What are Genetic Disorders and Diseases? | SHE-ensya Lecture Series (Genetics and Molecular Biology)

Summary

This video lecture delves into genetics and molecular biology, exploring genetic disorders and their causes. It covers how viruses can cause temporary somatic mutations and the inherited genetic conditions in germ cells. The video explains single-gene disorders, chromosomal abnormalities, and multifactorial diseases, using examples like sickle cell anemia, cystic fibrosis, Huntington's disease, and Down syndrome. Additionally, it discusses modern biotechnology's role in addressing these disorders, emphasizing treatments and the ongoing search for cures. The lecture aims to enhance understanding of the complex nature of genetic diseases and their impact on human health.

Takeaways

• 😀 Viruses cause temporary mutations in the body, known as somatic mutations, which don't get passed on to future generations.
• 😀 Genetic disorders are often caused by mutations in the germ cells (sex cells), and these can be passed on to children and future generations.
• 😀 Three general types of genetic disorders exist: single-gene disorders, chromosomal disorders, and multifactorial disorders.
• 😀 Single-gene disorders can arise from mutations like substitution, insertion, or deletion in a gene, leading to changes in protein production.
• 😀 Examples of single-gene disorders include sickle cell anemia, cystic fibrosis, and Huntington's disease.
• 😀 Chromosomal disorders occur when entire chromosomes or portions of chromosomes are missing, added, or altered, leading to conditions like trisomy 13 and Down syndrome.
• 😀 Trisomy 13 (Patau syndrome) is a chromosomal condition that leads to severe developmental issues and a high infant mortality rate.
• 😀 Multifactorial disorders, such as Crohn's disease and diabetes, are influenced by both genetic factors and environmental factors like diet and lifestyle.
• 😀 Diabetes is a metabolic disorder where the body struggles to produce or use insulin, leading to high blood sugar and other serious health issues.
• 😀 Modern biotechnology seeks to find cures for genetic disorders, with the ultimate goal being to improve lives by correcting genetic mutations at the molecular level.

Q & A

What are somatic mutations and how do they differ from germline mutations?

Somatic mutations are changes to the DNA that occur in non-reproductive cells, and they are not passed on to future generations. In contrast, germline mutations occur in reproductive cells (sperm or egg) and can be inherited by offspring.

How do viruses cause genetic mutations in human cells?

Viruses can alter the genome by hijacking the molecular processes of a cell. They inject their DNA or RNA into host cells, temporarily integrating their genetic material, which can cause mutations in the host genome or transcriptome.

What is the difference between substitution mutations and insertion/deletion mutations?

Substitution mutations involve replacing one nucleotide with another, which may or may not affect the protein. Insertion and deletion mutations involve the addition or removal of nucleotides, which can lead to frameshift mutations that significantly alter the protein product.

What is a frameshift mutation, and how does it affect proteins?

A frameshift mutation occurs when nucleotides are inserted or deleted in a way that shifts the reading frame of the gene. This changes every amino acid in the protein from the point of mutation onward, often resulting in a dysfunctional or nonfunctional protein.

How does sickle cell anemia occur at the genetic level?

Sickle cell anemia is caused by a mutation in the hemoglobin beta gene, leading to abnormal hemoglobin molecules (hemoglobin S). These molecules stick together and form rod-like structures, causing red blood cells to become stiff and take on a sickle shape, which can block blood flow and damage organs.

What are the symptoms and causes of cystic fibrosis?

Cystic fibrosis is caused by a mutation in the CFTR gene, leading to the buildup of thick, sticky mucus that can damage many organs. Symptoms include respiratory issues, chronic digestive problems, and progressive lung damage.

What is Huntington’s disease and how does it affect individuals?

Huntington’s disease is a neurodegenerative disorder caused by a mutation in the HTT gene. It leads to the progressive breakdown of nerve cells in the brain, resulting in motor and cognitive decline, with symptoms typically appearing between the ages of 30 and 50.

What types of chromosomal mutations can lead to genetic disorders?

Chromosomal mutations can include deletions (loss of a chromosome segment), duplications (copying of a segment), inversions (flipping a segment), and translocations (rearrangement of chromosome parts). These mutations can disrupt the structure or number of chromosomes, leading to disorders like trisomy 13 or Down syndrome.

What is trisomy 13, and what are its key features?

Trisomy 13, also known as Patau syndrome, is a chromosomal condition where an individual has three copies of chromosome 13. It is associated with severe developmental and physical abnormalities, including heart defects, brain or spinal cord issues, and extra fingers or toes. Most infants with trisomy 13 do not survive beyond their first year.

How do multifactorial genetic disorders differ from single-gene and chromosomal disorders?

Multifactorial disorders arise from the interaction of multiple genes and environmental factors, making their inheritance patterns complex. Unlike single-gene disorders, which are caused by mutations in one gene, or chromosomal disorders, which involve changes in chromosomes, multifactorial disorders are influenced by a mix of genetics and lifestyle factors.

What is Crohn’s disease, and what factors contribute to its onset?

Crohn’s disease is an inflammatory bowel disease that causes symptoms like abdominal pain, diarrhea, and malnutrition. Its onset is influenced by a combination of genetic factors, diet (especially high in processed foods), smoking, and excessive antibiotic use.