16. Genetics Flashcards
What are the Reasons for Referral to Genetics?
- Family History of Genetic Condition in Relatives
- Diagnosis of Genetic Conditions - Known / Unknown
- Management of Genetic Conditions
- Genetic Counselling - Aiding Decision Making / Increasing Understanding
What do people need to know before undergoing a Genetic Test?
- What the Test is For / What’s the Point in having it done?
- How the Test Works / How likely it is to be Positive
- What happens if it is Positive / Negative
- Chances of False Positive / False Negative
5 Implications for other Family Members of Positive Result
What are the Types of Pregnancy Testing / Screening?
- Targetted
2. Whole Population
When can Genetic Screening occur?
- Antenatal
- Neonatal
- Child
- Adult
- Pre-Pregnancy
- In Maturity
What are the Reproductive Choices for Genetic Testing?
- Nothing - Test at Birth
- Chorionic Villus Sampling
- Amniocentesis
- Pre-Implantation Genetic Diagnosis
- Non-Invasive Prenatal Diagnosis / Testing
- Adoption
- Gamete Donation
What is the Segregation of an X-Linked Recessive Trait (Mother Carrier)?
Normal Father (XY) x Carrier Mother (XXr)
- Normal Daughter - XX
- Normal Son - XY
- Carrier Daughter - XXr
- Affected Son XrY
What is the Segregation of an Autosomal Dominant Trait (One Affected Parent)?
Affected Father (Dd) x Normal Mother (dd):
1. Affected Son - Dd
2. Normal Daughter - dd
3. Affected Daughter Dd
4. Normal Son - dd
Each Child has a 50% chanve of inheriting the mutation
What is the Segregation of an Autosomal Recessive Trait (Both Parents are Carriers)?
Carrier Father (Rr) x Carrier Mother (Rr):
- Normal - RR
- Carrier - Rr
- Carrier - Rr
- Affected - rr
What is the Screening for Down’s Syndrome dependent on?
- Maternal Age
- Triple Screening
- CUBS Screening
- Selection for Amniocentesis
- Free Foetal DNA - Private
What are the Methods of Newborn Screening?
- Clinical Examination
- Hearing
- Blood Spot
What is Screened for in the UK?
- Phenylkentonuria (PKU)
- Congenital Hypothyroidism
- Sickle Cell Disorders
- Medium Chain Acyl-CoA Dehydrogenase Deficiency (MCADD)
- Homocysteinuria
- Isovaleric Acidaemia
- Maple Syrup Urine Disease
- Glutaric Aciduria Type 1
What is the problem in Phenylketonuria?
Baby’s are Unable to break down Phenylalanine (Amino Acid Protein)
If untreated this can lead to the baby developing Serious, Irreversible, Mental Disability
What is the Treatment of Phenylketonuria?
Early with a Strictly Controlled Diet - starts by 21 days of age
What is the problem in Congenital Hypothyroidism?
Not enough Thyroxine
