Genetic Counselling Flashcards
What is genetic counselling?
A communication process which deals with human problems associated with the occurrence, or the risk of occurrence, of a genetic disorder in a family’.
What is the role of a genetic counseller?
Comprehend the medical facts, including the diagnosis
Understand the way in which heredity contributes to the disorder, and the risk of recurrence in relatives
Explore the alternatives for dealing with the risk of recurrence
Choose the course of action which seems to them appropriate
Make the best possible adjustment to the disorder in an affected family member and/or the risk of recurrence of that disorder
What information needs to be gathered at a consultation?
Medical and social history
Family history, ages at diagnosis etc
Confirmations of diagnoses, genetic test reports
What information is given at a consultation?
The condition
Inheritance patterns
Occurrence/Recurrence risks
What options are offered at a consultation?
Whether or not to have a genetic test (diagnostic/predictive/carrier/prenatal)
Screening and preventative options
Reproductive options
Issues to be aware of in a consultation?
- Loss and Grief
- Guilt and Blame
- Family myths and beliefs
- Culture and religious beliefs
- Confidentiality and informed consent
- Distress – can be a sign that someone is not adjusting to a situation
Grief and loss around childhood and adolescence?
Birth of a child with disabilities, loss of the perceived child
Loss of an infant e.g. Tay Sachs
Loss of young adult e.g. CF, FAP
Illness of a parent e.g. HD, cancer
When would genetic testing be offered?
Genetic testing following confirmation that they have inherited a faulty gene or notice symptoms e.g. Huntington’s
Grief and loss surrounding genetic testing results?
Loss of a ‘part’ - genetic testing may lead a person to confront surgery i.e. mastectomy or colectomy e.g. BRCA1 gene or FAP gene
Survivor guilt when they get a good predictive result
Issues with family dynamics?
Old wounds and concealed hatreds may be expressed
Difficulty in re-contacting an estranged branch of the family
Refusal to give consent for medical information
Reluctance to tell other family members a diagnosis
What is transcultural genetic counselling?
Transcultural genetic counselling is not about being an expert on any given culture, rather it is a way of thinking about patients that acknowledges and values culture:
- Belief and disbelief about science, invasive testing, postmortem
- Pressures to have children
- Communication in correct language
- Beware of making assumptions e.g. that termination of pregnancy would not be acceptable
When testing children for adult-onset conditions, what questions should be asked?
- Can it wait until older?
- Will it cause insurance problems?
- Are there treatments or any benefits to knowing?
- Will their autonomy be respected?
- Do they know enough to understand what is happening?
- Are the parents making the decision without the child’s involvement?
What is amniocentesis?
Amniocentesis is a procedure in which amniotic fluid is removed from the uterus for testing or treatment. This fluid contains foetal cells and various proteins.
What does amniocentesis test for?
Foetal abnormalities (birth defects) such as Down syndrome, cystic fibrosis or spina bifida.
Who is amniocentesis offered to?
Only offered to pregnant women who have a higher chance of having a baby with a genetic or chromosomal condition
What is chorionic villus sampling?
A small sample of cells (called chorionic villi) is taken from the placenta where it attaches to the wall of the uterus
What does CVS test for?
To check if your baby has a genetic or chromosomal condition, such as Down’s syndrome, Edwards’ syndrome or Patau’s syndrome.
Who is CVS offered to?
Only offered to pregnant women with an increased risk of having a baby with a genetic or chromosomal condition
What is PGD?
Pre-implantation genetic diagnosis.
A treatment which involves checking the genes or chromosomes of your embryos for a specific genetic condition.
Why is PGD complex?
Because the embryos need to be tested in a lab, you will need to have IVF.
Embryos which have been tested and are free of the condition will be placed back into your womb to hopefully continue to develop
Who is offered PGD?
you have ended previous pregnancies because of a serious genetic condition
you already have a child with a serious genetic condition and want to avoid this happening again
you have a family history of a serious genetic condition, or
you have a family history of chromosome problems.
What conditions does PGD test for?
PGD can be used to test for almost any genetic condition where a specific gene is known to cause that condition.
Risks of amniocentesis / CVS?
Slight risk of miscarriage (larger in CVS)
Also have to face tough decision - termination?
Diagnostic challenge for childhood congenital deafness?
50% genetic cause
50% other causes (prematurity, infection during pregnancy, childhood infection)
Of the 50% of congenital childhood deafness, how many are syndromic? How many are nonsyndromic?
Syndromic - 30%
Nonsyndromic - 70%
What is syndromic hearing loss?
syndromic hearing loss occurs with signs and symptoms affecting other parts of the body
What is nonsyndromic hearing loss?
Hearing loss is a partial or total loss of hearing that is not associated with other signs and symptoms.
Of the nonsyndromic cases of hearing loss, what types of inheritance are they caused by?
- 75-85% recessive genes
- 10-15% dominant genes
- 5-15% X-linked genes or mitochondrial inheritance
What is usher syndrome?
Primarily characterised by deafness accompanied by retinitis pigmentosa
What is FAP?
Familial adenomatous polyposis (FAP) is a dominantly inherited predisposition to the development of many hundreds to thousands of adenomatous polyps of the colon.
What is the mean age of onset of FAP? How would this affect genetic testing?
The mean age of onset is around 15 years, symptoms may arise in the third decade, and the median age for the development of colonic cancer is 35–40 years.
Reduces age of testing –> testing earlier is better.
The suggested age of testing is around 12.
What is exclusion testing?
Exclusion testing means that the at-risk parent doesn’t have to have a genetic test to have disease-free children.
E.g. Huntington’s:
Exclusion testing involves testing a foetus (unborn baby) around 10-15 weeks into a pregnancy to see if it has the tracking marker for Huntington’s but NOT testing parent
