numerical & structural abnormalities (3)

Question 1

give me 2 examples of events that can cause triploidy

Answer 1

1. failure in gametogenesis of one of the meiotic divisions

2. during dispermy (fertilization of a haploid egg by two sperm)

Question 2

what is the definition of aneuploidy?

Answer 2

Gain or loss of chromosomes equaling less than 1 complete complement
o Usually not inherited but due to meiotic or mitotic nondisjunction errors

Question 3

explain to me the 3 parts of a nomenclauture chromosome shiz

Answer 3

1. The total number of chromosomes
2. The sex chromosome complement
3. Any chromosome abnormalities

Question 4

what chromosome is the problem in patau syndrome?

Answer 4

chromosome 13

Question 5

what are some symptoms assocaited with patau syndrome

Answer 5

much more severe than downs, FTT, “rocker bottom feet”, heart defect
bilateral cleft lip & palate
punched out scalp- missing hair on top of scalp
polydactyly-multiple digits on hands/feet

Question 6

what chromosome is the problem in edward’s syndrome?

Answer 6

chromosome 18

Question 7

holla at me some symptoms of edward’s syndrome

Answer 7

Severe muscle hypertonia, low birth weight, VSD, rocker bottom feet
Will not develop the normal milestones of children. Usually don’t talk, walk or potty train. Receding chin
Sloping head
“hand sign” thumb over palm, fingers down and pinky over the fingers

Question 8

whats the nomenclature of klinefelter syndrome?

Answer 8

47, XXY

Question 9

what are some symptoms of klinefelter syndrome

Answer 9

tall stature, infertility (prob due to hyalinized testicular tubules, small testicles and azoospermia), some female characteristics may develop (extra fat on hips, breast can develop), learning deficit possible

Question 10

what are some symptoms of a XYY male?

Answer 10

• Tall stature

* Normal intelligence, normal fertility, clinically indistinguishable from 46, XY

Question 11

what are the symptoms of XXX females

Answer 11

• Average tall stature, some can have learning issues, some can have fertility problems (but this is uncommon)

Question 12

what is usually the cause of XXX females?

Answer 12

Usually due to maternal meiosis I error

Question 13

what is usually the cause of klinefelter patients?

Answer 13

50% due to meiosis I error father

Question 14

what is the nomenclature for turner syndrome?

Answer 14

45, X

Question 15

what are some symptoms of turner’s syndrome?

Answer 15

Short, short fingers, neck webbing (due to edema around the neck causing the skin to stretch around the neck which doesn’t return after birth “cystic hygroma”)
Gonadal dysgenesis, primary amenorrhea, usually infertile except for the patients with a X/XX mosaicism

Question 16

are XY females infertile?

Answer 16

yeah :(

due to lack of any functional internal genitalia

Question 17

what can result if a pregnant women has CAH

Answer 17

androgens can cross the placenta, so a normal female fetus may develop ambiguous genitalia due to exposure from excess hormones from a CAH affected mother

Question 18

define mosaicism

Answer 18

presence of at least 2 diff cell lines with at least 1 clear variation between them

Question 19

is mosaicism acquire or inherited? why?

Answer 19

ONLY can be acquired

this is because you need 2 cells. And a zygote is only 1 cell. So cannot be there

Question 20

what is a chimera?

Answer 20

2 separate cell lines that eventually fused to form 1 organism

Question 21

what is a terminal deletion? how many breaks does it require?

Answer 21

deletion that occurs at distal end of 1 arm of a chromosome. This requires only 1 break

Question 22

what is a intersitial deletion? how many breaks does it require?

Answer 22

internal region of the chromosome is loss. Requires 2 breaks

Question 23

what chromosome is deleted in wolf hirschlorn syndrome?

Answer 23

short arm of chromosome 4

Question 24

list some symptoms of wolf hirschlorn syndrome

Answer 24

Microcephaly, micrognathia, hypotonia, epicanthal folds, “starled or surprised expression”, arched brows, long nose with squared off end, short stature, developmental delay (usually end up in special ed)

Question 25

what is the result of a duplication?

Answer 25

partial trisomy

Question 26

describe terminal duplications

Answer 26

are usually a direct duplication of the material adjacent to it

Question 27

describe intersitial duplications

Answer 27

have extra DNA within a chromosome- usually a copy of adjacent regions

Question 28

are duplications usually sporadic or inherited?

Answer 28

sporadic but could be inherited from parent with benign chromosome rearrangment

Question 29

if a patient has a balanced translocation and is clinically normal, what can be assumed about their children with the same balanced translocation?

Answer 29

that the children will also be clinically normal

Question 30

define robertosonian translcations

Answer 30

centromere to centromere translocation involving acrocentric chromosome

Question 31

which arms fuse in roberstonian translocations? what arms are lost?

Answer 31

long arms fuse, net loss of both short arms

Question 32

how many chromosomes does roberstonian translocation patients usually have? are they clinically normal?

Answer 32

usually clinically normal but have 45 chromosomes (because 2 of the chromosomes are fused together)

Question 33

what is more common in robertosian translocations: homologous chromosomes or nonhomologus

Answer 33

nonhomologous but can occur in homologous as well

Question 34

what are the two fertility problems that can result from a parent with robertosonian homologous translocation

Answer 34

1. A cell with a robertsonian translocation (two copies of 21) which if fertilized will give rise to a down syndrome child
2. Or a cell with no copies of chromosome 21 which if fertilized will result in monosomy 21 which is not compatible with life

Question 35

how many breaks are required in a chromosome for an inversion to occur?

Answer 35

at least 2

Question 36

what type of inversion does the following describe:
“two breaks occur on the same side of the centromere (in the same arm) such that the centromere is not involved in the rearrangement”

Answer 36

paracentric inversion

Question 37

what type of inversion does the following describe:
“breaks occur on opposite sides of the centromere and the segment reverses order generating a new chromosome with the same genes in a diff order:”

Answer 37

pericentric inversion

Question 38

for a paracentric inversion, for the chromosomes to pair properly and produce proper gametes, do you want recombination to occur or not occur in the inversion loop

Answer 38

not occur

Question 39

what two types of chromosomes will occur if there has been recombination in the inversion loop?

Answer 39

1. dicentric chromosome- with two centromeres

2. acentric chromosome- no chromosomes

Question 40

for pericentric inversion, is there an inversion loop?

Answer 40

yes

Question 41

for pericentric inversion, what is more viable, large inversions or small inversions?

Answer 41

large inversions