STP Genomics & Molecular Biology 3

Question 1

Epigenetics refers to changes in gene expression that are:

Accepted Answer

Heritable changes in gene activity not involving changes to the underlying DNA sequence

Answer

Epigenetic modifications, including DNA methylation and histone modification, regulate gene expression heritably without altering the DNA sequence itself.

Question 2

In the clinical genomics laboratory, variant interpretation follows which internationally recognised classification system?

Accepted Answer

The ACMG/AMP five-tier variant classification (Pathogenic to Benign)

Answer

The American College of Medical Genetics and Genomics (ACMG)/AMP 2015 guidelines provide a five-tier system (Pathogenic, Likely Pathogenic, VUS, Likely Benign, Benign) widely used in clinical genomics reporting.

Question 3

What is a microsatellite in the context of genomic analysis?

Accepted Answer

A short tandemly repeated sequence (1–6 bp repeat unit) distributed throughout the genome

Answer

Microsatellites (STRs) are tandem repeats of 1–6 bp units that vary in repeat number between individuals, making them informative markers for identity testing, linkage analysis, and MSI assessment.

Question 4

Bioinformatics pipelines in clinical genomics typically include which sequence of steps?

Accepted Answer

Base calling → alignment to reference genome → variant calling → annotation and filtering

Answer

Standard NGS bioinformatics pipelines convert raw signal to base calls, align reads to a reference genome, identify variants, then annotate and filter against databases and quality thresholds before clinical interpretation.

Question 5

Loss of heterozygosity (LOH) in tumour genomics indicates:

Accepted Answer

Loss of one allele at a locus, often revealing a recessive mutation in the remaining allele

Answer

LOH occurs when one allele at a heterozygous locus is deleted or otherwise lost in somatic cells; if the retained allele carries a pathogenic variant, it becomes unmasked, consistent with Knudson's two-hit hypothesis.

(STP) Scientist Training Programme Practice Test

(STP) Scientist Training Programme Practice Test

STP Genomics & Molecular Biology 3