Genetics

Question 1

What are mutations?

Answer 1

Alterations of bases in the code

Question 2

What is the result of a mutation?

Answer 2

Protein is malformed

Question 3

Phenotype

Answer 3

When acharacteristic coded for is physically presented

Question 4

Genotype

Answer 4

The genetic code of a person

Question 5

Aneuploidy:

Answer 5

More/fewer chromosomes that normal

Question 6

Deletion:

Answer 6

Part of chromosome or DNA code is missing

Question 7

Inversion:

Answer 7

A piece of chromosome breaks and turns around and then reattaches

Question 8

Ring

Answer 8

The ends of a chromosome attach to each other, forming a ring

Question 9

Translocation:

Answer 9

Segment of a chromosome separates and reattaches to another site on the chromosome or on a different chromosome entirely

Question 10

Mosaicism:

Answer 10

2 or more sets of chromosomes in the cell with different genetic material
If some cells are affected, it will lead to a milder version of the condition

Question 11

What is the group name for downs, edwards and pataus?

Answer 11

Trisomy

Question 12

What chromosome is affected in Down’s syndrome?

Answer 12

21

Question 13

What chromosome is affected in edwards syndrome?

Answer 13

18

Question 14

What chromosome is affected in pataus syndrome?

Answer 14

13

Question 15

Options of screening for trisomy conditions:

Answer 15

• none
• downs only
• e&p only
  -all three

Question 16

What is the Trisomy screening and when does it happen?

Answer 16

-between 11-14 weeks
- blood test and scan
- scan for the nuchal fold
- blood test measures levels of Papp-A and hCG

Question 17

What measurement of the nuchal fold, Papp-A and hCG correlates to a trisomy condition?

Answer 17

-high nuchal fold measurements
-low Papp-A
-High hCG

Question 18

What does the quadruple screening test for?

Answer 18

• Down’s syndrome only
  -blood test between 14-20 weeks
• tests for alpha-fetoprotien (AFP), hCG, estriol and inhibit A

Question 19

What’s classed as a high/low result for trisomy?

Answer 19

High= 1 in 150 or less

Low= 1 in 151 or more

Question 20

What is NIPT:

Answer 20

-Non-invasive prenatal testing
-follow on screening test when previous screening is high result
-takes maternal blood and screens for fetal DNA

Question 21

Order of most reliable screening to least:

Answer 21

1) NIPT
2) Combined
3)Quadruple

Question 22

What is sickle cell disease:

Answer 22

• autosomal recessive
• RBC are sickle shaped
  -clump together causing inflammation
  -RBC have a lower o2 carrying capacity
  -mainly affects Afro-Caribbean ethnicities

Question 23

What is thalassaemia:

Answer 23

-autosomal recessive
-RBC produce little/no haemoglobin
- anaemia
-affects south Asian, Middle Eastern ethnicities

Question 24

Screening for thalassaemia:

Answer 24

• offered to all pregnant women
• blood tests
  -If pregnant woman is a carrier than partner is screened
• if both are carriers than diagnostic testing is offered

Question 25

Screening for sickle cell disease:

Answer 25

• offered to women who live in areas of high prevalence
  -family origin questionnaire may determine whether one needs screening
  -if pregnant women is a carrier, partner is screened
• if both are carriers, diagnostic testing is offered

Question 26

What is chronic villus sampling:

Answer 26

-diagnostic testing
-needle inserted via abdomen/cervix to obtain sample of placental tissue to obtain fetal DNA
-between 11-14 weeks
- risk of miscarriage is 0.5%

Question 27

What is Amniocentesis:

Answer 27

-fine needle is inserted to obtain a sample of amniotic fluid
-fetal DNA is obtained and screened
- between 15-20 weeks
Risk of miscarriage is 0.5%

Question 28

What is a neural tube defect?

Answer 28

-Spinal cord doesn’t fuse
-caused by genetic and environmental factors
-screened for at the anomaly scan