Mitochondrial DNA Amplification Success Rate as a Function of Hair Morphology

• NCJ Number: 217214
• Author(s): Katherine A. Roberts Ph.D., Cassandra Calloway M.S.
• Date Published: January 2007
• Length: 8 pages
• Agencies: NIJ-Sponsored

Annotation

This study examined the amplification success rate of mitochondrial DNA for human head hair using a standard for forensic application.

Abstract

The study found a positive correlation between amplification success and the presence of a telogen hair root (root obtained in hairs released from the scalp through combing or brushing). Combining the amplification success with either the original or optimized protocol, telogen hairs resulted in an overall success rate of 77.5 percent compared with 65 percent for hairs with no roots. Controlling for telogen hairs, the overall success rate was not affected by cosmetic hair treatments; medulla structure; shaft length, diameter, and volume; and the location of the hair on the scalp. In contrast, the donor's age, race, and hair pigmentation all contributed to a variation in the amplification success rate. A lower amplification success was obtained for heavily pigmented hairs compared with lighter pigmented hairs. Hairs from Caucasians showed a significantly higher success rate (86.9 percent) compared with African-Americans (52.5 percent). Also, there was a positive correlation between older age groups and amplification success. The study amplified 2,554 head hairs from 132 individuals from 4 population groups. A total of 1,251 hairs were identified microscopically as telogen hairs (with roots), and 1,303 were classified as hairs without roots. Amplification success was assessed as a function of several independent variables: morphological characteristics (obtained from a dead or living person), telogen root versus no root, donor age, scalp origin, use of cosmetic hair treatment, and donor's race. 6 tables and 35 references