General (1)

Question 1

What step of the cell cycle is the most error-prone?

Answer 1

anaphase I

chromosomes separate at centromere

Question 2

At what phase do oocytes pause from formation until ovulation?

Answer 2

prophase I

Question 3

Where is the polyA tail located?

Answer 3

the 3’ UTR

Question 4

What is the TATA box?

Answer 4

a promoter sequence upstream of the transcription start site

Question 5

What is the CAT box?

Answer 5

a region upstream of the TATA box ; important for transcription, normal gene expression

Question 6

What is the start codon?

Answer 6

AUG

methionine

Question 7

What are the 3 stop codons?

Answer 7

UAA, UGA, UAG

Question 8

How many kb are in the mitochondrial genome?

How many genes?

Answer 8

16kb

37 genes

Question 9

What is the difference between a proband and a consultand?

Answer 9

proband: first affected person who brings an issue to attention
consultand: first person who seeks genetic counseling

Question 10

What does “sex-limited” mean?

Answer 10

a defect is inherited in an autosomal fashion, but affects only one sex
ex: HBOC

Question 11

What is a missense mutation?

Answer 11

a mutation leading to a different amino acid

Question 12

What is a nonsense mutation?

Answer 12

a single base substitution leading to a premature stop codon; yields a shortened and usually nonfunctional protein

Question 13

What is an example of a dinucleotide mutation hotspot?

Answer 13

CG

methylated Cs can spontaneously deaminate to form T

Question 14

What percentage of sperm contain a new deleterious mutation?

Answer 14

10%

Question 15

What are tested in a paternity test?

Answer 15

microsatellites

Question 16

What is a linkage analysis?

Answer 16

a determination of the distance between 2 genes based on frequency with which they remain together through meiosis

Question 17

What is the most common chromosome rearrangement?

Answer 17

13q14q Robertsonian translocation

Question 18

What is the incidence of chromosome abnormalities in newborns?

Answer 18

0.7%

1/160

Question 19

What is the incidence of chromosome abnormalities in miscarriages?

Answer 19

40-50%

20% of them are 45,X

Question 20

What is a complete mole?

Answer 20

paternal chromosomes only

no fetus, abnormal placenta

Question 21

What is a partial mole?

Answer 21

triploid (2/3 of cases have 2 paternal sets and 1 maternal set of chromosomes)
atrophic fetus, remnants of a placenta

Question 22

What syndrome is the most common cause of mental retardation?

Answer 22

Down syndrome, T21

Question 23

How many genes are on the Y chromosome?

Answer 23

50

Question 24

At what point in embryonic development are the gonads bipotential? What happens then?

Answer 24

6th week

if TDF is present it acts as switch to stop ovarian development

Question 25

What percentage of genes are inactivated during X-inactivation?

Answer 25

85% - 90%

Question 26

What is the function of hemoglobin?

Answer 26

to carry oxygen in red blood cells

Question 27

In what regions of a gene does nonsense mediated decay occur?

Answer 27

when the nonsense mutations are more than 50bp 5’ to the end

Question 28

What is allelic heterogeneity?

Answer 28

when there can be multiple mutations (leading to multiple alleles) at a specific locus which lead to the same phenotype

Question 29

What is locus heterogeneity?

Answer 29

when there are multiple loci associated with the same disease

Question 30

What is the most common indication for prenatal diagnosis?

Answer 30

advanced maternal age

Question 31

If an amniocentesis is performed too early, what risks are present?

Answer 31

miscarriage, club feet

Question 32

What percentage of neural tube defects occur with a positive family history?

Answer 32

5%

Question 33

How long do fetal lymphocytes remain present in maternal blood?

Answer 33

years - may confound fetal cell sampling in future pregnancies

Question 34

If a neural tube defect occurs in a pregnancy, what is the risk that it will happen in a subsequent pregnancy between that couple?

Answer 34

4%

Question 35

What are the criteria for effective newborn screening programs? (6)

Answer 35

1) treatment is available
2) starting treatment early can reduce or eliminate severity of disease
3) there is no other way (exam) to notice the disorder in a newborn
4) rapid and economical testing is available with high sensitivity (no false negatives) and somewhat specific (few false positives)
5) condition is relatively common such that the screening is worth the cost
6) societal infrastructure is in place to inform parents/doctors and begin treatment

Question 36

What are the 3 cardinal principles of medical ethics?

Answer 36

• beneficence
• respect for individual autonomy
• justice

Question 37

What teratogenic substance can lead to heart defects?

Answer 37

lithium

Question 38

What 3 congenital phenotypes have a 30% syndromic, 70% nonsyndromic breakdown?

Answer 38

• hearing loss
• heart defects
• cleft lip

Question 39

What 4 congenital phenotypes have a prevalence of approx. 1/1000?

Answer 39

• hearing loss
• NTDs
• clefting
• congenital heart defects

Question 40

What are 5 phenotypes which should make you consider chromosome abnormalities?

Answer 40

• global DD, MR
• major malformations
• multiple minor anomalies
• growth retardation
• hearing loss

Question 41

Other than a neurologist, what two types of specialists are especially important for patients with neuromuscular disorders?

Answer 41

• cardiologist

- respiratory therapist

Question 42

What is the carrier frequency of CF in caucasians, blacks, asians?

Answer 42

caucasian: 1/28
black: 1/61
asian: 1/87

Question 43

What is the most common molecular cause of overgrowth?

Answer 43

hypomethylation

Question 44

What is another term for anomaly?

Answer 44

malformation