Disease-Induced Anomalous Human Microsatellite DNA - Implication in Forensic DNA Typing

Area of Science:

• Forensic Science
• Genetics
• Pathology

Background:

• Short tandem repeat (STR) markers are standard in forensic science for analyzing biological samples.
• Cancerous tissues can exhibit genetic alterations like microsatellite instability (MSI) and loss of heterozygosity (LOH).
• These alterations can lead to misinterpreted STR profiles, posing challenges in forensic investigations.

Purpose of the Study:

• To review literature on STR typing in unusual sample types, focusing on tumor materials.
• To identify causes of STR alterations in cancerous tissues.
• To evaluate forensic STR markers in solid tumor tissues and assess potential misinterpretations.

Main Methods:

• Literature review of studies on STR typing in archival pathology and postmortem tissues.
• Analysis of genetic alterations (MSI and LOH) affecting STR profiles in tumor samples.
• Evaluation of commercial STR markers used in solid tumor tissues for forensic applications.

Main Results:

• STR typing of cancerous samples can yield misinterpreted profiles due to MSI and LOH.
• Complete LOH and MSI are identified as causes of false STR profiles.
• STR-associated events in unusual cases may not align with known biological or disease processes.

Conclusions:

• Forensic STR typing of tumor material, while rare, requires careful consideration due to potential genetic alterations.
• Inconsistent results can arise from different analysis methods and marker sets.
• Individual evaluation of tumor types is essential to avoid misinterpretations in forensic casework.