Chromosomes and their Abnormalities

Question 1

What are 4 ways to a provider deals with genetics with their patient

Answer 1

Obtain family history, Order genetic testing, PRovide genetic counseling, Advise treatment for genetic diseases

Question 2

What are the two main things a physician looks for when ordering genetic testing?

Answer 2

Test for Chromosomal Abnormalities (Karyotyping), Test for genetic defects

Question 3

A patient approaches you and are concerned about their expecting child might have a genetic disease. What are the best ways to help provide counsel for the patient?

Answer 3

Explain the inheritance pattern of the disease, Provide basic information about that disease and the population, Explain the risk factors that influence the outcome of the disease to the patients

Question 4

What are the three main types of genetic diseases?

Answer 4

Chromosomal abnormalities (Least common), Single-gene defects, Multi-factorial genetic disease (Most common)

Question 5

How many chromosomes do Gametes have and what are their shape?

Answer 5

23 chromosomes/cell and are in the haploid shape

Question 6

How many chromosomes do non-sex chromosomes have?

Answer 6

They have ~2500 genes and 46 chromosomes/cell

Question 7

What does the notation 46, XY mean?

Answer 7

The total number of chromosomes and the sex chromosome.

Question 8

What are the significant markers of the three types of chromosomes?

Answer 8

Sub-metacentric have longer Q arms than P arms, Metacentric have equal length Q and P arms, and acrocentric is when the centromere is near one end.

Question 9

In which phase of the cell cycle could could non-disjunction happen?

Answer 9

The M phase

Question 10

When are the sister chromatids formed in the Cell cycle?

Answer 10

During the S1 phase when DNA synthesis is happening

Question 11

What is the definition of non-disjunction?

Answer 11

It is the main cause of incorrect segregation from sister chromatids during mitosis

Question 12

What is it called when one daughter cell ends up with an extra chromosome and the other lacks one?

Answer 12

Mosaicism – cell populations that have different genetic makeups

Question 13

In what types of cells does mosaicism most often occur?

Answer 13

Cancer cells

Question 14

If mosaicism occurs during development of the embryo it can lead to different diseases. what is the most common type of these diseases?

Answer 14

Trisomy 21 which leads to down syndrome

Question 15

What is the role of meiotic crossover?

Answer 15

It increases the genetic diversity in the gamete

Question 16

What happens to the overall chromosome levels in gametes at the end of the meiotic cycle?

Answer 16

Each one only has 23 chromosomes so the total amount is half of when it started.

Question 17

What are the most common outcome of non-disjunction?

Answer 17

spontaneous abortions and serious diseases

Question 18

Which type of disjunction is more sever meiosis or mitosis?

Answer 18

Meiosis

Question 19

What is the definition of uniparental disomy?

Answer 19

When both genes are inherited from the same parent.

Question 20

What does uniparental disomy often lead to?

Answer 20

disorders involving genes under genetic imprinting.

Question 21

What types of diseases are very rarely linked to uniparental disomy?

Answer 21

Autosomal recessive diseases

Question 22

Name the two main types of chromosomal abnormalities.

Answer 22

Abnormal chromosomal count, and structural abnoramlities

Question 23

What are the three main diseases from chromosomal abnormalities?

Answer 23

Intellectual disabilities, developmental problems, and cancer

Question 24

What are the four types of euploids seen?

Answer 24

Haploid and diploid (viable for life), Triploid and tetraploid (not viable for life, lead to early abortions)

Question 25

Explain the two types of aneuploids.

Answer 25

Trisomy and monosomy. Trisomy is when you have three tails of the same chromosome and monosomy is when you only have 1.

Question 26

What 4 chromosomes do you mainly find the trisomy abnormality on?

Answer 26

Chromosomes X, 13, 18, 21

Question 27

Where is the most common monosomy chromosome and what is the disease it is tied into?

Answer 27

Chromosome 45,X and it causes Turner sundrome

Question 28

What is the incidence rate for down syndrome?

Answer 28

1 : 800 child births.

Question 29

What women are at the most risk to have a baby with down syndrome?

Answer 29

Women over the age of 35

Question 30

What are the common signs and symptoms that a child has down syndrome?

Answer 30

Short stature, short neck, flat nasal bridge, open mouth with protruding tongue, Congenital heart disease, and Low IQ.

Question 31

How do you normally write the genetic code from down syndrome?

Answer 31

47, XY (or XX), +21

Question 32

What are the odds of a patient getting down syndrome from a parents through robertsonion translocations?

Answer 32

~4% of down syndrome cases are linked to this.

Question 33

What are three other causes of down syndrome?

Answer 33

21q21q translocation, mosaic down syndrome, partial 21 trisomy

Question 34

Describe trisomy 18 (edwards syndrome)

Answer 34

incidence rate increases as mother ages, intellectual disabilities, failure to thrive, congenital heart problems, 47, XX, +18

Question 35

What are the main S&S from edwards syndrome?

Answer 35

Receding jaw, Low set malformed ear, specifically clenching fist, rocker-bottom feet

Question 36

Explain Trisomy 13 (Patau syndrome)

Answer 36

incidence rate increases as mother ages, intellectual disabilities, failure to thrive, congenital heart problems, 47, XX, +13

Question 37

What are the main S&S from Patau syndrome?

Answer 37

Sloping forehead, cleft-lip, polydactyly (more than 5 fingers), and rocker-bottom feet.

Question 38

Describe Cri Du Chat syndrome.

Answer 38

caused by the deletion of the 5p arm. Cat-like cry, intellectual disabilities, growth retardation, speech impairment, heart problems 46, XX, del(5p)

Question 39

What are the main S&S of Cri Du Chat syndrome

Answer 39

Small head, narrow eyes with greater distance between them, low-set ears, cat-like cry

Question 40

What is so important about the SRY gene?

Answer 40

It is the determining factor of if you are going to be a male or not.

Question 41

Where is the SRY gene located on the Y chromosome?

Answer 41

in the p arm. it can crossover to the X chromosome during development which will lead to infertility.

Question 42

What is the cause of sex reversal?

Answer 42

The transfer of the SRY to the X from the Y that will lead to XX males or XY females.

Question 43

What happens if the SRY gene loses its function?

Answer 43

you get an XY female.

Question 44

What are the three hormones that determine the gonadal development?

Answer 44

DAX1, SOX9, SRY increases SOX 9 expression. If DAX1 is higher it leads to female production. SOX9 leads to male production

Question 45

What happens with a SOX9 gene duplication?

Answer 45

You end up with an XX male

Question 46

What happens with a DAX1 gene duplication?

Answer 46

You end up with an XY female

Question 47

Which region of the gene has the most unsilenced genes?

Answer 47

The distal portion of the p arm in the X chromosome

Question 48

What is the most frequent form of the Klinefelter syndrome?

Answer 48

Males with 47, XXY

Question 49

What are the main S&S of Klinefelter syndrome

Answer 49

Tall feminine like structures, Hypogonadism (infertile), some learning disabilities.

Question 50

Describe Turner Syndrome

Answer 50

Mainly 45,X. They have some learning disabilities, short stature, can’t enter puberty, have streak gonads, and are infertile

Question 51

Main S&S of Turners Syndrome

Answer 51

Webbed neck, Edema in the legs and arms, and a wide man-like chest.

Question 52

What is the one karyotypes of Turners syndrome that can still be fertile?

Answer 52

45,X or 46,XX mosaic