8.4.8 Screening Patients

Genetic Screening

Genetic screening is the analysis of DNA to detect specific alleles, mutations, or genetic markers that could indicate genetic conditions, disease risks, or carrier status. This is an important tool in preventative medicine and disease management.

Applications of Genetic Screening

1. Identifying Carriers:

• Detects individuals carrying a recessive allele for genetic disorders like cystic fibrosis or sickle cell anaemia.
• Helps families assess the likelihood of passing on genetic conditions to their children.

2. Pre-implantation Genetic Diagnosis (PGD):

• Used during in vitro fertilisation (IVF) to screen embryos for genetic disorders before implantation.
• Only embryos without genetic conditions are implanted, reducing the risk of inherited diseases.

3. Newborn Screening:

• Performed shortly after birth to detect treatable genetic conditions, such as phenylketonuria (PKU).
• Allows early intervention to prevent severe complications.

4. Predictive Testing:

• Identifies individuals at risk of developing late-onset diseases like Huntington's disease or certain cancers.

5. Personalised Medicine:

• Tailors treatments to an individual's genetic profile, improving the efficacy and safety of therapies.

6. Prenatal Screening:

• Tests foetal DNA obtained via amniocentesis or chorionic villus sampling (CVS) for genetic disorders.

Methods of Genetic Screening

1. DNA Probes and Hybridisation:

• Uses DNA probes to bind to complementary sequences associated with genetic conditions.
• Probes are labelled with radioactive isotopes or fluorescent dyes for detection.

2. Polymerase Chain Reaction (PCR):

• Amplifies specific DNA regions to detect mutations or alleles efficiently.

3. Microarrays:

• A technique that analyses thousands of genes simultaneously to detect variations linked to diseases.

4. Next-Generation Sequencing (NGS):

• Rapidly sequences entire genomes to identify genetic variations comprehensively.

Ethical Considerations

• Privacy: Concerns about who has access to genetic information (e.g., insurers, employers).
• Discrimination: The potential for genetic discrimination based on screening results.
• Psychological Impact: The stress or anxiety associated with learning about genetic risks.
• Consent: Ensuring informed consent for testing, particularly in cases like prenatal screening.