Population data on nine STR loci in an El Salvadoran (Central American) sample population.
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Biomedical subjects
Publications and source records attributed to C Entrala.
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In 1999, Spain was the first country to officially start a National Program to try to identify cadavers and human remains which could not be identified by the use of traditional forensic approaches. This attempt is called "Phoenix Program". Two independent mitochondrial DNA (mtDNA) databases were generated, which can automatically compare and match identical or similar sequences. One is the Reference Database, with mtDNA sequences from maternal relatives of missing persons, who provide the samples (buccal swabs) voluntarily; the other is the Questioned Database, comprised of mtDNA data of unknown remains and cadavers. Although the first phase of the program (typing of all unidentified human remains) will probably not be completed until December 2003, positive identifications are being made in the interim. To date, more than 1,200 families have contacted Phoenix, and at least 280 reference samples and 48 questioned evidences have been analyzed. When mtDNA matches are found, another independent analysis is performed as a part of the quality control mechanism. Once a match is confirmed (so far in 6 cases), an attempt is made to analyze short tandem repeat (STR) loci. We call for international collaboration to make this effort valuable worldwide.
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A set of 212 samples from unrelated Spanish Caucasians living in Andalucia (southern Spain) were analyzed with a new commercially-available kit for multiplex amplification of 3 STR loci (D13S137, D7S820, and D16S539), manual denaturing polyacrylamide gel electrophoresis and silver staining. These three loci are of special interest for the forensic community since they are a part of the 13 CODIS-core STR loci. The results show that the loci D13S317 and D16S539 meet Hardy-Weinberg expectations (HWE), but the locus D7S820 did not meet HWE (p = 0.003). However, there was no detectable departures from independence (i.e., linkage disequilibrium) between any pair-wise combination of loci. The D7S820 data were further investigated. The excess homozygosity was due to an excess of D7S820 10, 10 homozygotes. To determine if the allele frequency data are meaningful and can be applied to forensic identity cases, the Spanish D7S820 allele frequency data were compared with four other Caucasian sample populations. The D7S820 allele frequencies were statistically similar; thus, the results support that the allele frequency data can be used reliably for estimating DNA profile frequencies.
A total of 171 Caucasians living in Andalucia (southern Spain) have been typed for nine short tandem repeat (STR) loci by multiplex PCR amplification using a commercially available kit (Profiler Plus; Perkin-Elmer, Norwalk, CT, USA) and semi-automatic electrophoresis (ABI Prism 377 DNA Sequencer, Applied Biosystems, Foster City, CA, USA). The kit enables typing of the STR loci D3S1358, VWA, FGA, D5S818, D13S317, D7S820, D8S1179, D21S11, and D18S51. All loci, except D7S820, meet Hardy-Weinberg equilibrium. Because of the large number of loci that can be analyzed, the power of discrimination (PD) is greater than 0.99999, and the probability of exclusion (PE) reaches 0.99991 in our population sample.
Dandruff is a clinical alteration of the skin that consists histologically of orthokeratotic clumps with minute parakeratotic foci found in inflammatory pathologies such as seborrheic dermatitis and psoriasis. Therefore, some nucleated cells should be found in dandruff and hence there is a possibility that forensically typeable DNA could be extracted from dandruff. Because of a particular case in which we were involved, a study was carried out to determine whether or not DNA could be extracted from dandruff, and if the two most widely used extraction techniques (Chelex and organic) would be applicable. Results show that sufficient quantities of DNA (more than 30 to 40 ng) can be obtained from as little as 1.0 to 1.5 mg of dandruff. Both methods yield DNA, although the organic procedure seems to yield more (72.5 ng Chelex vs. 183.3 ng organic). All the DNA samples extracted were typed correctly for the loci HUMTH01 and HUMvWA. Therefore, dandruff can be considered a potential source of DNA for forensic identification.