× Ø × Ø × Ø × Ø × Ø × Ø × Ø × Ø × Ø × Ø × Ø × Ø × Ø × Ø × Ø

Since 1994, the DNA Identification Laboratory at the Armed Forces Institute of Pathology has entered over 1100 sequences representing four major racial groups (African, Asian, Caucasian, and Hispanic) into its mitochondrial DNA (mtDNA) database. The African database includes African (Sierra Leone), African-American, and Afro-Caribbean groups. Likewise, the Asian database includes Chinese, Japanese, and Vietnamese. Persons from Austria, Britain, and the United States are represented in the Caucasian database, which will be expanded to include Croatian and French populations in the near future. Hispanic population information is both from within and outside of the United States.

Mitochondrial DNA sequence information generated from in-house casework is compared to all entries in the database to determine the number of consistent sequences present. The number of times a sequence has been observed in each of the four major racial groups, as well as the total number of observances, is reported. Currently, no frequencies or probabilities are given. Upon expansion of the database (i.e., once there are greater than 500 entries for a specific racial group), it will be possible to say that 99% of the general population can be excluded at a 95% confidence level when a mtDNA sequence is not consistent with any found in that specific racial group. In addition to in-house casework, requests for database searches from outside agencies are accepted and reported in the same manner.

The mitochondrial DNA sequence database will provide a means to make comparisons both among and between racial groups and to support indications of population substructuring. Based on the limited database at present, it appears as if the majority of differences in the polymorphism frequency distribution are greater between racial groups as spposed to within a group. This is consistent with population database statistics derived from nuclear DNA testing.

The DNA Identification Laboratory at the Armed Forces Institute of Pathology has been designated to establish a forensic mitochondrial DNA sequence database for use by the international community. Sequence information from other sources will be entered into the existing database after meeting several criteria, including analysis of the data in a manner that conforms to standard procedure at this laboratory. A critical aspect of this procedure is the independent analysis of the data by two scientists. Once submitted, the mtDNA sequence information will b reviewed by scientists in-house before being entered into the database.

The importance of mtDNA sequence analysis to forensic casework dictates the need for a central database that is easily accessible, but secure and accurate as well. It is anticipated that the DNA Identification Laboratory at the Armed Forces Institute of Pathology will become such a resource for the forensic community.