CFC DNA Analysis & Interpretation 2

Question 1

A forensic analyst obtains a DNA profile from a degraded sample with only 8 of 20 CODIS loci amplified. What is the most appropriate course of action?

Accepted Answer

Compare the partial profile and note the reduced statistical weight

Answer

Partial profiles can be compared, but the statistical weight is reduced and limitations must be clearly communicated in the report.

Question 2

Which phenomenon occurs when a smaller DNA allele is preferentially amplified over a larger allele during PCR, leading to apparent homozygosity?

Accepted Answer

Allelic dropout

Answer

Allelic dropout occurs when one allele in a heterozygous sample fails to amplify, often due to low template DNA or degradation.

Question 3

In forensic DNA analysis, what does the term 'mixture ratio' refer to?

Accepted Answer

The relative proportion of DNA contributed by each individual in a mixed sample

Answer

Mixture ratio describes the proportional contribution of each individual's DNA in a mixed sample, important for deconvolution.

Question 4

A forensic examiner observes a peak in a capillary electropherogram that is exactly one repeat unit smaller than a true allele. This artifact is called:

Accepted Answer

Stutter

Answer

Stutter artifacts are minor peaks one repeat unit smaller (or occasionally larger) than the true allele, caused by strand slippage during PCR.

Question 5

When conducting Y-STR analysis on a sexual assault evidence sample, what is a key limitation forensic examiners must acknowledge?

Accepted Answer

Y-STRs cannot distinguish between male relatives sharing the same patriline

Answer

Y-STRs are identical among all paternally related males, so a match cannot exclude a brother, father, or other male paternal relatives.

(CFC) Certified Forensic Consultant Practice Test

(CFC) Certified Forensic Consultant Practice Test

CFC DNA Analysis & Interpretation 2