A forensic scientist receives a degraded bone sample from a mass disaster. Autosomal STR profiling fails due to degradation. The preferred next-step molecular technique to attempt identification by maternal lineage comparison is:

• A Y-chromosome STR haplotyping
• B Single nucleotide polymorphism (SNP) array on nuclear DNA
• C X-chromosomal STR typing
• D Mitochondrial DNA hypervariable region (HV1/HV2) sequencing ✓

Explanation

Mitochondrial DNA is present in hundreds to thousands of copies per cell, making it recoverable even from severely degraded and ancient bone. Sequencing the hypervariable regions HV1 and HV2 of the D-loop permits comparison with living maternal relatives, enabling maternal lineage-based identification. Y-STR typing traces paternal lineage only and is useless for maternal identification. Nuclear SNP arrays also fail with severe degradation. X-chromosomal STRs have low copy number like autosomal STRs.

Reference: The Essentials of Forensic Medicine and Toxicology (Narayan Reddy), 34th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.