Genetic conditions

Question 1

How many genetic conditions are estimated to exist?

Answer 1

4000-6000

Question 2

What is defined as a ‘rare disease’ in the UK?

Answer 2

one that affects 1 in 2,000 or less of the population

Question 3

How many people in the UK will be affected by a rare disease at some point in their life?

Answer 3

1 in 17 (3 million)

Question 4

What percentage of newly diagnosed cases of rare diseases are in children?

Answer 4

50%

Question 5

How many different rare diseases exist?

Answer 5

5000-8000

Question 6

What percentage of rare diseases have a known genetic origin?

Answer 6

80%

Question 7

What is genetic counselling?

Answer 7

a role that is developing alongside those within genetics

supports patients and families in understanding their health and the impact genetics may have on treatment options

Question 8

What is CRISPR-Cas9?

Answer 8

a genome editing tool that allows the removal and replacement of certain DNA
used in personalised medicine to advance patient care and even cure inherited diseases

Question 9

What does CRISPR stand for?

Answer 9

clustered regularly interspaced short palindromic repeats

Question 10

What are the two components of CRISPR?

Answer 10

Cas9 protein - cuts DNA

guide RNA - recognises the DNA sequence to be edited

Question 11

What are the stages involved in the use of CRISPR-Cas9?

Answer 11

(1) scientists identify the sequence of the human genome that causes a health problem
(2) scientists create a specific guide RNA (gRNA) to recognise the DNA sequence
(3) gRNA is attached to Cas9 and the complex is introduced to the target cells
(4) it locates the target letter sequence and cuts the DNA
(5) at this point, scientists can edit the existing genome by modifying/deleting/inserting new sequences

Question 12

What are the two types of mutations?

Answer 12

germline - occur in sperm and egg cells and inherited from the mother or father
somatic - occur in any other cell type and not inherited

Question 13

When mutated, which genes are involved in the development of breast cancer?

Answer 13

BRCA1 (chromosome 17) and BRCA2 (chromosome 13)

usually inherited

Question 14

What does BRCA stand for?

Answer 14

breast cancer suppressor gene

Question 15

Besides breast cancer, BRCA mutations are linked to an increased risk of which other cancers?

Answer 15

ovarian, pancreatic, prostate

Question 16

Who should be made aware of and undergo genetic testing?

Answer 16

strong family history of cancer

a relative with a known BRCA mutation

Question 17

Why is it important to know your BRCA-mutation status?

Answer 17

patient can make an informed decision and proactively address cancer risk and the risk to family members as well as any future treatment decisions

Question 18

What are the two types of test to detect a BRCA mutation?

Answer 18

(1) blood/saliva - to examine the presence of germline mutations
(2) tumour testing - breast biopsy to examine the presence of germline and somatic mutations (unidentifiable in a blood/saliva test)

Question 19

What factors need to be considered before a patient undergoes genetic testing?

Answer 19

risks and benefits (many implications of knowing genetic status)

Question 20

How many genes have been identified as being potentially involved in the development of multiple sclerosis?

Answer 20

over 200

Question 21

Why is MS not passed directly from parents to children?

Answer 21

it is not caused by a single gene

Question 22

What is the chance of a person developing MS if they have one parent with MS?

Answer 22

1 in 67

Question 23

What is the chance of a person developing MS if they have a sibling with MS?

Answer 23

1 in 37

Question 24

What is the chance of a person developing MS if they have an identical twin with MS?

Answer 24

1 in 5

Question 25

What proportion of the population have inherited familial hypercholesterolaemia (FH)?

Answer 25

1 in 250

Question 26

What causes FH?

Answer 26

the sufferer inherits a gene mutation in the LDL receptor from one parent

Question 27

What is homozygous FH?

Answer 27

the sufferer inherits the gene mutation from both parents | more severe form of FH

Question 28

What factors could suggest a diagnosis of FH?

Answer 28

total cholesterol level >7.5 mmol/L (should have fasting blood test to measure LDL cholesterol) family history of heart attack under the age of 60

Question 29

What lifestyle factors can help to reduce cholesterol levels?

Answer 29

heart healthy diet regular exercise maintain a healthy weight avoid smoking

Question 30

Why are statins the first-line treatment for most patients with FH?

Answer 30

safe and effective | slow down cholesterol production

Question 31

What treatment is available for patients who do not respond to the best available medication?

Answer 31

injectable therapies

Question 32

What treatment is available for patients with homozygous FH?

Answer 32

medication to slow down LDL production

Question 33

How many genetic mutations have researchers found to occur commonly in patients with rheumatoid arthritis (RA)?

Answer 33

over 100

Question 34

Which two genes are particularly associated with RA?

Answer 34

HLA-DRB1 gene and protein tyrosine phosphatase 22 (PTPN22) gene

Question 35

What is the HLA-DRB1 gene?

Answer 35

the strongest known genetic risk factor for RA there are many different variants of this gene and several are associated with an increased risk of RA some evidence of an interaction between certain variants of the gene and environmental factors the risk of developing RA is increased in smokers and who also have certain high risk HLA-DRB1 variants

Question 36

What is the PTPN22 gene?

Answer 36

unclear exactly how this gene predisposes to autoimmune disease known to be associated with an increased risk of developing RA

Question 37

What is the prevalence of cystic fibrosis (CF) in the UK?

Answer 37

10,500

Question 38

What proportion of people carry the gene for CF with no symptoms?

Answer 38

1 in 25

Question 39

What is the chance of being born with CF if both your parents carry the gene?

Answer 39

1 in 4

Question 40

What causes CF?

Answer 40

a faulty gene that disrupts the movement of salt and water in cells this makes mucus thicker and stickier sticky mucus affects lungs and digestive system airways become clogged up with mucus causing infection and damage over time

Question 41

What are some of the main symptoms of CF?

Answer 41

``` frequent chest infections severe coughs shortness of breath abnormal bowel movements difficulty gaining weight infertility (for most men) ```

Question 42

Why should people with CF never meet each other?

Answer 42

infections that are transmitted between people with CF cause illness

Question 43

What is the treatment for CF?

Answer 43

medication (sometimes more than 40 tablets per day) - to thin mucus antibiotics - to kill bacterial infections in the lungs enzyme capsules - to take with food high-fat diet - to ensure the body receives sufficient nutrients physiotherapy - to move the mucus that builds up around the organs lung transplant - if conventional treatments are no longer effective

Question 44

What causes Crohn's disease?

Answer 44

a combination of genetic, environmental, and lifestyle factors, many of which are unknown many genes related to the disease, including NOD2, ATG16L1, IL23R, and IRGM, are located on chromosomes 5 and 10, which are involved in immunity not inherited but appears to run in some families (present in more than one relative in 15% of cases)