Clincal Cytogenetics Flashcards

(48 cards)

1
Q

Cytogenetics

A

Chromosomal abnormalities that may involve the presence of extra chromosomes, loss of chromosomes, or structural alterations

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2
Q

Dispermy

A

The fertilization of an ovum by two sperm cells

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3
Q

Triploidy

A

Cells that contain three copies of each chromosome 69 total

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4
Q

Robertsonian translocation involves the loss of

A

The short arms of the two Acrocentric chromosomes and the fusion of the long arms at the centromere

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5
Q

Monopolidy

A

The loss of a chromosome set- never seen in humans

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6
Q

Polyploidy

A

The gain of one of more entire chromosome sets

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7
Q

Trisomy 13 is also referred to as

A

Patau syndrome

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8
Q

Nondisjunction can occur in the gametes of

A

Both men and women

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9
Q

What is the most common trisomy among still borns

A

Trisomy 18 Edward Syndrome

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10
Q

Robertsonian translocation only involve ________ chromosomes which are:

A

Acrocentric

13, 14, 15, 21, 22

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11
Q

Down Syndrome characteristics

A
Intellectual disability
Almond eyes
GI tract obstruction
Congenital heart defect
High risk for leukemia
Alzheimer’s-like symptoms later in life
Male sterility 
Hearing loss
Eye abnormalities
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12
Q

Robertsonian translocation is not seen in which trisomy

A

18, Edward syndrome

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13
Q

Instead of 46 XX or 46 XY *normal, a Robertsonian translocation will have

A

45 XX or 45 XY

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14
Q

In a child-bearing female with Robertsonian translocation, the risk of Down Syndrome occurrence is:

A

Much higher than the risk in general population

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15
Q

Small arm of chromosome

A

P

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16
Q

Why are the individuals with Robertsonian translocations phenotypically normal

A

The short arms of the Acrocentric chromosomes contain redundant material (rRNA genes)

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17
Q

Which tirsomy is most compatible with live birth

A

Trisomy 21

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18
Q

Reciprocal translocation:

A

Chromosomal breaks on two chromosomes, the broken chromosomes exchange material resulting in derivative chromosomes

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19
Q

Aneuploidy

A

The gain of one or loss of a single chromosome

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20
Q

Why are abnormalities of the sex chromosomes more tolerated than abnormalities of the autosomes?

A

X-inactivation of most genes on X chromosome

21
Q

An individual who has a sex chromosome abnormality either _______ or ________ gene dosage of ______

A

Increased or decreased gene dosage of PAR1 and PAR2

22
Q

A translocation is the interchange of genetic material between:

A

Non-homologous chromosomes

23
Q

All autosomal monosomies are:

24
Q

Trisomy 18 is also referred to as

A

Edward Syndrome

25
Alternate segregation
Two normal or two abnormal chromes in the gamete (no phenotype)
26
5% of trisomy 13 is a result of
Robertsonian translocation
27
Signs of Turner syndrome
Kidney abnormalities, congenital heart defects, ovarian dysgenesis, hypothyroidism, no intellectual disability but some learning disabilities
28
Klinefelter syndrome:
47 XXY
29
Symptoms of Trisomy 18 Edward syndrome
``` Death within one year Intellectual/developmental disabilities Diaphragmatic hernia/omaphalocele Small eyes/mouth, receding jaw Kidney defects Clenched fists/overlapping fingers Rocker-bottom feet, flexed big toe ```
30
Trisomy 13 Patau syndrome symptoms
``` Death within a year Holoprosencephaly *brain does not make two lobes Postaxial polydactyly Cleft lip/palate Deaf Small eyes ```
31
Why are autosomal trisomies 13, 18, and 21 compatible with life
Fewer genes on these chromosomes
32
Most common sign of Klinefelter syndrome
Infertility
33
Which autosomal trisomies are compatible with survival
13, 18, 21
34
Monosomy for X chromosome is called
Turner syndrome 45, X
35
XX males and XY females are errors during:
Recombination during the generation of gametes, SRY gene translocated
36
Women under/over the age of 35 have 80% of the babies with Down syndrome?
Under
37
Adjacent segregation
One normal and one abnormal chromosomes in the gamete (abnormal phenotype)
38
Treatment for Turner syndrome
Growth hormone and estrogen therapy
39
Why is Robertsonian translocation not possible in trisomy 18
Chromosome 18 is not Acrocentric
40
The only kind of survivable monosomy:
X chromosome
41
Nondisjunction
The failure of the two members of the chromosome pair to disjoin or separate during meiosis 1 or meiosis 2
42
Long arm of chromosome
Q
43
Chromosome abnormalities are the leading cause of:
Pregnancy loss and intellectual disability syndromes
44
In Trisomy 13, 95% of cases are due to
Nondisjunction in the mother’s gametes
45
What are the two types of translocation
Robertsonian | Reciprocal
46
5% of trisomy 21 cases result from
Robertsonian translocation
47
In 95% of trisomy 21 cases, the additional chromosome is contributed by:
The mother due to nondisjunction
48
In males with 46, XX, where was the error
In the father of the individual, there was an aberrant recombination between the X and Y chromosomes that transferred the SRY gene to the X chromosome