Genetic variations

What defines a DNA polymorphism?

A DNA sequence variation occurring in ≥1% of the population

What is the difference between a mutation and a polymorphism?

A mutation is a rare DNA change (<1%), while a polymorphism is common (≥1%).

What type of DNA variation involves single base changes?

Point mutations (e.g., substitutions, insertions, deletions).

What causes most microsatellite (STR) polymorphisms?

DNA polymerase slippage during replication.

What are VNTRs?

Variable Number Tandem Repeats – longer repeat units (up to 25 bp), used in DNA profiling.

Why are STRs preferred in forensic analysis?

Short repeat units make them easy to amplify with PCR, even from degraded DNA.

What is an RFLP?

A DNA variation that alters restriction enzyme recognition sites, leading to different fragment lengths.

What is a neutral variant?

A DNA change that alters the amino acid but does not affect protein function.

Which database compiles SNP data and assigns rsIDs?

dbSNP.

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What does GWAS stand for, and what does it do?

Genome-Wide Association Study – links SNPs to traits/diseases in large populations.

What are LINEs and SINEs?

Interspersed repeats derived from transposable elements.

What was a goal of the HapMap Project?

To catalog common haplotypes and SNPs across global populations.

What are the four main types of DNA polymorphisms?

RFLPs, SNPs, VNTRs, STRs.

What are Copy Number Variations (CNVs)?

DNA segments >1 kb that vary in copy number compared to a reference genome.

Which diseases are associated with CNVs?

Autism, cancer, and certain benign conditions with no apparent clinical symptoms.

Which techniques are commonly used to detect CNVs?

Array-CGH and Next Generation Sequencing (NGS).

What does aCGH stand for and what does it detect?

Array Comparative Genomic Hybridization; detects CNVs.

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What causes trinucleotide expansions like in Huntington's disease

Replication slippage leading to expansion of repeat units (e.g., CAG).

What is MLPA and what is it used for?

Multiplex Ligation-dependent Probe Amplification; used to detect deletions/duplications

What are two types of mutation detection approaches?

Direct (e.g., sequencing) and Indirect (e.g., SSCP, dHPLC).

What is a common PCR error that can lead to false results?

Allelic drop-out or misincorporation of bases.

In forensic DNA analysis, which markers are typically used?

STRs (Short Tandem Repeats).

What is the practical use of DNA variation in medical analysis?

Risk prediction, early diagnosis, personalized medicine, and drug development.

What is the gold standard for detecting single base changes?

DNA sequencing.

Name one tool used to study genome structure

Genome browsers like Ensembl or UCSC Genome Browser.

What does the tier-based classification of somatic variants indicate?

Clinical significance in diagnosis, prognosis, or therapy.

What types of biological databases exist?

Nucleic acid, protein, structure, and genomic databases