ABC Forensic DNA study guide
ABC Forensic DNA · Work through your exam, one topic at a time.
The American Board of Criminalistics (ABC) describes certification as a voluntary process of peer review through which a practitioner is recognized as having attained the professional qualifications necessary to practice in one or more disciplines of criminalistics. Forensic DNA (DNA) is one of the ABC's certification examinations and one of the scopes listed under its accreditation ID 9106, alongside biological evidence screening, foundational knowledge, and seized drug analysis. The ABC Forensic DNA study guide has 5 sections and about 1,442 words.
01Biological Evidence Screening and Sample Selection
Screening asks three questions: what biological material is present, where is it, and which portion should be sampled for DNA. Presumptive tests such as luminol, Kastle-Meyer, TMB, acid phosphatase, alpha-amylase, and PSA indicate a class of substance but are not identity tests.
306 words, about 2 min02DNA Extraction, Quantitation, and Amplification
Cell lysis releases DNA; proteinase K digests protein, DTT breaks disulfide bonds in sperm heads, and detergents solubilize membranes. Silica and magnetic bead methods bind DNA under chaotropic conditions; organic extraction uses phenol-chloroform; Chelex is rapid but crude.
313 words, about 2 min03STR Typing and Capillary Electrophoresis
STR alleles are named by the number of repeat units; microvariants fall between integer bins. Multiplex kits amplify many loci with dye-labeled primers.
259 words, about 1 min04Profile Interpretation, Mixtures, and Statistical Calculations
Start with the number of contributors, then assess peak balance, allele sharing, and stochastic effects. A single-source profile should show no more than two alleles per locus and reasonable peak height ratios; tri-allelic patterns and imbalanced peaks suggest mixtures or artifacts.
265 words, about 1 min05Quality Assurance, Quality Control, and Legal/Reporting Requirements
Accreditation to ISO/IEC 17025 and adherence to FBI QAS and SWGDAM standards require document control, validated methods, calibrated instruments, and trained, competency-tested analysts. Internal validation establishes sensitivity, precision, reproducibility, mixture detection, and contamination limits before a method is used on casework.
299 words, about 1 min