Multifactorial disease

Question 1

What does polygenic mean?

Answer 1

the result of the action of multiple genes

Question 2

What is familial clustering (Lamda S)

Answer 2

the relative risk to a person in a family where another sibling has the condition by comparison to the risk of the population

Question 3

What are SNPs?

Answer 3

Single nucleotide polymorphisms - change in the letter code at one point

Question 4

Alzheimer disease

Answer 4

most common form of dementia
familial clustering is lamda s 3 to 10
much of the effect is due to a gene implicated in heart disease: app-lipoprotein E (APOE)

Question 5

Which disease is associated with apo-lipoprotein E?

Answer 5

Alzheimer’s disease

Question 6

Which Apo-lipoprotein E haplotype increases susceptibility of alzheimers?

Answer 6

ApoE 4 increases susceptibility

Question 7

Which ApoE haplotype has a protective effect of alzheimers?

Answer 7

ApoE2

Question 8

Age-related macular degeneration

Answer 8

characterised by the early deposition of drusen, a risk factor for AMD
leading to cause of irreversible central vision dysfunction caused by degeneration of the macula

Question 9

What disease is characterised by the early deposition of drusen?

Answer 9

Age-related macular degeneration

Question 10

what are the genetic causes of age-related macular degeneration?

Answer 10

CFH, ARMS2

Question 11

Environment effects of Age related macular degeneration

Answer 11

smoking

light exposure

Question 12

what does penetrance mean?

Answer 12

proportion of individuals with a specific genotype who manifest that phenotype

Question 13

What are gatekeepers?

Answer 13

gatekeepers directly regulate tumour growth, they monitor and control cell division and death, preventing accumulation of mutations

Question 14

what are caretakers?

Answer 14

They improve genomic stability and repair mutations

Question 15

what is the function of tumour suppressor genes?

Answer 15

To protect cells from becoming cancerous

Question 16

What can loss of function of tumour suppressor genes lead to?

Answer 16

cancer

Question 17

What are oncogenes?

Answer 17

Regulate growth and differentiation

gain of function may result in activating mutations and increase the risk of cancer

Question 18

what type of genes obey the two hit hypothesis?

Answer 18

cancer genes

Question 19

Retinoblastoma

Answer 19

childhood ocular cancer
both genes are mutated
inherited cases at younger age
bilateral cases almost always germline

Question 20

Familial adenomatous polyposis

Answer 20

hundreds of bowel polyps from teens onwards
high risk of bowel cancer if untreated
APC tumour suppressor gene affected

Question 21

Hereditary non-polyposis colorectal cancer (NHPCC)

Answer 21

polyps are common but not polyposis
risk of bowel adenoma or cancer
mismatch repair genes

Question 22

which phase in the cell cycle are the chromosomes most visible?

Answer 22

Metaphase

Question 23

Which type of genetic testing are metaphase chromosomes used?

Answer 23

G banding

Question 24

what is diploidy?

Answer 24

2 copies of each chromosome

Question 25

What is aneuploidy?

Answer 25

gain or loss of chromosome, trisomy or monosomy

Question 26

where do chromosome numerical abnormalities originate?

Answer 26

gametogenesis - meiosis increased risk of aneuploidy with increased maternal age fertilisation - polyploidy early cleavage - post zygotic non-disjunction

Question 27

What are the main features of downs syndrome?

Answer 27

``` upward slanting and brush field spots in eyes small nose microcephaly single palmer crease sandal gap protruding tongue short neck males = infertile increased risk of cancer, alzheimers, obesity ```

Question 28

what chromosome is affected in downs syndrome?

Answer 28

trisomy 21

Question 29

What syndrome is trisomy 18

Answer 29

Edwards syndrome

Question 30

what are the main features of Edwards syndrome?

Answer 30

``` microcephaly low set ears rocker bottom feet clenched hands cleft lip and palate severe mental retardation short sternum may umbilical/inguinal hernia, congenital heart disease ```

Question 31

What syndrome is trisomy 13?

Answer 31

Patau syndrome

Question 32

What are the main features of patau syndrome?

Answer 32

``` sloping forehead low set ears, abnormal cleft lip abnormal genital brain defects - holprosencephaly polydactyly and fingers flexed mental retardation ```

Question 33

Turners syndrome 45 X

Answer 33

``` loss of ovarian function, no puberty webbed neck swelling of hands and feet short stature coarctation of aorta ```

Question 34

Klinefelters syndroms 47XXY

Answer 34

``` infertility hypogonadism testicular dysgenesis gynacomastia accelerated growth long limbs ```

Question 35

What is a molar pregnancy?

Answer 35

double paternal chromosomes | no maternal

Question 36

If have double maternal chromosome what are the consequences?

Answer 36

small placenta | small foetus with macrocephaly

Question 37

If have double paternal chromosome what are the consequences?

Answer 37

foetus is normal with facial abnormalities, huge overdeveloped cystic placenta, genome for placenta

Question 38

Which direction are DNA sequences written in?

Answer 38

5 prime to 3 prime direction

Question 39

What is the definition of a gene?

Answer 39

functional unit of DNA components: exons, introns, regulatory sequences

Question 40

What is a pseudogene?

Answer 40

used to be a gene then mutated and became non-functional

Question 41

what is a processed gene?

Answer 41

a copy of a gene which is normal looking but without introns

Question 42

what is satellite DNA?

Answer 42

large blocks of repetitive DNA sequence | large blocks are centromeres and heterochromatic chromosomal regions

Question 43

what is alphoid DNA

Answer 43

a type of DNA found at centromeres 171 bp repeat unit alphoid DNA is required for assembly of the centromere

Question 44

what disease is associated with deficiency of blood coagulation factor 8?

Answer 44

Haemophilia A

Question 45

Haemophilia A mutaiton

Answer 45

x linked recessive | blood coagulation does not work due to deficiency of blood coagulation factor 8