Genetic Material

Question 1

How common is chromosomal conditions in miscarriages

Answer 1

50%

Question 2

Aneuploidy

Answer 2

More or fewer chromosomes than normal

Question 3

Deletion

Answer 3

Whe part of chromosome is missing or part of dna code is missing

Question 4

Inversion

Answer 4

A chromosome breaks and the piece of it turns around and reattaches itself

Question 5

What is a ring chromosome

Answer 5

Where the ends are attached to itself to form a ring

Question 6

Translocation

Answer 6

A chromosome segment rearranges from one location to another. It can happen either with in he same chromosome or move to another chromosome

Question 7

Mosaicism

Answer 7

2 or more sets of chromosome in the cells with different genetic material

Question 8

What is trisomy

Answer 8

Presence of extra chromosome

Question 9

How does trisomy occur

Answer 9

Asa result of non disjunction - the paired chromosomes fail to move to opposite poles during meiosis so do not divide evenly
This leaves 1 chromosome in one cell and three in the other cel rather than. 2 and 2
Alll are fatal in utero apart from. Trisomy of chromosome 21 (downs),18 (Edward’s) and 13 (Patau)

Question 10

What are the screening choices

Answer 10

No screening
Only downs
Only Edward’s and pataus
Downs edwards and pataus

Question 11

What is combined screening for trisomy conditions

Answer 11

Ultrasound and blood test

Question 12

When does combined screening happen

Answer 12

Between 11-14 week

Question 13

What does the ultrasound do in combined screening

Answer 13

Measures the fluid on he back of the fetal neck - nucal translucency

Question 14

What is measured in the blood test for screening test

Answer 14

PAPP-A and hCG levels

Question 15

What is correlated with a foetus with trisomy condition

Answer 15

High measurement of nuchal fold
Low measurement of PAPP-A
High levels of hCG
Results from the tests are collated with maternal age to give individualism chance for foetus having downs

Question 16

What is a high risk of downs

Answer 16

1;150 or less

Question 17

What is low risk of downs

Answer 17

1:151 or more

Question 18

Quadruple screening for downs

Answer 18

Blood test only takes place betweeen 14-20 weeks
Tests for alpha- fetal protein (AFP), human chlorionic gonadrotropin (hCG), estriol and inhibin A.- four markers
Less accurate than combined test - 5% false positive

Question 19

What is the NIPT

Answer 19

Non invasive prenatal testing is a folllow up screening test for a high chance result from imbibed or quadruple test
Takes sample of maternal blood and screens piece of DNA some of which are fetal from the placenta.it screens for more than expected levels of DNA from chromosomes 13,18 and 21
42 per 100,000 results will be a false productive

Question 20

Whe are autosomal dominant conditions screened an why

Answer 20

Under specific circumstances - family history
More likely to be known bout by the family so special screening can be offered

Question 21

Whe are autosomal recessive conditions screened and why

Answer 21

Offered routinely to pregnant women
Occurs less frequently in the family pedigree

Question 22

What is sickle cell diease

Answer 22

Red blood cells are sickle shaped rather than biconcave
They dump together abusing them to get stuck in small blood vessels
Can cause inflammatory diseases
Causes anaemia severe pain and life threatening infections.
Mainly affects people of Friday or Caribbean origin

Question 23

What is thalassaemia

Answer 23

Red blood cells produce no or little amounts of haemoglobin
It causes severe anaemia requiring frequent blood transfusion and medications

Question 24

Who does thalasseamia affect most

Answer 24

Mainly affects people of Mediterranean, south Asian southeast Asian and Middle Eastern origin

Question 25

How is screening for sickle cell and thalasseamia performed

Answer 25

Thalasseamia offfered to all Screening for SCD offered to all who live in area of hig prevalence where greater then 1.5 per 10000 pregnancies affected by this condition Blood test is performed before 10 weeks If pregnant women is found to be a carrier the biological father of the unborn baby will be offered screening too If both are carries the women will be offered diagnostic testing to see if the feus is affected by the condition

Question 26

How do you diagnostically test for fetal genetic conditions

Answer 26

Chorionic villus sampling Amniocentesis PCR Microarray Karyotyping

Question 27

Chlorionic villus sampling

Answer 27

Local anaesthetic used to numb the abdomen Fine edge inserted intro abdominal to obtain a sample of placental tissue to test fetal dna Ultrasound scan is used to guide the needle Performed between 11-14 weeks but can be done later Risk of miscarriage approx 0.5% following procedure

Question 28

Amniocentesis

Answer 28

Local anaesthetic used to numb abdomen Fine needle inserted and sample of amniotic fluid is O’Brien’s Ultrasound scan is used to guide the needle Fetal dna in the amniotic fluid is tested for genetic conditions Performed between 15 - 20 weeks but can be done later

Question 29

PCR

Answer 29

Heat and enzymes - polymerase - used to multiply, deconstructed then reconstruct dna so equipment can detect genetic variations Results ina few days Targets specific genetic changes

Question 30

Microarray

Answer 30

Lab tool used to detect the expression of thousands of genes at the same time DNA microarrays are microscopic slides that are inter with thousands of tiny spot in defined positions with each spot contain a known dna sequence or gene Sample compared with a reference sample o detect genetic differences

Question 31

Karyotyping

Answer 31

Pairing and ordering all the chromosome providing a genome - wide snapshot of an individuals chromosome Staining used to reveal the structural feature on. Glass slide under a microscope

Question 32

What s neural tube defects

Answer 32

The neural tube develops to form the spinal ord, brain and spine With a defect the spinal cord does not fs instead it remains open Multi factorial condition cause by multiple genetic and multiple environment factors. Sub clinic a genetic mutation is exposed to aggravating conditions - including folate deficiency, maternal diabetes, anti-convulsant mdcation, smoking an obesity Varies in severity from spinal bifilar - affects exposure of spinal cord - -to anencephaly - affects exposure/ absence of brain Neural tube defects are primarily screened for at the 18-20 week anomaly ultrasound scan

Question 33

Who is involved in clinical genetics

Answer 33

Collaboration between Family Clinical genetics sevice Cytogenetic laboratories molecular Genetics laboratories Other medical departments Lay support groups

Question 34

What do clinical genetics do

Answer 34

Diagnose/confirm a genetic condition Assess referred patients and relatives level of risk of a genetic condition Provide required info Provide psychological support Make recommendations Make referrals

Question 35

What are the aim of geneti counselling

Answer 35

Help the individuals and families to. Understand he medical facts Appreciate the way heredity contributes to the disorder and reoccur acne Understand the options for dealing itch recurrence Choose the course of action hichseems appropriate them Make the best possible adjustment to the disorder

Question 36

What are the core principles of genetic counselling

Answer 36

Autonmy of individual Patients right. Full and complete information ina Orem they understand Preservation of confidentiality Aimed at. Facultative decision making with time to explore all options

Question 37

What at the referra; pathways for clinical genetics

Answer 37

Patient contacts clinical genetics directly - self referral Via g, midwife Secondary care practioners Clinical laboratories

Question 38

Who is offered a referral for genetic counselling

Answer 38

People who suspect they have genetic condition People itch family history of genetic condition Pregnancy people with genetic issues People with a sting family family history of cancer Infants and children suspected of having a genetic conditioon

Question 39

Role of midwife

Answer 39

Simplify terms Gain consent Provide support Reassurance Non judgmental, No bias Educate and inform