Model Answer
0 min readIntroduction
Single-gene mutation disorders, also known as Mendelian disorders, arise from alterations in a single gene, deviating from the normal sequence. These mutations are the underlying cause of a significant proportion of inherited diseases, affecting approximately 1 in 200 births globally. Understanding these disorders is crucial for medical anthropology, as they impact human health, genetic diversity, and cultural practices surrounding reproduction and family planning. Recent advancements in genomic sequencing have significantly improved diagnostic capabilities and opened avenues for gene therapies, although ethical considerations remain paramount.
Defining Single-Gene Mutation Disorders
A single-gene mutation disorder results from a change in the DNA sequence of a single gene, which disrupts its normal function. This change can be a substitution, deletion, insertion, or duplication of nucleotides. The inheritance pattern determines how the disorder is passed down through generations.
Classification of Single-Gene Disorders
These disorders can be broadly classified based on their inheritance pattern:
- Autosomal Dominant: Only one copy of the mutated gene is needed for the disorder to manifest. Example: Huntington’s disease, characterized by progressive neurodegeneration.
- Autosomal Recessive: Two copies of the mutated gene are required for the disorder to appear. Carriers (individuals with one copy) are usually unaffected. Example: Cystic Fibrosis, affecting mucus production.
- X-linked Dominant: A single copy of the mutated gene on the X chromosome is sufficient to cause the disorder. Example: Hypophosphatemic rickets.
- X-linked Recessive: Two copies of the mutated gene on the X chromosome are needed for males to be affected; females can be carriers. Example: Hemophilia A, affecting blood clotting.
Molecular Basis and Diagnosis
The molecular basis of these disorders varies depending on the specific mutation. Some mutations lead to the production of a non-functional protein, while others result in altered protein function. Diagnostic techniques include:
- Karyotyping: To identify chromosomal abnormalities.
- DNA Sequencing: To pinpoint the exact mutation in the gene.
- Prenatal Diagnosis: Techniques like amniocentesis and chorionic villus sampling (CVS) can detect mutations during pregnancy.
- Newborn Screening: Some states screen newborns for specific genetic disorders, allowing for early intervention.
Ethical Considerations
Genetic testing and screening for single-gene disorders raise several ethical concerns:
- Genetic Discrimination: Fear of discrimination based on genetic predispositions.
- Privacy Concerns: Protecting the confidentiality of genetic information.
- Reproductive Choices: Ethical dilemmas surrounding prenatal diagnosis and selective abortion.
- Informed Consent: Ensuring individuals fully understand the implications of genetic testing.
| Disorder Type | Inheritance Pattern | Example | Key Feature |
|---|---|---|---|
| Autosomal Dominant | One mutated gene | Huntington's Disease | Progressive neurodegeneration |
| Autosomal Recessive | Two mutated genes | Cystic Fibrosis | Defective mucus production |
| X-linked Recessive | Mutated gene on X chromosome | Hemophilia A | Impaired blood clotting |
Conclusion
Single-gene mutation disorders pose significant challenges to human health and well-being. Advancements in genetic technologies offer hope for improved diagnosis and potential therapies. However, it’s crucial to address the ethical implications of these technologies to ensure equitable access and responsible use. Continued research and public awareness are essential to mitigate the impact of these disorders and support individuals and families affected by them.
Answer Length
This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.