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• Compact SNaPshot-based ancestry SNP test called PIMA developed with 26 autosomal SNPs, 1 X-SNP and amelogenin. • 22 American-continent study populations characterized for 25 PIMA SNPs and 27 SNPs of 34plex forensic ancestry SNaPshot test. • PIMA very efficient at detecting and apportioning co-ancestry in admixed populations in America, including 4-way admixture in São Paulo sample. • Evaluations of admixed samples typed in common with PIMA+34plex vs a 314-SNP genomics set shows equivalent power to detect American co-ancestry. • Comparisons of PIMA+34plex and Y/mtDNA patterns in admixed Venezuelans highlights need for powerful autosomal SNPs added to uni-parental data. We describe an ancestry-informative autosomal SNP multiplex designed to be a small-scale, flexible panel that can complement uniparental markers in assessing the American variability (i.e. pre-Colombian) found in contemporary indigenous American populations. This study centered on choosing SNPs with the specific characteristics of: 1) extreme allele frequency differences between indigenous Americans and the African, European and East Asian population groups that contribute to present-day population variation in the Americas; 2) high informativeness-for-assignment I n values; and 3) well-spaced genomic distribution and chromosomal separation from existing small-scale forensic ancestry marker sets. The resulting capillary electrophoresis SNaPshot single base extension test was named: PIMA (Population Informative Multiplex for the Americas), comprising 26 autosomal SNPs, a single X-chromosome SNP plus the amelogenin sex marker adapted for SNaPshot. PIMA complements the established 34plex forensic ancestry panel to provide a powerful and simple tool for the analysis of American populations, including those with admixed histories, commonly encountered in America. Comparing the results obtained with the combined marker panels of PIMA and 34plex to SNP data from a much larger ancestry panel allowed us to gauge their relative efficiency. PIMA+34plex gives equivalent power to the 314-SNP 'LACE' genomic ancestry control panel, while requiring a much smaller genotyping effort. The ancestry profiles and genetic structure of 22 populations spread across the American continent were estimated using PIMA+34plex data, and those estimates were contrasted with information provided by uniparental markers (mtDNA and Y-chromosome loci) for a small set of admixed individuals from Venezuela. Our results indicate that an American genetic component is efficiently detected in contemporary American populations using a small set of ancestry informative SNPs, and these co-ancestry estimates are consistent with the known history and demography of the Americas. The small scale and high population differentiation power of PIMA, particularly when combined with 34plex, provides a practical and powerful tool for genetic studies of American populations as well as forensic DNA analyses. [ABSTRACT FROM AUTHOR]

Abstract: The control region of the human mitochondrial DNA (mtDNA) is highly polymorphic due to a rapid rate of evolution. The hypervariable segments HVI and HVII of the mitochondrial control region (D-loop) are the most variable part of human mitochondrial DNA. Blood samples from 50 unrelated individuals born from Maracaibo City (Venezuela) were obtained from routine paternity. Polymerase chain reaction amplification products were purified and fluorescent-based capillary electrophoresis sequencing method, the sequences were analysed and it is compared DNA sequences with the rCRS. The dominant haplogroups corresponded to Amerindians followed by African. The nucleotide positions most common for HVII was 263G (100%), 315.1C (100%), 73G (94%), and 309.1C (66%) and for HVI 16223T (74%), 16362C (56%), 16319A (40%) and 16111T (34%). [Copyright &y& Elsevier]

Allele frequencies for nine autosomal STRs loci were obtained from individuals from a sample of unrelated individuals born in Venezuela. [ABSTRACT FROM AUTHOR]

Prostate Cancer (CAP), is a complex disease with a multifactorial origin. It is characterized by heterogenous patterns of growth of neoplasic tissue, varying widely in its progression, age of beginning and therapy response. It is considered as the second most common cause of death by cancer in men and, it has been estimated, that one of five, suffers of CAP through the course of his life. The genetic etiology of neoplasic transformation of normal prostate cells is still not known; nevertheless, investigations in epidemiology have demonstrated a strong genetic component in its development, suggesting so much a pattern of mendelian inheritance as the presence of loci of susceptibility throughout the human genome. It has been described a cromosomic location related to the CAP in locus 1q24-25, denominated HPC1, where the gene RNASEL is located, and the seggregation of its alleles has been associated with the development of CAP in numerous familiar groups. The RNASEL gene codifies for a ribonuclease protein that degrades vi-ral and cellular ARN and takes part in the apoptosis. A decrease of the enzymatic activity up to three times in carriers of the G1385A polymorphism of this gene has been reported, and the same has been associated frequently with the development of CAP. Using a variant of the Polymerase Chain Reaction, Allele specific amplification, this investigation had as objective to determine the association between variant G1385A and CAP, in a sample of 103 masculine individuals with and without CAP, pertaining to the population of Maracaibo, Venezuela. An association between these variants and CAP could not be demonstrated.

The pathogenesis of recurrent spontaneous abortion is multifactorial, presumably involving the interaction of several genetic and environmental factors. The methylenetetrahydrofolate reductase (MTHFR) gene C677T polymorphism has been implicated as risk factor for recurrent spontaneous abortion (RA). The main objective of this research was to investigate the association between the C677T polymorphism of the MTHFR gene as a genetic risk factor for idiopathic RA. Molecular analysis was performed in 80 DNA samples from 30 patients with RA and among 50 healthy control subjects. Using the Polymerase Chain Reaction (PCR), a 198 bp (bases pairs) fragment, was digested with the restriction enzyme Hinf1, which can recognize the C > T substitution responsible for the polymorphism. 677T MTHFR allele frequencies for group with RA and the control group were 35% and 33%, respectively and 677C MTHFR allele frequencies were 65% and 67%, respectively. There was no significant difference in allele frequency between these two groups. The data presented in this study fail to support the relationship between MTHFR C677T polymorphism and risk in women with RA.

Mutations in the K-ras oncogene are common in colo-rectal cancer, which affect the biological behaviour and may influence the susceptibility to therapy in these tumors. The objective of this work was to identify the types of K-ras mutations observed in referred patients with colo-rectal cancer and to relate them to their degree of histological differentiation and clinical stage. Histopathological and clinical data were obtained from medical records. DNA was obtained from both, fresh tissue and tumor tissue embedded in paraffin. The K-ras gene was amplified through the polymerase chain reaction (PCR) and the amplified fragments were digested with restriction enzymes. We found mutations in codons 12 and 13 of the K-ras oncogene in 23.33% of patients. Of these, 28.57% were located at codon 12, 57.14% were at codon 13 and 14.29% at both codons. They were more frequent in tumors located in the left hemicolon and, according to their histological type, were more frequent in well differentiated adenocarcinomas (58.70%) and in mucinous (28.57%). The identified mutations were more frequent in advanced stages (C2) of Dukes' classification. The molecular analysis of the K-ras oncogene made mutations evident, which could be useful in the diagnosis and prognosis of colorectal tumors. The frequency of mutations found in this work is similar to some of those reported worldwide; however, they differ in the more frequent type of mutation, which, in our study, was located at codon 13 in more than 50% of the cases.

The distribution of allele frequencies and haplotypes for 12 STRs loci, (DYS19, DYS389I/II, DYS390, DYS391, DYS392, DYS393, DYS385a/b, DYS437, DYS438 and DYS439) on the Y-chromosome from two Venezuelan populations were determined in 173 DNA samples of unrelated males living in Caracas (62) and Maracaibo (111). Some parameters of forensic importance were calculated. AMOVA and genetic distances between these populations were estimated. The results confirmed Y-STR genotypes as useful markers for forensic genetics analysis.

Today infertility is a major health problem affecting about 10-20% of couples. A male factor is assumed to be responsible in about 50% of the infertile couples. The origin of reduced testicular sperm function is unknown in about 60-70% of cases. There are several causes of male infertility such as varicocele, spermatic duct obstruction, and endocrine disorders. Micro-deletions in the Yq are known to represent the pathogenic mechanisms for infertile males. Three different non-overlapping regions designated as AZFa, AZFb, and AZFc are located in interval 5-6 of Yq, and are associated with impaired spermatogenesis in humans. To determine the prevalence of Y chromosomal microdeletions in Venezuelan males with idiopathic infertility, chromosomal, seminal, histological and molecular analyses were carried out in 29 Venezuelan males with idiopathic azoospermia or oligoospermia. Y-microdeletions analyses were performed using a multiplex polymerase chain reaction (PCR)-based technique with 22 sequences-tagged-sites (STSs). One of 29 patients (3.4%) had Yq microdeletions on AZFc. The frequency of AZF microdeletions in Venezuelan patients was similar to other populations with different ethnical or geographical origin.

Allele frequencies for 15 short tandem repeats (STRs) autosomal loci (D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, vWA, TPOX, D18S51, D5S818 and FGA, included in the AmpFLSTR Identifiler, Applied Biosystems) were studied in the city of Maracaibo, Venezuela and were compared with other published Latin-American populations for the same loci. Population and forensic parameters were estimated.

Cystic Fibrosis (CF) is the most common and severe autosomal recessive disease in Caucasian populations, with an incidence of 1 in 2500 live births. It is characterized by a generalized disturbance in exocrine glands and it is caused by over one thousand mutations at the cystic fibrosis conductance regulator gene (CFTR) mapped at 7q31. AF508 is the most frequent mutation worldwide and it consists in a deletion of the codon that encodes fenilalanine at the 508 protein's position. The aim of this study was to determine the frequency of the delta F508 mutation in Venezuelan patients with CF using the Polymerase Chain Reaction (PCR). We studied thirty patients of twenty eight families who were diagnosed with CF based on their clinical features and sweat chloride level > 60 mEq/l in two determinations. Detection of the mutation was performed from the amplification of a 98 pair of bases (pb) CF gene segment which contains the codon that encodes fenilalanine in the 508 position by PCR. This PCR product is absent in those who have the mutation. The delta F508 allelic frequency was 26.79%, distributed in six homozygous and seven compound heterozygote delta F508/X. The reminder mutations (no delta F508) represent 73.21%. The delta F508 frequency in our sample is less than the reported in European countries. On the other hand, a delta F508 frequency highly heterogeneous has been observed in Latin-American countries. This variation results from mixed populations with a different genetic background influenced by external migration and CF molecular alterations, which exists in the analyzed populations. In this study, the delta F508 mutation comes mainly from grandparents (79.41%) who were born in Mediterranean countries and Colombia, while the no delta F508 mutations come from grandparents who were born in Venezuela (79.27%) and Colombia (17.07%).

Among genes implied on the osteoporosis genetics, the most studied gene worldwide is the receptor gene of D vitamin (VDR), through the characterization of Bsm I polymorphism. The main objective of this research was to analyze the Bsm I polymorphism of the VDR gene in a sample of 133 postmenopausal women distributed in three groups: 54 with osteoporosis, 24 with osteopenia and 55 normal controls for the disease. 28 of the women with osteoporosis presented the BB genotype, which is related in other countries to bone mineral density decrease, 20 had the Bb genotype, and 6 the bb genotype. Of the control group only 11 women presented the BB genotype, 36 showed the heterozygote genotype and 8 the bb genotype. The frequencies of the B and b alleles in the analyzed population were 0.6 and 0.4 respectively. The BB genotype was found in 52% of the group with osteoporosis, and in 20% of the control group, these findings are statistically significant, which suggest an association between the BB genotype and osteoporosis.