diseases from single gene mutations

ALO 1: Explain the operation of multiple alleles in the ABO blood system.
ALO 2: Link retinitis pigmentosa to a marker locus on chromosome 7.
ALO 3: Discuss genetics in medicine, including DNA fingerprinting and gene therapy.
ALO 4: Understand genetic testing, counselling, prenatal diagnosis, genetic screening, and the role of genetic counsellors.
ALO 5: Discuss human genetics, its societal implications, and ethical considerations regarding genetics.

Blood Transfusion: Clumping of donated red cells occurs if recipient's serum has matching antibodies.
Genes Affecting Blood Types:
- Alleles IA and IB synthesize agglutinogens A and B (dominant).
- Genotype combinations lead to blood groups:
  - Group A: IAIA or IAi
  - Group B: IBIB or IBi
  - Group AB: IAIB
  - Group O: ii
Parental Blood Groups and Possible Outcomes:
- Example pairings include:
  - O x O = O (1)
  - O x A = A, O (2)
  - O x B = B, O (2)
  - A x B = A, B, AB, O (4)
Genetic blood types are stable over a person's life and can help predict offspring blood groups, serving as a tool in parentage disputes.

Description: Hereditary disorder affecting photoreceptors, leading to night blindness and constricted visual field.
Symptoms: Night blindness, optical disc pallor, narrowed arterioles.
Genetic Inheritance: Inherited primarily with two gene copies needed; however, one copy can sometimes cause the condition.
- it creates a waxy optic disc pallor
Genetic Basis: Linked to mutations in over 60 genes, leading to nonsyndromic retinitis pigmentosa.
Treatment Options: Currently, there is no cure, but management strategies include the use of visual aids and potential gene therapy approaches under investigation.
- linked on chromosome 7 marker

Unique DNA: Every individual, barring identical twins, has unique DNA.
Genetic Variation: Approximately 1 in 500 base pairs differ between humans, with some variations tied to diseases:
- Cystic fibrosis
- Cardiovascular diseases

Certain DNA differences can signify inherited diseases—these markers facilitate predictive testing and genetic counselling.

Method: Analyzes repeating DNA sequences known as VNTRs (Variable Number of Tandem Repeats).
Types of Repeats:
- Microsatellites (shorter than 10 bp)
- Minisatellites (10-100 bp)
Applications: Used in forensic science, including sexual assault cases through DNA analysis of samples.
DNA Fingerprinting: digested by enzyme to produce fragements containing VNTRs
- amplifed by PCR
- analyzed by electrophoreis to produce bands

Concept: Involves correcting defective genes to treat diseases, such as replacing 'bad' genes with a 'good' gene.
Delivery Methods:
- Viral vectors (adenoviruses, retroviruses, etc.)
- Non-viral methods (liposomes, polymers, etc.)
Gene therapy has shown promise for diseases like cancer, cystic fibrosis, and hemophilia.

Examples of clinical trials include treatments for severe combined immune deficiency and retinitis pigmentosa.

Amniocentesis: A technique to diagnose genetic diseases before birth by sampling amniotic fluid.
Use Case: Recommended for women over 35 due to higher risk of chromosomal abnormalities like Down Syndrome.

Newborn screening: Early detection can prevent serious conditions like sickle cell anemia.
Adult screening: Facilitates informed reproductive choices, such as identifying carriers of recessive disorders.

Responsibilities: Assess risk, interpret test outcomes, and support familial decisions regarding genetic disorders.
Common reasons to consult include pregnancy, family planning, and cancer risk assessment.

Genetic Discrimination: Involves unfair treatment based on genetic factors; highlighted in cases like Angelina Jolie's preventive surgeries following risk assessments.
Mitochondrial Replacement Therapy: Raises ethical questions about the implications of inheriting DNA from a third party.

Understanding genetics is essential for addressing medical, ethical, and social issues surrounding inherited diseases and genetic information.