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Two hundred twenty-five unrelated males were typed for 7 over 8 loci Y-chromosome STRs proposed in a collaborative study by The Spanish and Portuguese ISFG Working Group. The markers amplification were in two multiplex reactions GEPY I with GATA C4, DYS438, DYS437, DYS461 (GATA A7.2) and GEPY II with GATA H4, DYS439, GATA A10 and DYS460 (GATA A7.1). All gene diversities were upper 0.5 with the highest value in DYS439 with 0.64. Furthermore, 152 haplotypes from 7 loci Y-chromosome STRs were found within studied population and a high haplotype diversity 0.9902 was found. The DYS460 (GATA A7.1) marker can not be studied because its diverse alleles were not able for interpret.

Three hundred and twenty-six to four hundred and fifty-one individuals were typed for 12 STR markers and revealed by silver stain method and assisted by a computer analysis. Forensic and Hardy-Weinberg values were found. The Kodak ds 1D Image Analysis Software V 2.0.3 EDAS DC 120 System was a useful tool for determining the correct size of pattern bands that were out allelic ladders, alleles 18 and 17 from F13A01, 15 from TPOX and 4 from TH01 were determined by this method and some corroborated by automatic analysis.

A collaborative exercise was carried out by the Spanish and Portuguese ISFG Working Group (GEP-ISFG) in order to evaluate the performance of two Y-chromosome STR PCR tetraplexes, which include the loci DYS461, GATA C4, DYS437 and DYS438 (GEPY I), and DYS460, GATA A10, GATA H4 and DYS439 (GEPY II). The participating laboratories were asked to type three samples for the eight markers, using a specific amplification protocol. In addition, two control samples, with known haplotypes, were provided. The results obtained by the 13 different participating laboratories were identical, except for two laboratories that failed to type correctly the same two samples for GATA C4. By sequence analyses, two different GATA C4 allele structures were found. One control sample (allele 21) and two questioned samples (allele 22, correctly typed by all the laboratories, and allele 25) presented the following repeat structure: (TCTA)4(TGTA)2(TCTA)2(TGTA)2 (TCTA)n, but different from the one found for allele 26 in one sample included in this exercise, as well as in the second control sample (allele 23), namely (TCTA)4(TGTA)2(TCTA)2(TGTA)2 (TCTA)2(TGTA)2(TCTA)n. The collaborative exercise results proved that both Y-tetraplexes produce good amplification results, with the advantage of being efficiently typed using different separation and detection methodologies. However, since GATA C4 repeat presents a complex structure, with alleles differing in sequence structure, efficient denaturing conditions should be followed in order to avoid typing errors due to sizing problems. © 2003 Elsevier Ireland Ltd. All rights reserved.