Question

A characteristic of modern genetic research is a. that very few candidate genes are proposed for any given disorder b. that positive association studies of candidates have been consistently replicated c. all of the above d. none of the above

Short answer

a. very few candidate genes are proposed for any given disorder b. positive association studies of candidates have been consistently replicated c. all of the above d. none of the above Answer: d. none of the above

Step-by-step solution

Understanding the terms in the question

First, make sure you know what each of the following terms and concepts mean: candidate genes, association studies, and replication. A candidate gene is a gene whose function or location suggests it might contribute to a particular disorder or trait. Association studies seek to identify links between genetic variants and particular traits or diseases by analyzing populations. Replication means that an experiment's findings can be reliably repeated and consistently observed by other researchers.

Analyzing each statement

a. that very few candidate genes are proposed for any given disorder - This statement is not true. In modern genetic research, due to the advances in technology and our increased understanding of genetics, numerous candidate genes can be proposed or investigated for any given disorder. b. that positive association studies of candidates have been consistently replicated - This statement is also not true. Although replication is an essential aspect of genetic research, not all positive association studies can be consistently replicated. c. all of the above - This option is incorrect since neither a nor b can be considered as characteristic of modern genetic research. d. none of the above - This option means none of the given statements, a, b, or c, are true concerning modern genetic research.

Select the correct answer

Out of the four options, option 'd. none of the above' is the correct answer, as none of the statements provided accurately describe a characteristic of modern genetic research.

Key concepts

Candidate Genes

In modern genetics, candidate genes are carefully selected based on their presumed relevance to specific disorders or traits. This selection is often grounded in prior knowledge about gene function, gene expression patterns, or the physical location within the genome.

Early research methods led scientists to hypothesize about a small number of potential candidate genes, but advancement in genomic technologies has broadened this approach significantly. Now, researchers can explore hundreds or even thousands of candidate genes at once through high-throughput sequencing methods. This abundance does not guarantee that a proposed gene will be directly linked to a disorder, but it does provide a larger pool from which scientists can draw hypotheses.

For instance, suppose scientists are studying a genetic disorder such as cystic fibrosis. Early studies might have focused on a handful of genes known to affect lung function. With modern techniques, however, a broader range of genes is often implicated, including those involved in cellular transport mechanisms, ion channels, and more.

Association Studies

The technique of association studies lies at the heart of modern genetic research. Unlike candidate gene studies that start with a gene and look for an association with a disease, association studies often look broadly across the genome to identify any potential links between genetic variations and specific traits or diseases.

Genome-Wide Association Studies (GWAS)

One widely used form of association study is the Genome-Wide Association Study (GWAS), where researchers examine genetic markers across the complete sets of DNA, or genomes, of many people to find genetic variations associated with a particular disease. These studies are particularly useful in identifying genetic variants that contribute to common, complex diseases such as heart disease, diabetes, and psychiatric disorders.

Results from GWAS can suggest novel biological pathways involved in disease and can highlight potential targets for new therapies. They can also provide insights into the genetic basis of response to treatment, paving the way for personalized medicine.

Replication in Genetics

In the context of genetics, replication refers to the confirmation of research findings through independent studies. Reliable replication is crucial for establishing the validity of genetic associations and for confirming the role of candidate genes in disease.

However, replication is challenging. Positive results in genetics may arise by chance due to the vast number of genetic markers tested. Other factors such as population differences, environmental interactions, and experimental design can also influence replicability.

For a finding to be considered robust, it must be replicated consistently across multiple studies, often involving different populations or methods. Replications solidify the confidence in genetic associations and are vital before findings can be applied clinically. Without successful replication, initial findings may lead to 'false positives,' creating misleading directions in the search for treatments or understanding of genetic diseases.