EVALUATION OF THE HUMAN HAIR ROOT FOR DNA TYPING SUBSEQUENT TO MICROSCOPIC COMPARISON

Telogen human hairs are one of the most common useful evidence finding s at crime scenes and/or on homicide victims. Occasionally, the micros copic characterization of the found telogen hair is the only physical evidence association to a victim or suspect. Recently efforts to chara cterize these hairs by mitochondrial DNA (mtDNA) methods have progress ed. The nature of the telogen hair root morphology and ultrastructure has, however, been largely ignored. Examiners have recognized these ha irs are unlikely to be typable by nuclear DNA (nuDNA) methods. Most fo rensic biologists have little knowledge of the complex cellular compos ition of anagen, catagen, and telogen hair roots or their morphogenesi s. This paper reviews ex situ human hair root morphology as it relates to the likelihood of successful nuclear DNA typing. Dermatology texts of hair root morphology always demonstrate their microscopic appearan ce in the skin. This study investigates the use of fluorescence in sit u hybridization (FISH) methods to sex type telogen head hairs, and it further investigates hair root morphology as it relates to the potenti al nuclear DNA content of evidence hairs. There is a need for the use of appropriate, consensus terminology for describing hair root morphol ogy. There is also a need for standardized laboratory light microscopi c methods in evaluating a hair root for DNA typing. FISH was found to be an unsuitable technique for sex determination of telogen hair clubs . It was determined that anagen/catagen hair roots without translucent sheath material are excellent candidates for nuDNA PCR-based typing a nd that hairs with telogen club root material only should not be submi tted for nuDNA typing attempts.