Cytogenetics and Aneuploidy

Question 1

Physicians from ___, ___, ___, ____ and ___ all often refer patients to undergo cytogenetic studies

Answer 1

Neonatal
Reproductive health
Neurology
Endocrinology
Hematology/oncology

Question 2

3 main methods of cytogenetics:

Answer 2

G banded
FISH fluorescence in Situ hybridization
Chromosomal microarrays

Question 3

Only during ____ are chromosomes visible under the light microscope for G banding. You must have ____ cells

Answer 3

Mitosis
Dividing

Question 4

Common cells that can undergo Gbanded studies are:

Answer 4

White blood cells, skin, bone marrow

Question 5

Cells can also be stimulated by ____ to begin dividing

Answer 5

Mitogen

Question 6

Cells are Gbanded in _____ and treat the slide with ___ and ____ stain

Answer 6

Mitosis
Protease
Giemsa

Question 7

Each ____ has a unique G banding pattern that is ____ between individuals

Answer 7

Chromosome
Constant

Question 8

The chromosomes are paired and lined up into a _____

Answer 8

Karyotype

Question 9

When looking at a chromosome under G banding it looks like there is only one, however we are looking at ___ ___

Answer 9

Sister chromatids

Question 10

Writing karyotypes:
Typical ____: 46, XX
variant karyotype: 47, XY, +21

Answer 10

Female

Question 11

____ = the short arm
____ = the long arm

Answer 11

p
q

Question 12

Each G band typically encompasses millions of bass pairs of DNA. For example, 10p13 has _____ base pairs of DNA encompassing ____ genes. Therefore, when there is a visible chromosome abnormality involving loss or gain of 1 or more Gbands, there are ____ clinical issues

Answer 12

5,100,000
40
Multiple

Question 13

The limitations of Gbanding is that you must have a ___ cell and we can visualize only ____ regions

Answer 13

Dividing
Large

Question 14

FISH addresses the limitations of G banding. Don’t need a ___ cell and we can see ____ deletions

Answer 14

Dividing
Smaller

Question 15

FISH:
Obtain DNA from an interest on chromosome which will serve as the ____. Label the DNA with ____ dye. Place cell on a slide and treat with heat to ____ the DNA. The fluorescent dye will find and bond it’s complementary base pairs in the patients DNA. We then ___ the hybridized (binded) fluorescent spots

Answer 15

Probe
Fluorescent
Denature
Count

Question 16

Answer 16

3 copies of 13, instead of 2

Question 17

Limitations of FISH:
Only looking at a ____ region of each chromosome. Can only look at a few ___ per assay.

Answer 17

Small
Probes

Question 18

Trisomy 21 is Down syndrome. 40 to 50% of children with Down syndrome will have a structural ____ defect in the atrioventricular canal. Other Common associates are ____

Answer 18

Heart
Hearing loss
Hypothyroidism
Duodenal atresia
Hypotonia- low muscle tone
Early onset of leukemia

Question 19

______ is abnormal segregation of chromosomes (meiosis I) or sister chromatids (meiosis II, mitosis) and causes trisomy 21. 90% of the time it arises by ____ Nondisjunction error during oogenesis

Answer 19

Nondisjunction
Meiosis I

Question 20

Review

Answer 20

Two homologs should be separating, but both go in to one cell

Question 21

Down syndrome occurs in _____ births. Chance increases as the mother gets older

Answer 21

1/800

Question 22

Trisomy 21 is one of the only _____ trisomies that is compatible with life into adulthood

Answer 22

Autosomal

Question 23

Trisomy 13 and trisomy 18 are the only other trisomies that may be ____.

Answer 23

Live born

Question 24

Trisomy 13 causes ____ with incomplete development of the forebrain. Cleft lip is common. ____ of hands and feet. Severe cognitive disabilities. Cardiac anomalies. Abnormal genitalia

Answer 24

Holoprosencephaly
Polydactyly

Question 25

Answer 25

Question 26

Most autosomal trisomies will result in ____.

Answer 26

Miscarriage

Question 27

Chromosome abnormalities account for approximately ___% of miscarriages. Trisomy 16 has strong association with advanced maternal age and most commonly causes miscarriages

Answer 27

50

Question 28

____ of ___ is a chromosome study performed on tissue from the miscarriage, from the placenta.

Answer 28

Products of conception

Question 29

Sometimes an autosomal trisomy can be seen in a live born if it is in ____ state with a non trisomic cell line

Answer 29

Mosaic

Question 30

_____ is when two or more populations of cells are identified, each has a different karyotype. Usually associated with a ____ severe phenotype but cannot tell what the different distribution of cell lines is in different tissues

Answer 30

Mosaicism
Less

Question 31

Chromosome 21 is one of 5 pairs of chromosomes known as _____ chromosomes (13,14,15,21,22) meaning they have short p arms composed of repetitive DNA sequence coding for _____ RNA

Answer 31

Acrocentric
Ribosomal

Question 32

____ ____ are the most common type of translocation in humans. They involve the joining of two acrocentric chromosomes and there centromeres. In this process, the ____ ____ are lost. Fortunately the lost of the repetitive short arm will not be clinically significant

Answer 32

Robertsonian translocation
Short arms

Question 33

_____ robertsonian translocation is when there is still enough information there it is just rearranged. we don’t have extra of a chromosome or complete loss of a chromosome

Answer 33

Balanced

Question 34

Answer 34

C and D

Question 35

The chromosome 21 and 14 are hooked together in a robertsonian translocation. There are 6 different ways it can segregate:

3 of the 6 gamete’s lead to miscarriage, the one that is viable and not normal is trisomy 21

Answer 35

Question 36

______ robertsonian translocation does cause clinical significant. A physician the must study _____ chromosomes to make sure one of the parents is not carrying the robertsonian translocation in an in ____ form

Answer 36

Unbalanced
Parental
Balanced

Question 37

____ of balanced robertsonian translocations lead to increased probability for pregnancy with trisomy 21

Answer 37

Carriers

Question 38

The mechanisms giving rise to trisomy 21:

Answer 38

Question 39

Extra copy of a sex chromosome do not lead to as severe ____ as trisomies of autosomes

Answer 39

Phenotypes

Question 40

Most sex chromosome aneuploidy do not result in a visible _____. May cause developmental delays or behavior problems. Rarely are these karyotypes brought to medical attention

Answer 40

Abnormalities

Question 41

One common feature of XXX, XXY, and XYY is tall stature due to _____ gene being located on the end of the short arm of both X and Y

Answer 41

SHOX

Question 42

XXY causes _____ syndrome and usually does get brought to medical attention. Causes infertility, small testes, decreases testosterone, enlarged breast, delayed or incomplete puberty

Answer 42

Klinefelter

Question 43

Monosomy X is loss of a sex chromosome, causing ____ syndrome (45X). Results in short stature, primary _____, web neck, scoliosis, edema, cardiac abnormalities, hypothyroidism, renal abnormalities. No ____ disability

Answer 43

Turner
Amenorrhea: reproduction problems
Cognitive

Question 44

____ is very common in Turned Syndrome. Have to do more studies and look at the karyotype to determine the variability in cells

Answer 44

Mosaicism

Question 45

Answer 45

Practice