L8-Cytogenetics

Question 1

What % of conceptions have a chromosomal abnormality?

Answer 1

7.5%!! (0.5% of births tho)

Question 2

Chromosome number other than 46 is called _________. Exact multiple of haploid chromosome number (n) is _______. Any other chromosome number is _________.

Answer 2

HETEROPLOID……EUPLOID…..ANEUPLOID

Question 3

How many chromosomes are in a Triploid? Tetraploid? How does each happen? What is the survival rate?

Answer 3

triploid-69 chromosomes (2 sperm, 1 egg birth but not long term survival)…..tetraploid 92 chromosomes (no cleavage after mitosis of zygote, no births)

Question 4

What are the three major Aneuploidies?

Answer 4

Turner Syndrome (45,X)…Kleinfelter Syndrome (47,XXY)….Trisomy 21-Down Syndrome

Question 5

What are the two main culprits for Down Syndrome? What are the %’s?

Answer 5

Trisomy 21-95%….Robertsonian translocation-4%

Question 6

What % of Down Syndrome occurs from maternal Meiosis I errors? What % from paternal Meiosis II errors?

Answer 6

90% maternal, 10% paternal

Question 7

How many chromosomes are present in robertsonian translocation down syndrome?

Answer 7

46 (mom translocates with 2 afrocentric chromosomes)

Question 8

What is the only viable monosomy in humans?

Answer 8

turner syndrome (45,X-50%)

Question 9

How much does each parent contribute to Kleinfelters?

Answer 9

50/50

Question 10

What is the cause of 47,XXY males?

Answer 10

Paternal nondisjuntion during MII

Question 11

Parent of origin effects: Hydatidifom Moles-who is to blame?

Answer 11

46,XX ALL PATERNAL

Question 12

Parent of Origin effects: Ovarian teratomas-who is to blame?

Answer 12

46,XX- All Maternal

Question 13

How can you have a male calico cat?

Answer 13

XXY!!!

Question 14

To perform high resolution chromosome analysis, should the cells be arrested earlier or later in mitosis compared to a standard karyotype?

Answer 14

EARLIER!