Week 1 - Genetics

Question 1

Give some examples of conditions that are autosomal dominant inheritance.

Answer 1

NF1, Achondroplasia, hypercholesterolaemia

Question 2

Give some examples of Autosomal Recessive inherits conditions.

Answer 2

Cystic Fibrosis, sickle cell anaemia, PKU

Question 3

Give examples of X-linked recessive inherited conditions.

Answer 3

Duchenne muscular dystrophy, Fragile X

Question 4

Give examples of X-linked dominant inherited conditions.

Answer 4

Retts syndrome, Vitamin-D resistent rickets, incontinentia pigmenti

Question 5

What are some conditions with genetic anticipation?

Answer 5

Huntington disease, fragile X syndrome, Myotonic dystrophy, spinocerebellar ataxia

Question 6

What is an example of pseudo-dominant inheritance?

Answer 6

Gilberts syndrome

Question 7

What is the difference between normal DNA and mitochondrial?

Answer 7

Normal: linear, double helix, in chromosomes, millions of genes, contains exons and introns.
Mitochondrial: Circular, smaller genome, 37 genes, no introns, 66% of genome coding DNA

Question 8

What genetic condition is caused by a mutation in the base excision repair gene?

Answer 8

MYP polyposis (AR)
(milder form of familial adenomatous polyposis - APC mutation, (AD))

Question 9

What mutation causes Li fraumeni syndrome and what can it predispose to?

Answer 9

TP53 AD

Brain tumours, breast cancer, sarcoma, leukaemia, adrenal cortical carcinoma.

Question 10

Give some characteristics of Edwards syndrome (trisomy 18)

Answer 10

Small chin, Malformation of heart, kidneys and other organs, clenched fists with overlapping fingers, cleft lip and palate, microphthalmia, abnormal ears

Question 11

Give some characteristics of Patau syndrome

Answer 11

Congenital heart disease, 50% die within a month, 10% survive first year, generally with profound learning difficulties, cleft lip and palate, microphthalmia

Question 12

What are some characteristics of Huntington disease (AD with genetic anticipation)

Answer 12

Age onset 30-50
Progressive chorea ,Dementia, Psychiatric problems, Problems swallowing and with co-ordination, lower weight
CAG repeat in coding region

Question 13

What characteristics might you see in Myotonic dystrophy (AD with genetic anticipation)

Answer 13

Progressive muscle weakness adult onset
myotonia, cataracts
CTG repeats in translated but untranscribed (downstream region) of DMPK gene. Abnormal DMPK mRNA - indirect toxic effects on splicing

Question 14

CF is AR with CFTR mutation at e.g. F508del. what are some features?

Answer 14

Recurrent lung infection, exocrine pancreatic insufficiency - (increased thickness of secretions)
Test via immunoreactive trypsin level and sweat testing

Question 15

What is neurofibromatosis type 1

Answer 15

AD - NF is a tumour of the myelin sheath
Diagnosis: 
> 6 café au lait patches
Minimum of 2 skin neurofibromas 
2 or more iris litchi nodules

Question 16

What is the mutation in Duchenne muscular dystrophy

Answer 16

DMD gene Xp21

Question 17

What areas might mitochondrial syndromes affect?

Answer 17

Muscle, brain, eyes

Question 18

Allele specific (ARMS) PCR is a form of detecting point mutations, how does it work?

Answer 18

Detects a singe nucleotide substitution in a known position in a gene

Question 19

What chromosomes are BRCA 1 and 2 on? (BRCA- repair ds breaks)

Answer 19

1 - 17

2- 13

Question 20

What do TSG usually do? Loss of function

Answer 20

Inhibits the progression through the cell cycle.
Promote apoptosis
Act as stability genes
(MLH1, MSH2, APC)

Question 21

What do promo-oncogenes do? Gain of function

Answer 21

Stimulate the cell cycle (MYC gene), the normal response to GF

Question 22

What is the difference between the TSG and porto-oncogene?

Answer 22

P-O - only requires 1 allele to be mutated

TSG - both alleles must be mutated - Knudsen’s 2 hit hypothesis

Question 23

What is cancer predisposition syndrome?

Answer 23

Genetic mutation that increases the chances of developing cancer at an earlier age compared to risk for general population. usually inherited AD mostly due to mutated TSG

Question 24

In what inheritance pattern is consanguinity important?

Answer 24

AR

Question 25

What inheritance pattern shows knights move?

Answer 25

X-linked Recessive

Question 26

What is cascade screening?

Answer 26

Lab test that identifies people at risk of a genetic condition by systemic family tracing

Question 27

Give some examples of cancer predisposition syndromes.

Answer 27

Hereditary non-polyposis colon cancer
Familial adenomatous polyposis 
Li framenti syndrome 
MUTYH polyposis 
Fanconi anaemia