GENETICS Flashcards

1
Q

Detects fetal Down Syndrome and other autosomal trisomies

A

Aneuploidy screening

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2
Q

Clinically useful if the fetus is at risk for an X-linked disorder

A

Fetal sex determination

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3
Q

May also be beneficial if the fetus is at risk for congenital adrenal hyperplasia because maternal corticosteroid therapy may be avoided if the fetus is male

A

Fetal sex determination

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4
Q

Fetal cells are present in maternal blood at a _______ concentration

A

very low

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5
Q

released from apopotic placental triphoblast—rather than actual fetal cells—and can be reliably detected in maternal blood after 7 weeks’ gestation

A

Cell free fetal DNA

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6
Q

If a specific disease causing gene has not been identified, then _________ may be used to estimate the likelihood that an individual or fetus has inherited the abnormal trait

A

linkage analysis

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7
Q

Uses the principles of PCR (polymerase chain reaction) and nucleic acid hybridization to screen DNA

A

Chromosomal Microarray Analysis

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8
Q

For prenatal diagnosis for stillbirth evaluation

A

Chromosomal Microarray analysis

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9
Q

allows identification of one or several DNA fragments of interest

A

Southern blotting

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10
Q

Enables the rapid synthesis of large amounts of a specific DNA sequence or gene

A

PCR

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11
Q

For any tissue containing dividing cells or cells that can be stimulated to divide

A

Cytogenic analysis

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12
Q

Provides a rapid method for determining numerical changes of selected chromosomes and confirming the presence or absence of a specific gene or DNA sequence

A

Flourescence In Situ Hybridization (FISH)

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13
Q

A recessive trait is expressed only when both copies of the gene function in the same way

A

Autosomal Recessive Inheritance

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14
Q

When considering inheritance, it is the ________ that is dominant or recessive, not the genotype function in the same way

A

phenotype

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15
Q

A __________ is caused by a mutation or alteration in a single locus or gene in one or both members of a gene pair

A

monogenic disorder

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16
Q

Mechanism may be either mitotic nondisjunction or parental correction of a meiotic error

A

Confined placental mosaicism

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17
Q

Likely arises from a mitotic error in cells destined to become the gonad and results in population of abnormal germ cells

A

Gonadal mosaicism

18
Q

A mosaic individual has two or more cytogenetically distinct cell lines that are derived from a single zygote

A

Chromosomal mosaicism

19
Q

Results when deletions occur at both ends of the same chromosome and the ends come together

A

Ring chromosomes

20
Q

Breaks in both p and q arms

A

Pericentric inversion

21
Q

Two breaks within one arm

A

Paracentric inversion

22
Q

These abnormal chromosomes are composed of either two q arms or two p arms of one chromosome fused together

A

Isochromosomes

23
Q

Can arise when the centromere breaks transversely instead of longitudinally during meiosis II or mitosis

A

Isochromosomes

24
Q

Can also result from a meiotic error in a chromosome with a robertsonian translocation

A

Isochromosomes

25
Involves only acrocentric chromosomes which are chromosomes 13,14,15,21 and 22
Robertsonian translocation
26
The q arms of two acrocentric chromosomes fuse at one centromere to form a derivative chromosome
Robertsonian translocation
27
Develops when there are breaks in two different chromosomes and the broken fragments are exchanged, so that each affected chromosome contains a fragment of the other
Reciprocal translocation
28
DNA arrangements in which a segment of DNA breaks away from one chromosome and attaches to another
Chromosomal Translocations
29
The arranged chromosomes are called _________
derivative chromosomes
30
2 types of derivative chromosomes are:
Reciprocal Robertsonian
31
Examples of Microduplication syndrome:
1. Velocardiofacial/DiGeorge 2. Smith-Magenis 3. Williams-Beuren
32
Microdeletion syndrome are also known as:
DiGeorge Syndrome Sphrintzen syndrome Velocardiofacial syndrome
33
45,X
Turner Syndrome (Monosomy X)
34
47,XXY
Klinefelter Syndrome
35
A lethal aneuploidy, more than 90% of fetuses with either a dandric or digynic form have multiple structural anomalies (CNS, heart, face and extremities, severe growth restriction)
Triploidy
36
Extra chromosomal set is maternal, and the egg fails to undergo the first or second meiotic division before fertilization
Digynic triploidy (type II triploidy)
37
Extra chromosomal set is paternal resulting from fertilization of one egg by two sperm or by a single diploid
Diandic triploidy (type I triploidy)
38
Account for approximately 20% of spontaneous abortions
Polyploidy
39
Abnormal number of complete haploid chromosomal sets
Polyploidy
40
_________ is the most common trisomy found in the first-trimester losses
Trisomy 16