Mitochondrial DNA Variation in Human Hair Shafts Influenced by Physical Characteristics: A Massively Parallel Sequencing Analysis

This study analyzed mitochondrial DNA (mtDNA) in 907 hair shaft fragments from 183 donors using massively parallel sequencing to explore how physical characteristics of hair shafts affect mtDNA metrics. Results indicated that longer and black hair shafts produced higher mtDNA read counts, while segmented hairs showed decreasing read counts and increasing degradation from proximal to distal ends. Cosmetic treatments influenced point heteroplasmy (PHP) type and distribution but did not consistently affect mtDNA read counts or degradation. These findings suggest associations between hair shaft characteristics and mtDNA metrics, with potential forensic applications, though further validation with larger datasets is needed.