Analysis of 16 autosomal STRs and 17 Y-STRs in an indigenous Maya population from Guatemala.

The aim of this study was to contribute new data on autosomal STR and Y-STR markers of the Mayas from Guatemala in order to improve available databases of forensic interest. We analyzed 16 autosomal STR markers in a population sample of 155 indigenous Maya and 17 Y-chromosomal STR markers in the 100 males of the sample. Deviations from Hardy-Weinberg equilibrium and linkage disequilibrium between autosomal STR markers were not observed at any loci. The combined power of exclusion was estimated as 99.9991% and the combined power of discrimination was >99.999999999999%. Haplotype diversity of Y-STRs was calculated as 0.9984 ± 0.0018 and analysis of pairwise genetic distances (Rst) supported the Native American background of the population.

Polymorphisms in alcohol and tobacco metabolism genes in head and neck cancer in the Basque Country.

BACKGROUND: The Basque Country has one of the highest rates of head and neck squamous cell carcinoma (HNSCC) in Europe, although tobacco and alcohol consumption are not high when compared to other European countries where HNSCC incidence is lower. Our aim was to determine the role of genetic variation with regard to the metabolism of alcohol and carcinogens from tobacco smoke in the Basque Country. METHODS: Fourteen polymorphisms in alcohol or tobacco metabolism genes were genotyped in 84 HNSCC patients and 242 healthy individuals from the Basque Country. RESULTS: ADH1B histidine allele (rs1229984), CYP2E1 rs3813867 heterozygous genotype, and GSTT1 deletion conferred protection against HNSCC (OR: 0.318 [0.04-0.75], OR: 0.13 [0.02-0.94], and OR: 0.12 [0.02-0.60], respectively) while GSTP1 (rs1695) Val/Val genotype was related to an increased risk (OR: 4.12 [1.11-15.31]). Regarding alcohol and tobacco habits, GSTT1 deletion was associated with tobacco usage, while the 3 polymorphisms tested in ALDH2 were associated with alcohol consumption. However, genotypic distributions of these 7 SNPs did not differ from those observed for other Caucasian populations where HNSCC incidence is lower. CONCLUSIONS: The identified genotypic variations in alcohol and tobacco metabolizing genes only by themselves do not seem to be responsible for the higher incidence of HNSCC observed in the Basque Country.

Study of six X-linked tetranucleotide microsatellites: population data from five Spanish regions.

We studied six X-linked microsatellites in a large group of Spanish individuals (n=614) from five different regions located in northern, central and southern Spain. All the markers had tetranucleotide repeat units (DXS9895, DXS9898, DXS7130, DXS7132, GATA172D05 and DXS6789). They were amplified in two triplex PCR reactions. There were no significant sex- or region-related differences in allelic frequencies, suggesting that general national databases can be adequate as a reference for X-linked markers. The analysis of those six short tandem repeats combined in 316 males revealed 300 different "temporary haplotypes", 283 of which were found only once. There was no evidence for statistically significant linkage disequilibrium among the loci studied. Therefore these markers are quite polymorphic and useful for forensic purposes.

No association between GSTP1 gene aberrant promoter methylation and prognosis in surgically resected hepatocellular carcinoma patients from the Basque Country (Northern Spain).

AIMS: Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide, being linked etiologically to several factors. Glutathione-S-transferases (GSTs) are a family of enzymes that play an important role in detoxification. Hypermethylation of regulatory sequences at glutathione-S-transferase pi class gene (GSTP1) has been found in different human tumor types. In this study, we have studied the methylation status of the GSTP1 promoter region in patients from the Basque Country (Northern Spain) by methylation-specific PCR (MSP). METHODS AND RESULTS: GSTP1 aberrant promoter methylation was present in 24 of 117 (20.5%) tumor samples being associated with late stages of tumor progression. Patients with multiple HCCs showed different patterns of methylation, which could suggest a different clonal origin of multicentric HCC or different degrees of differentiation. No effect on disease-free survival or overall survival was observed in patients with GSTP1 methylated who underwent curative resection. CONCLUSIONS: We can conclude that GSTP1 promoter CpG island methylation appears to be a less common event during hepatocarcinogenesis in European populations than in Asian populations, being associated with late stages of tumor progression. These findings could also be useful to provide new therapeutic strategies through the use of demethylating agents.

Frequent loss of p53 codon 72 Pro variant in hepatitis C virus-positive carriers with hepatocellular carcinoma.

Codon 72 exon 4 polymorphism of the p53 gene has been implicated in cancer risk and it has been suggested that it may have an impact on the clinical outcome of the disease. Our objective was to evaluate the association between p53 polymorphism at codon 72 and hepatocellular carcinoma. The p53 codon 72 genotype was examined in 97 biopsy samples from 67 Basque patients histologically diagnosed with hepatocellular carcinoma. Blood samples collected from 111 Basque residents were examined as a control group. The polymorphism was examined by both single strand conformation polymorphism analysis and allele specific polymerase chain reaction. Fisher's exact test was used to evaluate the data. The results showed that there were no statistically significant differences in the frequency of codon 72 polymorphism genotype between patients with liver cancer and healthy controls. We found a frequent loss of proline allele in hepatitis C virus (HCV)-positive carriers. In conclusion, the lack of a significant relationship between this polymorphism and risk of hepatocellular carcinoma suggests that it does not predispose towards hepatocarcinogenesis in this population. We suggest that the frequent loss of the proline allele in HCV-associated carcinogenesis of the liver plays some role in hepatocarcinogenesis.

Sequence structure and population data of two X-linked markers: DXS7423 and DXS8377.

DXS7423 and DXS8377 are two microsatellite markers located in the q28 band of chromosome X. We developed a protocol to amplify both markers in a single reaction, sequenced the most common alleles and studied allele frequencies in a Spanish population sample. DXS7423 allele variability was due to different numbers of (TCCA) repeats and five different alleles were found with apparent sizes between 181 and 197 bp. The probability of discrimination (PD) was 87% for female samples, and the expected probability of exclusion (PE) was 71%. DXS8377 appeared as a highly polymorphic marker with variable numbers of (CTC), (TCC) and (TTC) repeats. We found 18 alleles of different sizes (204-258 bp) and the PD and PE were 99% and 93%, respectively. These data suggest that DXS7423 and DXS8377 can be very useful markers for genetic forensic studies.