MedGen Terms (T&T) Flashcards Preview

Genetic Counseling > MedGen Terms (T&T) > Flashcards

Flashcards in MedGen Terms (T&T) Deck (289)
Loading flashcards...
1
Q

The boundary between the 3’ end of an intron and the 5’ end of the following exon

A

Acceptor (or 3’) splice site

2
Q

A type of chromosome with the centromere near one end

A

Acrocentric

3
Q

Chromosomes 13, 14, 15, 21, 22

A

Acrocentric chromosomes

4
Q

One of the alternative versions of a gene or DNA sequence at a given locus

A

Allele

5
Q

An oligonucleotide probe synthesized to match a particular DNA sequence precisely and allow the discrimination of alleles that differ by only a single base

A

Allele-specific oligonucleotide (ASO)

6
Q

The same or similar phenotypes are caused by different mutant alleles

A

Allelic heterogeneity

7
Q

The ability of a test to perform correctly, measure what it is designed to measure

A

Analytic validity

8
Q

Any chromosome number that is not an exact multiple of the haploid number

A

Aneuploidy

9
Q

Birth defects resulting from malformations, deformations, or disruptions

A

Anomalies

10
Q

The progressively earlier onset and increased severity of certain diseases in successive generations of a family

A

Anticipation

11
Q

A three-base unit of RNA complementary to a codon in mRNA

A

Anticodon

12
Q

Programmed cell death

A

Apoptosis

13
Q

A group of abnormalities of unknown etiology and pathogenesis that is seen together more often than would be expected by chance

A

Association

14
Q

Any nuclear chromosome other than the sex chromosomes

A

Autosome

15
Q

A polymorphism maintained in the population by heterozygote advantage, allowing an allele, even if deleterious in the homozygous state, to persist at a relatively high frequency in the population

A

Balanced polymorphism

16
Q

A technique which stains chromosomes in a characteristic pattern, allowing identification of individual chromosomes and structural abnormalities

A

Banding

17
Q

The sex chromatin as seen in female somatic cells, representing an inactive X chromosome

A

Barr body

18
Q

A pair of complementary nucleotide bases, used as the unit of measurement of the length of a DNA sequence

A

Base pair (bp)

19
Q

A mathematical model used to calculate recurrence risk

A

Bayesian analysis

20
Q

The ethical principle of behaving in a way that promotes the well-being of others

A

Beneficence

21
Q

An abnormality present at birth, not necessarily genetic

A

Birth defect

22
Q

Tumor-suppressor genes that are indirectly involved in controlling cellular proliferation by repairing DNA damage and maintaining genomic integrity, protecting from mutations that could lead to cancer

A

Caretaker genes

23
Q

An individual heterozygous for a particular mutant allele; disease is not expressed

A

Carrier

24
Q

The primary constriction on the chromosome, required for normal segregation in mitosis and meiosis

A

Centromere

25
Q

The crossing of chromatid strands of homologous chromosomes, seen at the diplotene of the first meiotic dividion

A

Chiasma

26
Q

An individual composed of cells derived from two genetically different zygotes; an inevitable result of transplantation

A

Chimera

27
Q

The two parallel strands of chromatin, connected at the centromere, that constitute a chromosome after DNA synthesis

A

Chromatids

28
Q

The complex of DNA and proteins of which chromosomes are composed

A

Chromatin

29
Q

A small mass of chromatin containing genes for ribosomal RNA, at the end of the short arm of each chromatid of an acrocentric chromosome

A

Chromosomal satellite

30
Q

One of the threadlike structures in the cell nucleus; consists of chromatin and carries genetic information

A

Chromosome

31
Q

A clinical condition caused by an abnormal chromosome constitution in which there is duplication, loss, or rearrangement of chromosomal material

A

Chromosome disorder

32
Q

A change in the genetic material at the chromosome level

A

Chromosome mutation

33
Q

Refers to the relationship between two sequences that are on the same chromosome

A

Cis

34
Q

The occurrence of clinically different phenotypes from mutations in the same gene

A

Clinical heterogeneity

35
Q

The ability of a test to improve the medical care than an individual receives

A

Clinical utility

36
Q

The ability of a test to detect the disease that the test was designed to detect

A

Clinical validity

37
Q

Both alleles of a pair are expressed in the heterozygous state

A

Codominant

38
Q

A triplet of three bases in a DNA or RNA molecule, specifying a single amino acid

A

Codon

39
Q

The probability that an individual homozygous at a locus received both alleles from one ancestor

A

Coefficient of inbreeding (F)

40
Q

A fluorescence hybridization technique used to compare two different DNA samples with respect to their relative content of a particular DNA segment or segments

A

Comparative genome hybridization (CGH)

41
Q

A pattern of inheritance that is not mendelian, usually results from alleles at more than one locus interacting with environmental factors

A

Complex inheritance/Multifactorial inheritance

42
Q

An individual, or genotype, with two different mutant alleles at the same locus

A

Compound heterozygote

43
Q

Mosaicism present in the placenta but not present in the fetus

A

Confined placental mosaicism

44
Q

Present at birth, not necessarily genetic

A

Congenital

45
Q

Related by descent from a common ancestor

A

Consanguinity

46
Q

A syndrome resulting from a microdeletion of chromosomal DNA extending over two or more loci

A

Contiguous gene syndrome

47
Q

A variation in DNA sequence defined by the presence or absence of a segment of DNA, ranging from 200bp to 2Mb

A

Copy number variant (CNV)

48
Q

If a DNA variant has an allele frequency >1%

A

Copy number polymorphism (CNP)

49
Q

A procedure used in prenatal diagnosis to obtain a sample of fetal blood directly from the placenta

A

Cordocentesis

50
Q

A procedure used in prenatal diagnosis to obtain amniotic fluid

A

Amniocentesis

51
Q

A procedure used for prenatal diagnosis, where fetal tissue for analysis is withdrawn during 10-13wks gestation

A

Chorionic villus sampling (CVS)

52
Q

A measure of correlation that varies from 1 for perfect positive to -1 for perfect negative

A

Correlation coefficient (r); 0 indicating there is no correlation

53
Q

The reciprocal exchange of segments between chromatids of homologous chromosomes

A

Crossover

54
Q

The study of chromosomes

A

Cytogenetics

55
Q

The fetal cells of the chorionic villi that are sampled for karyotyping and DNA analysis

A

Cytotrophoblast

56
Q

The two individual chromosomes formed when a single chromosome composed of paired chromatids separates at the centromere in anaphase of cell division

A

Daughter chromosomes

57
Q

A recognizable pattern of dysmorphic features caused by extrinsic factors that affect the fetus in utero

A

Deformation syndrome

58
Q

the distance between two individuals in a pedigree

A

Degree of relationship

59
Q

The loss of sequence of DNA from a chromosome

A

Deletion

60
Q

A structurally abnormal chromosome with two centromeres

A

Dicentric

61
Q

The process whereby a cell acquires a tissue-specific pattern of expression of genes and proteins and a characteristic phenotype

A

Differentiation

62
Q

The number of chromosomes in most somatic cells

A

Diploid

63
Q

A birth defect caused by destruction of tissue; may be caused by vascular occlusion, a teratogen, or rupture of the amniotic sac with entrapment

A

Disruption

64
Q

Twins produced by two separate ova, separately fertilized

A

Dizygotic twins

65
Q

The molecule that encodes the genes responsible for the structure and function of living organisms and allows the transmission of genetic information

A

DNA

66
Q

An enzyme that can synthesize a new DNA strand by using a previously synthesized DNA strand as a template

A

DNA polymerase

67
Q

A trait phenotypically expressed in heterozygotes

A

Dominant

68
Q

A disease-causing allele, or the effect of such an allele, that disrupts the function of a wild-type allele in the same cell

A

Dominant negative

69
Q

As a consequence of X inactivation, the amount of product formed by the two copies of an X-linked gene in females is equivalent to the amount formed by the single gene in males

A

Dosage compensation

70
Q

An individual who is heterozygous at each of two different loci

A

Double heterozygote (different from compound heterozygote!)

71
Q

Expression of a gene at a time when it is not normally expressed

A

Dyschronic expression

72
Q

Morphological developmental abnormalities, as seen in many syndromes of genetic or environmental origin

A

Dysmorphism

73
Q

A disorder resulting from the interaction of a genetic predisposition to a specific disease with an environmental factor

A

Ecogenetic disorder

74
Q

Expression of a gene in places where it is not normally expressed

A

Ectopic expression

75
Q

A cell derived from the inner cell mass that is self-renewing in culture and can repopulate all the tissues of the embryo

A

Embryonic stem cell

76
Q

The probability that a familial trait will occur in a family member based on observed numbers of affected and unaffected individuals

A

Empirical risk

77
Q

A metabolic disorder resulting from deficiency or abnormality of a specific enzyme

A

Enzymopathy

78
Q

Any factor that can affect gene function without change in the genotype

A

Epigenetic

79
Q

Any chromosome number that is an exact multiple of the number of haploid gamete (n)

A

Euploid

80
Q

A transcribed region of a gene that is present in mature messenger RNA

A

Exon

81
Q

The extent to which a genetic defect is expressed

A

Expressivity

82
Q

Any trait that is more common in relatives of an affected individual than in the general population, whether the cause is genetic, environmental, or both

A

Familial

83
Q

Stage of intrauterine development from weeks 9 to 40

A

Fetal phase

84
Q

FISH

A

flourescence in situ hybridization

85
Q

The probability of transmitting one’s genes to the next generation compared with the average probability for the population

A

Fitness (f)

86
Q

A high frequency of a mutant allele in a population founded by a small ancestral group when one or more of the founders was a carrier of the mutant allele

A

Founder effect

87
Q

Nonstaining gap in the chromatin of a metaphase chromosome (ex:Xq27)

A

Fragile site; Xq27 is the fragile site for Fragile X syndrome

88
Q

A mutation involving a deletion or insertion that is not an exact multiple of three base pairs, and thus changes the reading frame of the gene downstream of the mutation

A

Frameshift mutation

89
Q

A mutation associated with an increase in one or more of the normal functions of a protein

A

Gain of function mutation

90
Q

A reproductive cell with the haploid chromosome number

A

Gamete (ovum or sperm)

91
Q

Tumor suppressor genes that directly regulate cell proliferation

A

Gatekeeper genes

92
Q

A hereditary unit; a sequence of chromosomal DNA required for the production of a functional product

A

Gene

93
Q

The number of copies of a particular gene in the genome

A

Gene dosage

94
Q

A set of genes containing related exons, indicating that the genes have evolved from an ancestral gene by duplication and subsequent divergence

A

Gene family

95
Q

Gradual diffusion of genes from one population to another across a barrier (may be physical or cultural, and may be breached by migration or mixing)

A

Gene flow

96
Q

The characteristic arrangement of the genes on the chromosomes

A

Gene map

97
Q

All the alleles present at a given locus or at all loci in the population

A

Gene pool

98
Q

Treatment of a disease by introduction of DNA sequences that will have a therapeutic benefit

A

Gene therapy

99
Q

Characteristic determined by genes

A

Genetic

100
Q

The 64 triplets of bases that specify the 20 amino acids found in proteins

A

Genetic code

101
Q

The ability of one mutant allele at a locus to correct for the loss of function associated with another allele at the same or another locus, demonstrating that the mutations are not identical

A

Genetic complementation

102
Q

The provision of information and assistance to affected individuals or family members at risk of a disorder that may be genetic, concerning the consequences of the disorder, the probability of developing or transmitting it, and the ways in which it may be prevented

A

Genetic counseling (according to T&T)

103
Q

A defect wholly or partly caused by a gene abnormality

A

Genetic disorder

104
Q

Random fluctuation of allele frequencies in small populations

A

Genetic drift

105
Q

The production of the same or similar phenotypes by different genetic mechanisms

A

Genetic heterogeneity

106
Q

A mutant allele or genetically determined trait that leads to failure to reproduce, though not necessarily to death prior to reproduction

A

Genetic lethal

107
Q

The sum total of death and disease caused by mutant genes

A

Genetic load

108
Q

Testing on a population basis to identify individuals at risk of developing or of transmitting a specific disorder

A

Genetic screening

109
Q

A genotype that determines a phenotype closely similar to that determined by a different genotype

A

Genocopy

110
Q

The complete DNA sequence, containing the entire genetic information, or a gamete, an individual, a population, or a species

A

Genome

111
Q

The chromosomal DNA sequence of a gene or segment of a gene, including the DNA sequence of noncoding and coding regions

A

Genomic DNA

112
Q

The field of genetics concerned with structural and functional studies of the genome

A

Genomics

113
Q

The alleles present at one locus, the genetic constitution of an individual as distinguished from the phenotype

A

Genotype

114
Q

The cell line from which gametes are derived

A

Germline

115
Q

The presence of two or more genetically different types of germline cells, resulting from mutation during the proliferation and differentiation of the germline

A

Germline mosaicism

116
Q

The chromosome number of a normal gamete, with only one member of each chromosome pair

A

Haploid

117
Q

A cause of genetic disease in which the contribution form a normal allele is insufficient to prevent disease because of a loss of function mutation at the other allele

A

Haploinsufficiency

118
Q

A group of alleles in coupling at closely linked loci, usually inherited as a unit

A

Haplotype

119
Q

The law that relates allele frequency to gentoype frequency, used in population genetics to determine allele frequency and heterozygote frequency when the incidence of a disorder is known

A

Hardy-Weinberg law (p^2 + 2pq + q^2)

120
Q

The genotype of an individual with only one representative of a chromosome or chromosome segment, rather than the usual two; refers especially to X-linked genes in the male

A

Hemizygous

121
Q

The fraction of total phenotypic variance of a quantitative trait that is due to genotypic differences

A

Heritability (h^2)

122
Q

The presence of more than one type of mitochondrial DNA in the mitochondria of a single individual

A

Heteroplasmy

123
Q

Any chromosome number other than the normal

A

Heteroploid

124
Q

An individual or genotype with two different alleles at a given locus on a pair of homologous chromosomes

A

Heterozygote

125
Q

A pair of chromosomes, one inherited paternally, the other maternally, that pair with each other during meiosis I, undergo crossover, and separate at anaphase I of meiosis

A

Homologous chromosomes

126
Q

Genes in a single species, or in different species, that have overall similar DNA sequences, that may have related biochemical functions, and that arose from a common ancestral gene

A

Homologous genes

127
Q

The presence of only one type of mitochondrial DNA in the mitochondria of a single individual

A

Homoplasmy

128
Q

An individual or genotype with identical alleles at a given locus on a pair of homologous chromosome

A

Homozygote

129
Q

Genes expressed in most or all cells because their products provide basic functions

A

Housekeeping genes

130
Q

Proteins expressed in virtually every cell that have fundamental roles in the maintenance of cell structure and function

A

Housekeeping proteins

131
Q

A major research project that took place from 1990-2003 and resulted in the sequencing of a representative human genome and the genomes of many model organisms

A

Human Genome Project

132
Q

An abnormality of the placenta in which it grows to resemble a hydatid cyst, associated with very abnormal fetal development

A

Hydatidiform mole

133
Q

Complete mole (karyotype and parental contribution)

A

46,XX karyotype, duplication of the chromosomes of the sperm with no maternal contribution

134
Q

Partial mole (karyotype and parental contribution)

A

Triploid, usually with an extra paternal chromosome set

135
Q

Two individuals in a family who have the same allele or alleles at a locus because they inherited the alleles from a common ancestor

A

Identity by descent

136
Q

The phenomenon of different expression of alleles depending on the parent of origin

A

Imprinting (ex: Angelman syndrome, Prader-Willi syndrome)

137
Q

A genetically determined biochemical disorder in which a specific protein defect produces a metabolic block that may have pathological consequences

A

Inborn error of metabolism

138
Q

The mating of closely related individuals

A

Inbreeding

139
Q

A trait that is inherited in a dominant manner, but is more severe in a homozygote than in a heterozygote

A

Incompletely dominant

140
Q

The family member affected with a genetic disorder who is the first to draw attention to a pedigree

A

Index case or Proband

141
Q

A deletion that does not destroy the normal reading frame of the gene

A

In-frame deletion

142
Q

A chromosomal abnormality in which a DNA segment from one chromosome is inserted into another chromosome

A

Insertion

143
Q

The ability of cells from patients with similar phenotypes, due to mutations in different genes, to correct one another

A

Intergenic complementation

144
Q

A segment of a gene that is initially transcribed but then removed from within the primary RNA transcript by splicing together the sequences on either side of it

A

Intron

145
Q

A chromosomal rearrangement in which a segment of a chromosome is reversed end to end

A

Inversion

146
Q

Pericentric Inversion

A

Centromere is included in the inversion

147
Q

Paracentric Inversion

A

Centromere is not included in the inversion

148
Q

A reproductive technology in which sperm are allowed to fertilize an egg in tissue culture and the fertilized eggs are then introduced back into the uterus to allow implantation

A

In vitro fertilization

149
Q

An abnormal chromosome in which one arm is duplicated

A

Isochromosome

150
Q

The chromosome constitution of an individual; or the photomicrograph of the chromosomes of an individual systematically arranged

A

Karyotype

151
Q

A unit of 1000 bases in a DNA or RNA sequence

A

kilobase (kb)

152
Q

A statistical method in which the genotypes and phenotypes of parents and offspring in families are studied to determine whether two or more loci are assorting independently or exhibiting linkage during meiosis

A

Linkage analysis

153
Q

Genes on the same chromosome which are transmitted together in meiosis more frequently than chance would allow

A

Linkage

154
Q

The occurrence of specific combination of alleles in coupling phase at two or more linked loci more frequently than expected by chance from the frequency of the alleles in the population; proof is determined by a LOD score of 3 (1000:1 odds)

A

Linkage disequilibrium

155
Q

The position occupied by a gene on a chromosome

A

Locus

156
Q

The production of identical phenotypes by mutations at two or more different loci

A

Locus heterogeneity

157
Q

A mutation associated with a reduction or a complete loss of one or more of th enormal functions of a protein

A

Loss-of-function mutation

158
Q

Loss of a normal allele from a region of one chromosome of a pair, allowing a defective allele on the homologous chromosome to be clinically manifest

A

Loss of heterozygosity (LOH)

159
Q

Original term used for the phenomenon of X-inactivation

A

Lyonization

160
Q

The complex locus on chromosome 6p that includes the highly polymorphic human leukocyte antigen (HLA) genes

A

Major histocompatibility complex (MHC)

161
Q

Behavior that harms others

A

Maleficence

162
Q

A pattern of inheritance of a trait from a father to all of his sons and none of his daughters

A

Male-to-male transmission, or Holandric inheritance

163
Q

A recognizable pattern of dysmorphic features having a single cause, either genetic or environmental

A

Malformation syndrome

164
Q

A female heterozygous for an X-linked disorder in whom the trait is expressed clinically, typically due to nonrandom X inactivation

A

Manifesting heterozygote

165
Q

The transmission of genetic information only through the mother

A

Maternal inheritance

166
Q

Laboratory test that relies on measurement of the levels of particular substances, such as AFP, hCG, and uE3 in a pregnant woman’s blood, to screen for fetuses affected with certain trisomies or with neural tube defects

A

Maternal serum screening

167
Q

A unit of 1,000,000 bases or base pairs in genomic DNA

A

megabase (Mb)

168
Q

The type of cell division occurring in the germ cells, by which gametes containing the haploid chromosome number are produced from diploid cells

A

Meiosis

169
Q

When does reduction in chromosome number take place>

A

Meiosis I

170
Q

Patterns of inheritance that follow the classic laws of Mendel: autosomal dominant and recessive, and X-linked

A

Mendelian

171
Q

A type of chromosome with a central centromere and arms of apparently equal length

A

Metacentric

172
Q

Spread of malignant cells to other sites in the body

A

Metastasis

173
Q

A chromosomal deletion that is too small to be seen under the microscope

A

Microdeletion

174
Q

A mutation that changes a codon specific for one amino acid to specify another amino acid

A

Missense mutation

175
Q

A step in oogenesis in which only a small sample of the total number of mitochondria is passed on to daughter cells, allowing significant variation in the proportions of mutant and wild-type mitochondria inherited by the daughter cells

A

Mitochondrial bottleneck

176
Q

DNA with is only maternally inherited

A

Mitochondrial DNA

177
Q

The inheritance of a trait encoded in the mitochondrial genome

A

Mitochondrial inheritance

178
Q

The process of ordinary cell division, resulting in the formation of two cells genetically identical to the parent cell

A

Mitosis

179
Q

A gene that alters the phenotype associated with mutations in a nonallelic gene

A

Modifier gene

180
Q

A chromosome constitution in which one member of a chromosome pair is missing

A

Monosomy

181
Q

Twins derived from a single zygote and thus genetically identical

A

Monozygotic twins

182
Q

An individual or tissue with at least two cell lines differing in genotype or karyotype, derived from a single zygote

A

Mosaic

183
Q

A pedigree in which there is more than one case of a particular disorder

A

Multiplex

184
Q

A laboratory method that allows many different tests to be performed simultaneously on the same sample

A

Multiplex testing

185
Q

An agent that increases the spontaneous mutation rate by causing changes in DNA

A

Mutagen

186
Q

Any permanent heritable change in the sequence of genomic DNA

A

Mutation

187
Q

The frequency of mutation at a given locus, expressed as mutation per locus per gamete (or per generation)

A

Mutation rate (mu)

188
Q

The extent to which testing negative indicates that one does not have or will not develop the disease

A

Negative predictive value

189
Q

An abnormal growth produced by imbalance between normal cellular proliferation and normal cellular attrition; may be benign or malignant

A

Neoplasia

190
Q

The failure of tow members of a chromosome pair to disjoin during meiosis II or mitosis, so that both pass to one daughter cell and the other daughter cell receives neither

A

Nondisjunction

191
Q

A single-base substitution in DNA resulting in a chain-termination (or stop) codon, preventing further synthesis of the polypeptide chain

A

Nonsense mutation

192
Q

A technique used for detection of RNA molecules by hybridization to a complementary DNA probe

A

Northern blotting

193
Q

An US finding of an echo-free space between the skin line and the soft tissue overlying the cervical spine in the subcutaneous tissue of the fetal neck; if increase, may be associated with fetal aneuploidy

A

Nuchal translucency

194
Q

An allele that results in either the total absence of the gene product or in the total loss of function of the product

A

Null allele

195
Q

An individual who may be clinically unaffected but on the basis of pedigree analysis must carry a specific mutant allele

A

Obligate heterozygote or carrier

196
Q

A dominantly acting gene responsible for tumor development

A

Oncogene

197
Q

The developmental history of an organism

A

Ontogeny

198
Q

The short arm of a chromosome

A

p-arm

199
Q

A phenomenon seen with the inheritance of unstable repeat expansion mutations in which expansion of the repeat occur preferentially when the mutation is transmitted by one parent versus the other

A

Parental transmission bias

200
Q

A family history of a hereditary condition, or a diagram of a family history

A

Pedigree

201
Q

The fraction of individuals with a genotype known to cause a disease who have nay signs or symptoms of the disease

A

Penetrance

202
Q

The effects of a drug or its metabolites on physiological function and metabolic pathways

A

Pharmacodynamics

203
Q

The area of biochemical genetics concerned with the impact of genetic variation on drub response and metabolism

A

Pharmacogenetics

204
Q

The application of genomic information or methods to pharmocogenetic problems

A

Pharmacogenomics

205
Q

The rate at which the body absorbs, transports, metabolizes, or excretes a drub or its metabolites

A

Pharmacokinetics

206
Q

A mimic of a phenotype that is usually determined by a specific genotype, produced instead by the interaction of some environmental factor with a normal genotype

A

Phenocopy

207
Q

The observed biochemical, physiological, and morphological characteristics of an individual, as determined by his or her genotype and the environment in which it is expressed; the abnormalities resulting from a particular mutant gene

A

Phenotype

208
Q

The structurally abnormal chromosome 22 that typically occurs in a proportion of the bone marrow cells in most patients with CML; a reciprocal translocation between the distal portion of 22q and the distal portion of 9q

A

Philadelphia chromosome (Ph)

209
Q

Multiple phenotypic effects of a single allele or pair of alleles; effects may not be obviously related

A

Pleiotropy

210
Q

An embryonic cell that is capable of giving rise to different types of differentiated tissues or structures, depending on its location and environmental influences

A

Pluripotent

211
Q

A single nucleotide base pair change in DNA

A

Point mutation

212
Q

Inheritance determined by many genes at different loci, with small additive effects

A

Polygenic

213
Q

The molecular genetic technique by which a short DNA or RNA sequence is amplified enormously by means of two flanking oligonucleotide primers used in repeated cycles of primer extension and DNA synthesis with DNA polymerase

A

Polymerase chain reaction (PCR)

214
Q

The occurrence together in a population of two or more alternative genotypes, each at a frequency greater than which could be maintained by recurrent mutation alone

A

Polymorphism

215
Q

Any multiple of the basic haploid chromosome number other than the diploid number (3n, 4n, etc)

A

Polyploid

216
Q

The extent to which testing positive indicates that one has or will develop the disease

A

Positive predictive value

217
Q

A type of prenatal diagnosis in which a cell is removed from a multi-cell embryo generated by IVF and tested for the presence of a disease-causing mutation

A

Preimplantation diagnosis (PGD)

218
Q

In unstable repeat disorders, a moderate expansion of the number of repeats that is at increased risk of undergoing further expansion during meiosis and causing the full disorder in the offspring; can be asymptomatic

A

Premutation

219
Q

A normal gene involved in some aspect of cell division or proliferation that may become activated by mutation or other mechanism to become an oncogene

A

Proto-oncogene

220
Q

Segment of the X and Y chromosome, located at the most distal portion of their respective p and q arms, at which crossing over occurs during male meiosis; traits will appear to be inherited as autosomal traits

A

Pseudoautosomal region

221
Q

A clinically benign allele that has a reduction in functional activity detected by in vitro assays but that has sufficient activity in vivo to prevent haploinsufficiency

A

Pseudodeficiency allele

222
Q

An inactive gene within a gene family, derived by mutation of an ancestral active gene and frequently located within the same region of the chromosome as its functional counterpart

A

Pseudogene

223
Q

The occurrence of a single cytogenetically abnormal cell in a cytogenetic analysis of a CVS or amnio specimen; generally considered artifactual and of no clinical significance

A

Pseudomosaicism

224
Q

The long arm of a chromsome

A

q arm

225
Q

The frequency of the less common allele of a pair

A

q (from Hardy-Weinberg)

226
Q

The frequency of the more common allele of a pair

A

p (from Hardy-Weinberg)

227
Q

A trait than an individual either has or does not have

A

Qualitative trait

228
Q

A measurable quantity that differs among different individuals, often following a normal distribution in the population

A

Quantitative trait

229
Q

Selection of a mate without regard to the genotype of the mate

A

Random mating

230
Q

Chromosome breakage followed by reconstitution in an abnormal combination, can be balanced or unbalanced

A

Rearrangement

231
Q

A trait that is expressed only in homozygotes, compound heterozygotes, or hemizygotes

A

Recessive

232
Q

An individual who has a new combination of alleles not found in either parent

A

Recombinant

233
Q

A chromosome that results from exchange of reciprocal segments by crossing over between a homologous pair of parental chromosomes during meiosis

A

Recombinant Chromosome

234
Q

The formation of new combinations of alleles in coupling by crossing over between their loci

A

Recombination

235
Q

The probability that a genetic disorder present in one or more members of a family will recur in another member of the same or a subsequent generation

A

Recurrence risk

236
Q

A gene that codes for an RNA or protein molecule that regulates the expression of other genes

A

Regulatory gene

237
Q

A comparison of the risk for a disease or trait in individuals who share a particular factor (such as genotype, environmental exposure, or a drug) versus the risk among individuals who lack the factor.

A

Relative risk

238
Q

Random distribution of mitochondria into daughter cells

A

Replicative segregation

239
Q

An enzyme, derived from bacteria, that can recognize a specific sequence of DNA and cleave the DNA molecule within the recognition site or at some nearby site

A

Restriction enzyme (endonuclease)

240
Q

A polymorphic difference in DNA sequence between individuals that can be recognized by restriction enzymes

A

RFPL (restriction fragment length polymorphism)

241
Q

A short sequence in DNA that can be recognized and cut by a specific restriction enzyme

A

Restriction site

242
Q

A structurally abnormal chromosome in which the telomere of each chromosome arm has been deleted and the broken arms have reunited in ring formation

A

Ring chromosome

243
Q

The probability of an event’s occurring, varying from 0 to 1

A

Risk

244
Q

A nucleic acid formed on a DNA template, containing ribose instead of deoxyribose

A

RNA

245
Q

An enzyme that synthesizes RNA on a DNA template

A

RNA polymerase

246
Q

A translocation between two acrocentric chromosomes by fusion at or near the centromere, with loss of the short arms

A

Robertsonian translocation

247
Q

The method widely used to determine the nucleotide sequence of a DNA molecule (not WES).

A

Sanger sequencing

248
Q

DNA containing many tandem repeats of a short basic repeating unit

A

Satellite DNA (not the same as chromosomal satellite)

249
Q

Loss of a small segment from one chromosome of a pair, resulting in hemizygosity for genes in that segment on the homologous chromosome

A

Segmental aneusomy

250
Q

The disjunction of homologous chromosomes at meiosis

A

Segregation

251
Q

A statistical method that assesses the phenotypes of individuals in families to determine the most likely mode of inheritance of a disease or trait

A

Segregation analysis

252
Q

The frequency with which the test result is positive when the disorder is present

A

Sensitivity (TP/(TP+FP))

253
Q

A recognizable pattern of dysmorphic features due to a number of different causes

A

Sequence

254
Q

A trait that is not X-linked in its pattern of inheritance, but is expressed differently, either in degree or in frequency, in males and in females

A

Sex-influenced trait

255
Q

A trait that is expressed in only one sex, although the gene that determines the trait is not X-linked

A

Sex-limited trait

256
Q

A DNA sequence that acts in cis to decrease transcription of a nearby gene

A

Silencer

257
Q

A mutant gene that has no detectable phenotypic effect

A

Silent allele

258
Q

A disorder due to one or a pair of mutant alleles at a single locus

A

Single-gene disorder

259
Q

A polymorphism in DNA sequence consisting of variation in a single base

A

(SNP) Single nucleotide polymorphism

260
Q

A mutation occurring in a somatic cell rather than in the germline

A

Somatic mutation

261
Q

A technique for preparation of a filter to which DNA has been transferred, following restriction enzyme digestion and gel electrophoresis to separate the DNA molecules by size

A

Southern blotting

262
Q

The frequency with which a test result is negative when the disease is absent

A

Specificity (TN/(TN+FN))

263
Q

A disease that is not the result of inheritance of a disease-causing allele from a parent, often the result of a new germline or somatic mutation

A

Sporadic

264
Q

A type of cell capable both of self-renewal and of proliferation and differentiation

A

Stem cell

265
Q

A gene coding for any RNA or protein product

A

Structural gene

266
Q

A protein that serves a structural role in the body, such as collagen

A

Structural protein

267
Q

A type of chromosome with arms of different lengths

A

Submetacentric

268
Q

A characteristic pattern of anomalies, presumed to be causally related

A

Syndrome

269
Q

A birth defect of the hands and feet characterized by extra digits and the fusion of adjoining digits

A

Synpolydactyly

270
Q

The physical presence together on the same chromosome of two or more gene loci, whether or not they are close enough together for linkage to be demonstrated

A

Synteny

271
Q

Two or more copies of the same or similar DNA sequence arranged in a direct succession along a chromosome

A

Tandem repeats

272
Q

A cell with three copies of each chromosome, or an individual made up of such cells

A

Triploid

273
Q

The state of having three representatives of a given chromosome instead of the usual pair

A

Trisomy

274
Q

A normal gene involved in the regulation of cell proliferation, in which recessive mutations can lead to tumor development

A

Tumor-suppressor gene

275
Q

The hypothesis that some forms of cancer can be initiated when both alleles of a tumor-suppressor gene become inactivated in the same cell

A

Two-hit hypothesis/model

276
Q

A technique in which high frequency sound waves are used to examine internal body structures, useful in prenatal diagnosis

A

Ultrasonography

277
Q

The presence in the karyotype of two copies of a specific chromosome, both inherited from one parent, with no representative of that chromosome from the other parent

A

Uniparental disomy

278
Q

In UPD, if both homologues of the parental pair are present

A

Heterodisomy

279
Q

In UPD, if one parental homologue is present in duplicate

A

Isodisomy

280
Q

Diseases that occur when a gene contains tandemly repeating units of a few nucleotides and the number of such units increases beyond a threshold and interferes with the expression or function of that gene.

A

Unstable repeat expansion disorders

281
Q

A technique used for the detection of proteins, usually by immunological methods

A

Western blotting

282
Q

A term used to indicate the normal allele, or the normal phenotype

A

Wild-type

283
Q

Reciprocal translocation between an X chromosome and an autosome

A

X;autosome translocation

284
Q

Inactivation of genes on one X chromosome in comatic cells of female mammals, occurring early in embryonic life

A

X inactivation

285
Q

The distinctive inheritance pattern of alleles at loci on the X chromosome that do not undergo recombination during male meiosis

A

X linkage

286
Q

Genes on the Y chromsome, or traits determined by such genes, are Y linked

A

Y linkage

287
Q

The number of zygotes from which a multiple birth is derived

A

Zygosity

288
Q

A fertilized ovum

A

Zygote

289
Q

One of three codons (UAG, UAA, and UGA) that terminate synthesis of a polypeptide

A

Stop codon (termination codon)