Genetic Variation and Disease ~Direct-to-Consumer Genetic Testing~ (23andMe)

Summary

This video explains the concept of direct-to-consumer (DTC) genetic testing, highlighting the role of DNA variations in human traits and disease susceptibility. It distinguishes between monogenic diseases, caused by mutations in a single gene, and polygenic conditions, influenced by multiple genes. The script discusses how genetic testing can identify both types of conditions, with DTC tests providing insights into risk factors, which may lead to healthier lifestyle choices and early monitoring. It also stresses the importance of consulting healthcare providers for comprehensive testing, particularly for rare genetic conditions within families.

Takeaways

• 😀 DTC genetic testing looks for variations in a person's DNA to provide insights into traits and disease risks.
• 😀 DNA consists of nucleotides (sugar, phosphate, and bases: adenine, thymine, guanine, and cytosine), which form genes that can have variations.
• 😀 Genetic variations, or mutations, can be as small as a single nucleotide, referred to as a SNP (Single Nucleotide Polymorphism).
• 😀 Genotyping and DNA sequencing are common molecular techniques used to detect genetic variants.
• 😀 Genetic diseases can be monogenic (caused by a variant in a single gene) or polygenic (influenced by many genes).
• 😀 Monogenic diseases are usually rare, inherited in predictable patterns, and can be managed with medical guidelines to reduce risk.
• 😀 Familial hypercholesterolemia is an example of a monogenic condition caused by a variant in a single gene, leading to high LDL cholesterol and increased heart disease risk.
• 😀 In monogenic diseases, the same variant may cause different severity levels across family members, a phenomenon called variable expressivity.
• 😀 Polygenic diseases, like common health conditions (e.g., high cholesterol), result from multiple genetic factors and environmental influences.
• 😀 Polygenic risk scores, derived from genetic testing, can predict the likelihood of developing certain conditions and guide health monitoring and lifestyle choices.

Q & A

What is Direct-to-Consumer (DTC) genetic testing?

Direct-to-Consumer (DTC) genetic testing involves testing for variations in a person's genome, which is made up of DNA. It provides insights into a person's genetic makeup and can indicate predisposition to certain traits or diseases.

What are the basic building blocks of DNA?

The basic building blocks of DNA are called nucleotides, which consist of a sugar-phosphate backbone and one of four bases: adenine, thymine, guanine, and cytosine.

What is a genetic variant?

A genetic variant refers to a change or mutation in the DNA sequence. These variants can be small, like a single nucleotide (known as a SNP or single nucleotide polymorphism), and can contribute to differences in traits or susceptibility to diseases.

What is genotyping and how is it used in genetic testing?

Genotyping is a method used in genetic testing to identify specific variants of interest in a person's DNA. It typically uses DNA microarrays to detect variations in genetic sequences.

How does DNA sequencing differ from genotyping?

DNA sequencing involves determining the exact order of nucleotides in a continuous section of DNA, whereas genotyping identifies specific variants or mutations in the genome.

What are monogenic diseases?

Monogenic diseases are caused by a single genetic variant in one gene and are usually inherited in a predictable pattern, such as autosomal dominant or recessive inheritance.

What is the significance of autosomal dominant inheritance in monogenic diseases?

In autosomal dominant inheritance, a single variant in one gene is enough to cause the disease. This means that an individual with one copy of the variant is at risk of developing the condition.

What is the difference between variable expressivity and non-penetrance in monogenic diseases?

Variable expressivity refers to differences in the severity of the disease caused by the same genetic variant in different individuals. Non-penetrance occurs when the genetic variant does not cause the disease at all, potentially due to environmental or other genetic factors.

What is polygenic inheritance?

Polygenic inheritance involves multiple genetic variants, each contributing a small effect. These variants together influence the risk of complex conditions, such as high cholesterol, without following a specific inheritance pattern.

How do genome-wide association studies (GWAS) help in understanding polygenic conditions?

GWAS help identify variants that are more common in affected individuals compared to unaffected ones. These studies provide insights into the genetic contribution to complex conditions by examining multiple genetic variants across the genome.