Question

1. Write an essay on how population and/or family pedigree genetic studies use genetic markers to distinguish between DNA variation [Hint: you may wish to include a discussion on HWE, finding causative mutations responsible for a Mendelian disease and/or using SNPs in GWAS for complex traits/disorders].

Answer 1

A specific mutation in genes, chromosomes, or proteins; in form of changes during inheritance, may be neutral (with no effect), beneficial or harmful. These inherited changes, may be detected by genetic testing. Inherited alteration in a person’s genome may be potentially harmful, when they may be factor for diseases running in a family.

In such cases, genetic testing may be applied to detect DNA, RNA, or protein of an individual, to observe and analyse:

1. Genetic mutation

2. genotypes related to the disease

3. phenotypic alterations

4. karyotypes.

Example: Considering an autosomal dominant genetic disease, which is caused by mutation in a single copy of gene form a parent in a family. This disease is referred to as e FAD or early onset of Familial Alzheimer Disease.

If genetic testing is done (even when the individual is asymptomatic), it will help in detection of the presence of e FAD gene, how it may affect in near future, weather the defect will be present in the progeny.

• GWAS is Genome wide association studies.
• It includes identification of genetic risk loci or genitically predisposed to the diseased condition.
• Cohort studies are conducted to gain knowledge about genetic influence, similar environmental factors influencing, ethnicity etc.
• GWAS allows identification of the candidate genes and polymorphic loci that are associated with the diseases.
• Genome sequencing use of microarrays, and other advanced genotyping technologies are applied.
• Bioinformatics is applied to form databases related to the genes for access during treatment.

Marker may include:

a. Restriction length polymorphism (RFLPs).

b. Simple sequence length polymorphism (SSLPs)- minisatellites or VNTRs (Variable numbers of tandem repeats), microsatellites or STRs (short tandem repeats).

c. Single nucleotide polymorphism (SNP).