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L Gusmão

Publications and source records attributed to L Gusmão.

At least 19 recordsLinked to original sources
PubMed2007

Dissecting the genetic history of São Tomé e Príncipe: a new window from Y-chromosome biallelic markers.

Twenty biallelic Y chromosome markers were analyzed in Angolares, Forros and Tongas, three population groups from the African archipelago of São Tomé e Príncipe. While most male lineages belonged to sub-Saharan haplogroups, the component of European origin added up 23.9% in the archipelago. This contrasts with the reported absence of European mtDNA lineages, and the combined findings testify to a strong sex-biased admixture process during the long-lasting colonial period in São Tomé e Príncipe. Furthermore, the male mediated European component was clearly found to be out of proportion to the small demographic impact of the Portuguese on the islands, reflecting high variance in the reproductive success of the individuals that contributed to its peopling. The male portion of European ancestry was 33.3% in Forros, 27.3% in Tongas and approximately two-fold less, 14.5%, in Angolares. The Angolares also showed the lowest haplogroup diversity and the most reduced number of different haplogroups. The current results reinforce our previous evidence pointing to remarkable restrictions in gene flow between Angolares and other São Tomean inhabitants, in agreement with their considerable isolation and confinement to the south-eastern tip of São Tomé until recently.

Africa↗
PubMed2006

H-RAS 81 polymorphism is significantly associated with aneuploidy in follicular tumors of the thyroid.

Follicular thyroid tumors are often aneuploid. It was advanced that chromosomal instability is closely associated to RAS mutations, but such association remains unproven. H-RAS can be alternatively spliced in two different proteins, p21 and p19, the former being the active protein. In order to investigate the relationship between RAS mutational status and ploidy in thyroid tumors, we analysed RAS genes in a series of 99 follicular lesions (14 nodular goiters, 70 follicular adenomas and 15 follicular carcinomas), eight thyroid carcinoma cell lines and a control group of 102 blood donors, correlating the presence of RAS mutations with the ploidy of the tumors and evaluating the two spliced forms of H-RAS. Overall, 20% of the follicular tumors harbored RAS mutations and 62% of the patients with follicular tumors (and 51% of blood donors) harbored the H-RAS 81T --> C polymorphism. The presence of RAS mutations was not associated with aneuploidy. The H-RAS polymorphism did not seem to confer a higher propensity for neoplastic transformation as it was also found in hyperplastic lesions, but was strongly associated with aneuploidy (P<0.0001). The presence of the H-RAS 81T --> C polymorphism was associated with significantly higher amounts of total H-RAS mRNA expression, higher amounts of p21 isoform and a higher fraction of neoplastic cells in S phase. Our results suggest that the H-RAS 81T --> C polymorphism may induce aneuploidy through overexpression of the active p21 isoform of H-RAS.

Adenocarcinoma, Follicular↗
PubMed2006

DNA Commission of the International Society of Forensic Genetics (ISFG): an update of the recommendations on the use of Y-STRs in forensic analysis.

The DNA Commission of the International Society of Forensic Genetics (ISFG) regularly publishes guidelines and recommendations concerning the application of DNA polymorphisms to the problems of human identification. A previous recommendation published in 2001 has already addressed Y-chromosome polymorphisms, with particular emphasis on short tandem repeats (STRs). Since then, the use of Y-STRs has become very popular, and a numerous new loci have been introduced. The current recommendations address important aspects to clarify problems regarding the nomenclature, the definition of loci and alleles, population genetics and reporting methods.

Alleles↗
PubMed2006

DNA Commission of the International Society of Forensic Genetics (ISFG): an update of the recommendations on the use of Y-STRs in forensic analysis.

The DNA Commission of the International Society of Forensic Genetics (ISFG) regularly publishes guidelines and recommendations concerning the application of DNA polymorphisms to the problems of human identification. A previous recommendation published in 2001 has already addressed Y-chromosome polymorphisms, with particular emphasis on short tandem repeats (STRs). Since then, the use of Y-STRs has become very popular, and numerous new loci have been introduced. The current recommendations address important aspects to clarify problems regarding the nomenclature, the definition of loci and alleles, population genetics and reporting methods

Alleles↗
PubMed2005

Population data on 15 autosomal STRs in a sample from East Timor.

Allele frequencies for the fifteen STRs included in the AmpF/STR Identifiler (CSF1PO, D2S1338, D3S1358, D5S818, D7S820, D8S1179, D13S317, D16S539, D18S51, D19S433, D21S11, FGA, TH01, TPO and VWA) were estimated from a sample of 186 unrelated individuals from East Timor. No deviations from Hardy-Weinberg equilibrium were observed (only after applying the Bonferroni correction in the cases of D2S1338, TPO and D5S818). Genetic parameters of forensic interest were calculated and comparison with geographically nearby populations was performed.

DNA Fingerprinting↗
PubMed2005

A case of double alleles at three Y-STR loci: forensic implications.

In a genetic study of unrelated donors from Bahia (Brazil), one sample contained a 16 Y-STR haplotype with double peaks at three loci: DYS389 II, DYS437 and DYS439. The son of the subject had the same haplotype as found in the father. This profile was compared with a similar case found in a paternity case investigation in Madrid (Spain) and a match was found for the full 16 Y-STR haplotype. Because these three loci are located within the AZFa segment, these results are in accordance with duplication of the AZFa region that includes also other Y-STRs currently used in forensic investigation, for example DYS389I and DYS438. This case attracts our attention in the forensic interpretation of Y-haplotype profiles, because multiple alleles at various loci do not indicate forcibly that the sample under analysis is a mixture.

Brazil↗
PubMed2005

Mutation rates at Y chromosome specific microsatellites.

A collaborative work was carried out by the Spanish and Portuguese ISFG Working Group (GEP-ISFG) to estimate Y-STR mutation rates. Seventeen Y chromosome STR loci (DYS19, DYS385, DYS389I and II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438, DYS439, DYS460, DYS461, DYS635 [GATA C4], GATA H4, and GATA A10) were analyzed in a sample of 3,026 father/son pairs. Among 27,029 allele transfers, 54 mutations were observed, with an overall mutation rate across the 17 loci of 1.998 x 10(-3) (95% CI, 1.501 x 10(-3) to 2.606 x 10(-3)). With just one exception, all of the mutations were single-step, and they were observed only once per gametogenesis. Repeat gains were more frequent than losses, longer alleles were found to be more mutable, and the mutation rate seemed to increase with the father's age. Hum Mutat 26(6), 520-528, 2005. (c) 2005 Wiley-Liss, Inc.

Age Factors↗
PubMed2005

Mitochondrial DNA haplotyping revealed the presence of mixed up benign and neoplastic tissue sections from two individuals on the same prostatic biopsy slide.

DNA typing was requested to investigate a presumptive cancer diagnosis error by confirming whether benign and cancerous prostatic tissue in the same presurgical haematoxylin and eosin stained slide belonged to the same person. After independent histological re-examination of the slide by a pathologist, manual slide dissection was used to guarantee independent and high recovery DNA isolation from each tissue section, avoiding carryover and background contamination. Nuclear DNA quantification performed by real time polymerase chain reaction (PCR) revealed the absence of human DNA for short tandem repeat (STR) typing. Mitochondrial DNA was only obtained by performing PCR of very short fragments ( approximately 100 bp), indicating high DNA degradation. Different low frequency hypervariable region I haplotypes were obtained from each tissue section (normal tissue section haplotype: 16224C, 16234T, 16311C, 16356C; cancer tissue section haplotype: 16256T, 16270T, 16293G). Only the normal tissue section haplotype matched that obtained from the patient's blood sample, indicating that the cancer tissue section originated from an unknown patient. These results supported the hypothesis of sample mix up during block processing or slide preparation by a carryover mechanism. Mitochondrial genetic typing is recommended to exclude the possibility of carryover artefacts when low DNA content and high degradation compromise conventional STR typing.

Artifacts↗
PubMed2004

17 STR data (AmpF/STR Identifiler and Powerplex 16 System) from Cabinda (Angola).

Allele frequencies for seventeen STRs included in the AmpF/STR Identifiler (CSF1PO, D2S1338, D3S1358, D5S818, D7S820, D8S1179, D13S317, D16S539, D18S51, D19S433, D21S11, FGA, TH01, TPOX, and VWA) and Powerplex 16 System (CSF1PO, D3S1358, D5S818, D7S820, D8S1179, D13S317, D16S539, D18S51, D21S11, FGA, Penta D, Penta E, TH01, TPOX, and VWA) were estimated from a sample of 110 unrelated individuals from Cabinda, Angola. Comparative analyses between our population data and other African databases, namely Promega's African-Americans, AB Applied Biosystems African-Americans and five other population samples gathered from the literature are also presented.

Angola↗
PubMed2004

Pattern of mtDNA variation in three populations from São Tomé e Príncipe.

We have analysed the matrilineal genetic composition of three self-reported ethnic groups from São Tomé e Príncipe (Gulf of Guinea), an African archipelago whose settlement begun in the late fifteenth century. Sequence data from the hypervariable segments I (HVS-I) and II (HVS-II) were obtained for 30 Angolares, 35 Forros and 38 Tongas. The repertory of mtDNA lineages in São Tomé e Príncipe denoted a fully African maternal pool, primarily arisen from a Central/Southwestern substratum. The absence of any lineages of putative European descent means that the European impact at the mitochondrial pool was virtually nil. Angolares showed a clear reduction of mtDNA diversity and a slight genetic differentiation relative to Tongas or Forros, whereas the latter two groups did not present any signs of genetic boundaries between each other. The data obtained here reinforce the depiction of genetic substructuring in São Tomé e Príncipe previously derived from Y-chromosome STRs. In addition, the crossing of mtDNA and Y-STR information led to the inference that the female mediated gene flow within the archipelago was less restricted than the male, a pattern that could be framed in the cultural traditions and socio-historical interactions among the groups.

Africa↗
PubMed2002

Extending STR markers in Y chromosome haplotypes.

Two multiplex reactions were developed to amplify 16 Y-STRs (DYS19, DYS385, DYS389 I and II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438, DYS439, GATA A7.1, GATA A7.2, GATA A10, GATA C4, GATA H4). Here we extend previous population studies done in a sample from northern Portugal for the GATA A7.1, GATA A7.2, GATA C4 and GATA H4 loci. A total of 199 different haplotypes identified by the 16 Y-STR markers were observed in a sample of 208 male individuals, of which 190 were unique and 9 were found twice. The overall haplotype diversity was 0.9996. The haplotype diversity of the Y-STR set composed of the 8 new markers is higher than the Y-STR core set included in the Y-STR haplotype reference database. Sequence structure of new alleles for GATA C4 and GATA H4 is reported. The usefulness of the inclusion of this new set of Y-STRs in forensic casework was also assessed. The increase in haplotype diversity with the addition of any new Y-STR marker to the 8 Y-STR core set is dependent not only on the gene diversity (positively) but also (negatively) on the degree of gametic association between the markers and the haplotypes previously defined. For instance, in our sample the addition of the DYS437, DYS438 and GATA A7.2 to a 13-locus set increased haplotype diversity only by 0.0001.

Base Sequence↗
PubMed2002

Genetic diversity of Y-specific STRs in chimpanzees (Pan troglodytes).

Using the primers described for humans, sequences for 11 Y-specific microsatellites (DYS434, DYS435, DYS436, DYS437, DYS438, DYS439, GATA A10, A7.1, A7.2, C4, and H4 [Gusmão et al., in press]), previously described in 10 male chimpanzees (Pan troglodytes), were confirmed in nine additional male chimpanzees. Sequences for nine additional microsatellites (DYS19, DYS385I and II, DYS389I and II, DYS390, DYS391, DYS392, and DYS393) were determined in all 19 male chimpanzees; homology to human Y-Short Tandem Repeat (STRs) was confirmed by sequencing. Good amplification results were not obtained for DYS19 and DYS385I/II. Two amplicons were obtained for DYS389I/II, but in contrast to humans, the larger fragment was not Y-specific. Moreover, no polymorphism was observed for DYS434, DYS435, or GATA A10. Consequently, these eight STRs were eliminated from further analyses, and haplotype and allele frequencies were estimated for the remaining 12 STRs. A high haplotype diversity value was found (1.000 +/- 0.017), demonstrating the usefulness and informative power of these Y-STRs for future studies on chimpanzee population genetics.

Amino Acid Sequence↗
PubMed2002

Forensic evaluation and population data on the new Y-STRs DYS434, DYS437, DYS438, DYS439 and GATA A10.

The Y-specific STR loci DYS19, DYS385, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS434, DYS437, DYS438, DYS439 and GATA A10 were studied in a northern Portuguese population. Haplotype and allele frequencies of these 14 Y-chromosome STRs were estimated. In a sample of 212 individuals it was possible to define 196 different haplotypes of which 182 were found only once, 12 were found in 2 samples and the 2 most frequent haplotypes were shared by only 3 individuals. The observed haplotype diversity value was 0.9992. The usefulness of the inclusion of each of these new markers for forensic purposes is discussed by comparing expected and observed increases in haplotype diversity. When combining the new markers (DYS434, DYS437, DYS438, DYS439 and GATA A10) with the classical set (DYS19, DYS385, DYS389I, DYS389II, DYS390, DYS391, DYS392 and DYS393) a 0.68% increase in haplotype diversity was obtained and the number of different haplotypes rose from 157 to 196. When DYS434 was not considered the haplotype diversity was not affected.

Forensic Medicine↗
PubMed2002

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↗
PubMed2001

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↗