The left gastric vein as an alternative to portal reconstruction in orthotopic liver transplantation.
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Child, Preschool↗
Biomedical subjects
A Amorim
Publications and source records attributed to A Amorim.
Mitochondrial portrait of the Cabo Verde archipelago: the Senegambian outpost of Atlantic slave trade.
In order to study the matrilineal genetic composition in Cabo Verde (Republic of Cape Verde), an archipelago that used to serve as a Portuguese entrepôt of the Atlantic slave trade, we have analysed a total of 292 mtDNAs sampled from the seven inhabited islands for the hypervariable segment I (HVS-I) and some characteristic RFLPs of the coding regions. The different settlement history of the northwestern group of the islands is well reflected in the mtDNA pool. The total Cabo Verde sample clearly displays the characteristic mitochondrial features of the Atlantic fringe of western Africa and testifies to almost no mitochondrial input from the Portuguese colonizers.
Amino Acid Sequence↗
Bantu and European Y-lineages in Sub-Saharan Africa.
Ancient diversity in Sub-Saharan Africa is known to have been re-modulated to a large extent by Bantu migrations in the sub-Sahel region, in two southwards waves of advance through both the west and east coasts. Haplotype matching performed for Y-STR haplotypes in several sub-Saharan populations, both inside and outside the migration path, allowed the confirmation of a putative founder haplotype, and its one-step neighbours, of Bantu origin, and detected an increasing drift towards the south, with a stronger reduction of diversity along the western coast. A mixed frequency distribution for the Bantu haplotype core in South Africa, relative to the western and eastern pools, seems to provide evidence for the intermingling between both Bantu waves in that region. The proportion of male lineages considered as predating the Bantu expansion reached 8.8% in Mozambique. Further influence on sub-Saharan diversity may have occurred during the colonial period; in Mozambique, the European genetic impact in the male component was estimated to be around 5.9%, in significant contrast with the female counterpart where no European lineages were detected.
Africa South of the Sahara↗
Haplotype study of microsatellites flanking the t(15;17) breakpoint in acute promyelocytic leukemia patients from North Portugal.
A higher frequency of acute promyelocytic leukemia (APL) has been noted in countries of Southern Europe and among 'Latino' patients of the United States with acute myeloid leukemia (AML). In order to discover whether there is any genetic predisposition to the disease, we analyzed microsatellites flanking PML and RARalpha genes in 29 t(15;17) APL patients from North Portugal and compared them with a control group of 123 healthy individuals. Fluorescent PCR products were analyzed using an automated capillary electrophoresis system and allele and haplotype frequencies of the two populations were determined. No significant differences were found, suggesting the same genetic origin of patients and healthy individuals. As suggested by the four microsatellites screened, MSI (microsatellite instability) does not explain the increased incidence of t(15;17) APL in this Portuguese population. These results intend to be a new approach to the study of APL, reflecting the particularity of the disease.
Chromosomes, Human, Pair 15↗
The GSTM1 and GSTT1 genetic polymorphisms and susceptibility to acute lymphoblastic leukemia in children from north Portugal.
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Child↗
Haplotype analysis and phylogeny of ornithine transcarbamylase polymorphisms.
Ornithine transcarbamylase (OT2, EC 2.1.3.3) deficiency, the most common inborn error of urea cycle, is caused by a vast number of point mutations, deletions and insertions in the respective gene. Furthermore, 12 single nucleotide polymorphisms (NSPs) have been described in the OTC gene, four of them causing an amino acid change. We have studied the frequency of these markers in two populations: Portuguese and Mozambican. No significant differences were observed between populations, except for Lys --> Arg in codon 46. Allelic associations between polymorphisms were used to define haplotypic patterns. The three common haplotypes (H1, H2 and H3) show a combined frequency of 95% in Portugal and 87% in Mozambique. One haplotype was found only in Portugal and three are only present in Mozambique, resulting in a higher haplotype diversity. The combined information from the SNPs and the DXS1068 (CA)n repeat was used to outline OTC haplotype phylogeny, which, in conjunction with the population data, allowed us to sketch possible evolutionary pathways although some haplotypes could have arisen by either repeated mutation or recombination.
Alleles↗
Specific haplotypes of the RET proto-oncogene are over-represented in patients with sporadic papillary thyroid carcinoma.
BACKGROUND: Papillary thyroid carcinoma (PTC), which may be sporadic (95%) or familial (5%), has a prevalence adjusted for age in the general population of 1:100 000. Somatic rearrangements of the RET proto-oncogene are present in up to 66% of sporadic tumours, while they are rarely found in familial cases. PURPOSE: In order to determine if some variants of this gene, or a combination of them, might predispose to PTC, we looked for an association of RET haplotype(s) in PTC cases and in controls from four countries matched for sex, age, and population. METHODS: Four single nucleotide polymorphisms (SNPs) across the RET coding sequence were typed and haplotype frequencies were estimated. Genotype and haplotype distributions were compared among these cases and controls. RESULTS: Ten haplotypes were observed, the seven most frequent of which have been previously described in sporadic Hirschsprung patients and controls. The single locus analyses suggested association of exon 2 and exon 13 SNPs with sporadic PTC. The haplotype analysis showed over-representation of one haplotype in French and Italian sporadic PTC, whereas a different haplotype was significantly under-represented in French familial PTC. CONCLUSIONS: Our data suggest that some variants of RET and some specific haplotypes may act as low penetrance alleles in the predisposition to PTC.
Age Factors↗
STR data for the AmpFlSTR profiler plus loci from Macau (China).
Allele frequencies for the nine STRs included in the AmpFlSTR profiler plus kit (D3S1358, VWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317 and D7S820) were estimated from a sample of 87 unrelated individuals living in the region of Macau, a territory located in the southeastern coast of China.
Alleles↗
STR data (CD4, CSF1PO, F13A01, FES/FPS, MBPB, TH01, TPOX) from North Portugal.
Allele frequencies for seven STRs (CD4, CSF1PO, F13A01, FES/FPS, MBPB, TH01, TPOX) were estimated from samples (sized between 300 and 940) of unrelated individuals born in North Portugal.
Alleles↗
Y-chromosome STR haplotypes in the Madeira archipelago population.
Allele and haplotype frequencies of seven Y-chromosome STR loci were determined from a sample of 95 and 16 unrelated males from Madeira and Porto Santo Islands, respectively.
Genetic Variation↗
STR data (AmpFlSTR Profiler Plus and GenePrint CTTv) from Mozambique.
Allele frequencies for twelve STRs included in the AmpFlSTR Profiler Plus kit (D3S1358, VWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317 and D7S820) and GenePrint CTTv kit (VWA, TH01, TPO and CSF1PO) were estimated from a sample of 110 unrelated individuals from Mozambique.
Black People↗
Online reference database of European Y-chromosomal short tandem repeat (STR) haplotypes.
The reference database of highly informative Y-chromosomal short tandem repeat (STR) haplotypes (YHRD), available online at http://ystr.charite.de, represents the largest collection of male-specific genetic profiles currently available for European populations. By September 2000, YHRD contained 4688 9-locus (so-called "minimal") haplotypes, 40% of which have been extended further to include two additional loci. Establishment of YHRD has been facilitated by the joint efforts of 31 forensic and anthropological institutions. All contributing laboratories have agreed to standardize their Y-STR haplotyping protocols and to participate in a quality assurance exercise prior to the inclusion of any data. In view of its collaborative character, and in order to put YHRD to its intended use, viz. the support of forensic caseworkers in their routine decision-making process, the database has been made publicly available via the Internet in February 2000. Online searches for complete or partial Y-STR haplotypes from evidentiary or non-probative material can be performed on a non-commercial basis, and yield observed haplotype counts as well as extrapolated population frequency estimates. In addition, the YHRD website provides information about the quality control test, genotyping protocols, haplotype formats and informativity, population genetic analysis, literature references, and a list of contact addresses of the contributing laboratories.
Databases, Factual↗
STR data from S. Tomé e Príncipe (Gulf of Guinea, West Africa).
Allele frequencies for eight STRs (CD4, FES/FPS, MBPB, TH01, TP53, TPO, F13A1, VWA) were estimated from samples (sized between 279 and 328) of unrelated individuals born in S. Tomé e Príncipe (Gulf of Guinea, West Africa).
Africa↗
STR data (AmpFlSTR profiler plus) from north Portugal.
Allele frequencies for the nine STRs included in the AmpFlSTR Profiler Plus kit (D3S1358, VWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317 and D7S820) were estimated from a sample of 365-427 unrelated individuals born in north Portugal.
Alleles↗
VWA STR genotyping: further inconsistencies between Perkin-Elmer and Promega kits.
We report a simultaneous study of the VWA STR locus by the Perkin-Elmer Profiler Plus kit and the Promega GenePrint CTTv kit in a population sample from North Portugal and in 418 meiosis from family material and paternity cases. PCR amplification and genotyping were performed according to the manufacturer's instructions using ABI 377 or ABI 310 automatic sequencers. Biological kinship in family material and paternity cases was validated by the use of the STR loci D3S1358, D5S818, D7S820, D8S1179, D13S317, D18S51, D21S11, FGA, CSF1PO, TH01 and TPOX. Out of 434 unrelated individuals we found 4 inconsistencies between the genotypes obtained using each kit. No exclusions were found in the meiotic analyses. In all cases, these inconsistencies were due to an annealing failure of the Perkin-Elmer forward primer resulting in false homozygotes. Sequencing analysis revealed an A-to-T substitution at position 1631 (GenBank sequence M25858), 52 bases upstream of the first TCTA motif of the repeat region. An estimate of the null allele frequency (s) in this study is thus obtainable from the expression s = 4/(2 x 434) = 0.46%. The relatively high frequency of these discrepancies in our population demonstrates the need for caution when comparing genotype or gene frequency estimates made from amplicons produced by different primers, when evaluating apparent exclusions in paternity testing and when searching for a match between individual genetic profiles in forensic databases. Our findings are also compared with those previously reported.
Alleles↗
Patterns of haplotype diversity within the serpin gene cluster at 14q32.1: insights into the natural history of the alpha1-antitrypsin polymorphism.
The levels of haplotype diversity associated with different alpha1-antitrypsin (PI) alleles were assessed by the analysis of three microsatellites located within or close to corticosteroid-binding globulin (CBG), alpha1-antitrypsin [PI-(TG)n] and protein C inhibitor [PCI-(TG)n] loci in three populations with different historic backgrounds: Portugal, the Basque Country and São Tomé Príncipe (Gulf of Guinea). Unlike the more distant PCI-(TG)n repeat, allelic variation at PI-(TG)n reflected distinct phases of mutational recovery of microsatellite diversity around different founder alleles and showed a considerable differentiation between alpha1-antitrypsin protein variants. In accordance with population history, the Basque sample presented overall reduced levels of microsatellite variation. The African sample, although presenting the highest PCI-(TG)n diversity, showed a lineage-specific reduction in PI-(TG)n heterozygosity within the oldest M1Ala213 variant that could have been caused by (1) selection at a closely linked locus or (2) biases in the microsatellite mutation process leading to a stable equilibrium distribution. Age estimates of alpha1-antitrypsin variants based on microsatellite variation suggest that the Z deficiency allele appeared 107-135 generations ago and could have been spread in Neolithic times. The S mutation has an older 279- to 470-generation age, indicating that its high frequencies in Iberia did not result from a recent bottleneck and that PI*S could have originated in this region. M2 and M3 types had lower age estimates than would be expected from their wide geographical distributions, suggesting that their dispersion in Europe might have been preceded by important bottlenecks.
Alleles↗
Evidence for population sub-structuring in São Tomé e Príncipe as inferred from Y-chromosome STR analysis.
Seven Y-chromosome STR loci, DYS19, DYS389I, DYS389II, DYS390, DYS391, DYS392 and DYS393 have been analysed in population samples of Angolares, Forros and Tongas, three ethnic groups from the African archipelago of São Tomé e Príncipe (Gulf of Guinea). Complete typings were obtained for 103 chromosomes, which belonged to 79 different haplotypes. The mean heterozygosity per locus in the overall São Tomean sample was 0.566, with the highest value found among Forros and the lowest among Angolares. Angolares also showed the lowest level of haplotype diversity. On average, the mean pairwise difference between two random haplotypes from Angolares, Forros and Tongas was 4.69, 6.74 and 6.23 repeats, respectively. The genetic distances were found to be statistically significant between Angolares and Forros or Tongas. In accordance, AMOVA revealed that the percentage of variation attributable to differences among groups was only significant when we distinguished between Angolares and non-Angolares. Globally, these results indicate that, with respect to the pool of male lineages of São Tomé e Príncipe, some genetic sub-structuring does exist, basically determined by the Angolares ethnic group.
Emigration and Immigration↗
Molecular characteristics of four human Y-specific microsatellites (DYS434, DYD437, DYS438, DYS439) for poulation and forensic studies.
In this work we present results on DYS434, DYS437, DYS438 and DYS439 loci studied in three population samples from North Portugal (N: 69), Macao (N: 59) and Mozambique (N: 64). Gene and haplotype diversity values are presented and compared. Gene diversity values ranged from 0.0290 to 0.0620 for DYS434; 0.0615 to 0.5959 for DYS437; 0.4906 to 0.6424 for DYS438; 0.5873 to 0.7038 for DYS439. The highest average gene diversity was found in Macao and the lowest in Mozambique. Haplotype diversity in North Portugal, Macao and Mozambique was calculated to be 0.925, 0.928 and 0.787, respectively. Allele and haplotype frequency distributions for all markers were compared between the three populations. At the haplotype level all the differences between pairs of samples were significant. Sequencing analysis was performed for all alleles found in the four loci. Identical flanking sequences were observed with most of the alleles differing only by the repeat number. However, two variations were found in allele 10 of DYS438: one in a Macao sample presenting a TTTTA before the last TTTTC repetition and one in a Portuguese sample showing a base substitution (A/C) at position 7 downstream from the tandem repeat. A base substitution (C/T) at position 3 upstream from the repeat motif was also found in allele 14 of DYS437 in a sample from Mozambique.
Alleles↗