reaction leads to disease.

Front 18

Epigenetic

Back 18

Refers to a phenotypic effect that does nto depend on genotype. DNA methylation that occurs during gametogenesis can affect gene expression in zygotic cells, but the pattern of methylation can also be reversed in subsequent generations and thus does not affect the genotype

Front 19

Expressivity

Back 19

The extent to which a mutant gentoype affects the phenotype; a quantitative measure of a disease state that may vary from mild to severe but is never completely absent.

Front 20

Fitness

Back 20

The likelihood tha an individual who carries a particular mutant allele will produce progeny tha talso carry the allele

Front 21

Autosomal

Back 21

Located on chromosomes 1-22 rather than X or Y

Front 22

CpG island

Back 22

A segment of DNA that contains a releatively high density of 5' -GC- 3' dinucleotides. Such segments are frequently unmethylated and located close to ubiquitously expressed genes.

Front 23

Dictyotene

Back 23

The of of prophase during female meiosis I in which fetal oocytes are arrested prior to ovulation.

Front 24

Dominant

Back 24

A pattern of inheritance of mechanism of gene action in which the effects of a variant allele can be observed in the presence of a nonmutant allele.

Front 25

Dominant negative

Back 25

A type of pathophysiolic mechanism that occurs when a mutant allele interferes with the normal function of the nonmutant gene product.

Front 26

Autosomal

Back 26

Located on chromosomes 1-22 rather than X or Y

Front 27

CpG island

Back 27

A segment of DNA that contains a releatively high density of 5' -GC- 3' dinucleotides. Such segments are frequently unmethylated and located close to ubiquitously expressed genes.

Front 28

Dictyotene

Back 28

The of of prophase during female meiosis I in which fetal oocytes are arrested prior to ovulation.

Front 29

Dominant

Back 29

A pattern of inheritance of mechanism of gene action in which the effects of a variant allele can be observed in the presence of a nonmutant allele.

Front 30

Dominant negative

Back 30

A type of pathophysiolic mechanism that occurs when a mutant allele interferes with the normal function of the nonmutant gene product.

Front 31

Founder effect

Back 31

One of several possible explanations for an unexpectedly high frequency of deleterious gene in a population. If the population was founded by a small ancestral group, it may have, by chance, contained a large number of carriers for deleterious gene

Front 32

Gamete

Back 32

The egg or sperm cell that represents a potential reproductive contribution to the next generation. Gametes have undergone meiosis and so contain half the normal number of chromosomes found in zygotic cells

Front 33

Gene Dosage

Back 33

The principle that the amount of product expressed for particualr gene is proportionate to the number of gene copies present in a cell

Front 34

Genetic anticipation

Back 34

A clinical phenomenom in which a phenotype observed in individuals carrying a deleterious gene appears more severe in successive generations. Possible explanations include ascertainment bias or a multipstep muational mechanism such as expansion of triplet repeats

Front 35

Haplotype

Back 35

A set of cloesely lined alleles that are not easily separated by recombination; often refers to DNA sequence alterations such as restriction fragment length polymorphisms

Front 36

Hemizygous

Back 36

A term referring to the presence of only one allele at a locus, either because the other allele is deleted or because it is normally not present, eg, X-linded genes in males

Front 37

Heterochromatin

Back 37

One of the two alternaitve forms of chromasomal material (the other is euchromatin) in which chromosamal DNA is bound to proteins and condensed. Heterochromatin is highly condensed and usually does not contain gnes that are activly transcribed

Front 38

Heteroplasmy

Back 38

The mixture of mutant and nonmutant mtDNA molecules in a single cell.

Front 39

Heterozygote advantage

Back 39

One way to explain an unexpectedly high frequency of recessively inherited mutation in a particular population. During recent evolution, carriers (ie, heterozygotes) are postulated to have had a higher fitness than homozygous nonmutant indidividuals

Front 40

Heterozygous

Back 40

Having two alleles a tthe same locus that are different.

Front 41

Homozygous

Back 41

Having two alleles at the same locus that are the same

Front 42

Hypermorphic

Back 42

Refers to a mutation tha has an effect similar to increasing the number of normal gene copies per cell

Front 43

Hypomorphic

Back 43

Refers to a mutation that reduces but does not eliminate th activity of a particular gene product

Front 44

Imprinting

Back 44

Most commonly, the process wheeby expression of a gene depends on whether it is transmitted through a female or male gamete

Front 45

Linkage disqeuilibrium

Back 45

A condition in which cetain combinations of closely linked alleles are present in frequencies no predicted by their individual frequency

Front 46

Locus heterogeneity

Back 46

A situation in which mutations of different genes produce similar or identical phenotypes. Also referred to as genetic heterogeneity

Front 47

Mendelian

Back 47

A form of inheritance tha obeys Mendel's law, ie, autosomal dominant, autosomal recessvie, X-linked dominanc or X-linked recessive.

Front 48

Mosaicism

Back 48

A situation in which a genetic alteration is present in some but not all the cells of a single individual. In germline or gonadal mosaicism, the alteraion is present in germ cells but not somatic cells. In somatic mosaicism, the genetic alteraion is present in some but not all of the somatic cells ( and is gnerally not present in the germ cells)

Front 49

Monosomy

Back 49

A reduction in zygotic cells from two to one in the number of copies for a particular chromosomal segment or chromosome

Front 50

Neomorphic

Back 50

Refers to a mutation that imparts a novel function to its gene product and consequently results in a phenotype distinct from an alteration in gene dosage.

Front 51

Nondisjunction

Back 51

Fialure ot two homologous chromosomes to separate, or disjoin at meaphase of meiosis II or mitosis

Front 52

Penetrance

Back 52

IN a single individual of a variant genotype, penetrance is qualitative all or non phenomemnom with respecgt to whether or not defined phenotypic criteria are present. In a population, reduced penetrance refers to the likelihood that an individual of a varieant genotype cannot be recogneezed accoriding to the same phenotypic criteria

Front 53

Phenotypic heterogeneity

Back 53

The situation that obtains when mutations of a single gene produce mutltiple different phenotypes

Front 54

Postzygotic

Back 54

A mutational event that occurs after fertilization and that commly gives rise to mosaicism

Front 55

Premutation

Back 55

A mutational event that occurs after fertilization and that commly gies rise to mosaicism