Question

Which of the examples of genetic testing below are prognostic tests? Which are diagnostic? (a) Individual sequencing (personal genomics) identifies a mutation associated with Alzheimer's disease. (b) ASO testing determines that an individual is a carrier for the mutant \(\beta\) -globin allele \(\left(\beta^{S}\right)\) found in sickle-cell anemia. (c) DNA sequencing of a breast tumor reveals mutations in the BRCA1 gene. (d) Genetic testing in a healthy teenager identifies an SNP correlated with autism. (e) An adult diagnosed with Asperger syndrome (AS) has a genetic test that reveals a SNP in the GABRB3 gene that is significantly more common in people with AS than the general population.

Short answer

a) Identifying a mutation associated with Alzheimer's disease b) ASO testing for sickle-cell anemia c) DNA sequencing of a breast tumor for BRCA1 gene d) Genetic testing for an SNP correlated with autism e) Testing for SNP in GABRB3 gene in an adult with Asperger syndrome Answer: a) Prognostic b) Diagnostic c) Both diagnostic and prognostic d) Prognostic e) Diagnostic

Step-by-step solution

Example (a) : Identifying a mutation associated with Alzheimer's disease

This test is checking for a mutation that might indicate an individual could develop Alzheimer's disease in the future. This is a prognostic test, as it is predicting the likelihood of developing the disease.

Example (b) : ASO testing for sickle-cell anemia

This test is determining if an individual is a carrier of the mutant allele, which can lead to sickle-cell anemia. Being a carrier means that the individual may not necessarily have the disease but could pass it on to their offspring. This test is diagnostic, as it provides information about the presence of a mutation that is associated with a disease.

Example (c) : DNA sequencing of a breast tumor for BRCA1 gene

This test is looking at the DNA of a breast tumor to find mutations in the BRCA1 gene. This helps to determine the type of breast cancer as well as the likelihood of the cancer returning or spreading. This test is a combination of diagnostic (identifying the presence of a mutation in a tumor) and prognostic (predicting cancer progression).

Example (d) : Genetic testing for an SNP correlated with autism

In this case, the test is looking for an SNP in a healthy teenager that is correlated with autism. Since the teenager is currently healthy, this test is predicting the likelihood of developing autism in the future. This is a prognostic test.

Example (e) : Testing for SNP in GABRB3 gene in an adult with Asperger syndrome

In this scenario, the individual has already been diagnosed with Asperger syndrome. The genetic test is used to find an SNP in the GABRB3 gene, which is more common in people with Asperger syndrome. This test is diagnostic because it is used to confirm the presence of a mutation associated with the already diagnosed condition.

Key concepts

Prognostic Tests

Understanding prognostic tests is essential for grasping the scope of genetic testing. These tests assess the likelihood of an individual developing a disease or disorder in the future. For instance, when a genetic test identifies a mutation linked with Alzheimer's disease, it functions as a prognostic test since it predicts the individual's risk of developing this condition. Prognostic tests do not necessarily confirm the presence of a disease but highlight the increased probability of its occurrence, allowing for early intervention or the opportunity to manage risk factors.

These tests are invaluable in managing patient care and can guide clinical decisions, including the type of surveillance or preventative measures that could be beneficial. By understanding the personal risk profile, an individual can make informed decisions about their health and lifestyle.

Diagnostic Tests

Diagnostic tests serve a critical role in healthcare; they are employed to confirm the presence of a disease or a genetic condition. For example, ASO testing, which determines if someone carries a mutation for sickle-cell anemia, exemplifies a diagnostic test because it identifies a specific, existing condition. Additionally, when a genetic test reveals a mutation in the GABRB3 gene in a person already diagnosed with Asperger syndrome, it's also diagnostic, serving as a confirmation of the diagnosis.

These tests can influence treatment decisions, determine the need for family counseling on inheritable diseases, or guide further testing. As educational aids, they help students distinguish between tests for diagnosis and those predicting future risk, emphasizing the importance of context in interpreting genetic test results.

Personal Genomics

Personal genomics is an exciting area of genetic testing that provides individuals with information about their genome. It includes comprehensive analyses, like those identifying mutations associated with Alzheimer's or SNPs correlated with conditions like autism. The field of personal genomics has expanded with technology advancements, allowing for individualized insights into genetic health risks, ancestry, and response to certain medications.

The educational potential of personal genomics lies in its power to personalize learning about genetics. As students see how their genetics might impact their own lives, their engagement and understanding of the subject matter can significantly increase. This individual-oriented approach to genetics underscores the broader implications of genetic research on personal healthcare.

SNP (Single-Nucleotide Polymorphism)

Single-nucleotide polymorphisms, commonly known as SNPs, are a topic of interest in genetic studies and a key concept in personalized medicine. They are variations in the DNA sequence occurring when a single nucleotide in the genome differs between individuals or paired chromosomes. SNPs can be linked to disease susceptibility, response to drugs, and physical traits.

For example, identifying an SNP in the GABRB3 gene which is associated more frequently with Asperger syndrome increases our understanding of the genetic factors involved in the condition. Educational resources on SNPs can use these examples to demonstrate the application of genetics in medicine and the importance of SNPs in understanding and managing health risks. By learning about SNPs, students can better appreciate the complexities of genetic variation and its influence on human health.