PubMed Health⌕ Search

Biomedical subjects

M V Lareu

Publications and source records attributed to M V Lareu.

54 records · Page 3Linked to original sources
PubMed1996

Failed PCR amplifications of MBP-STR alleles due to polymorphism in the primer annealing region.

The PCR-based STR system MBP-B (myelin basic protein locus B) has been reported to exhibit a high rate of mutations. Using a newly designed pair of primers we present evidence that this is due to failed amplifications caused by a polymorphism in the annealing region of the reverse primer originally designed. With the new reverse primer described here no exclusions were found (out of 59 mother/child pairs analysed) while one was detected with the old set of primers. The results obtained with both pairs of primers in a random population sample (n = 112) from North Portugal are compared. In this sample 13 individuals typed as homozygotes with the pair of primers originally described, were found to be heterozygous when the amplifications were performed with the new reverse primer. By sequence analysis, a substitution in the reverse primer binding sequence originally described was determined. This substitution is located upstream from the repetition site and consists of G-->A transition. This variation reaches polymorphic frequency and is responsible for the relatively frequent null alleles due to failed amplifications when the previously designed primers are used.

Alleles↗
PubMed1995

Report on the second EDNAP collaborative STR exercise. European DNA Profiling Group.

The European DNA Profiling Group (EDNAP) has previously carried out collaborative exercises to determine which STR systems will produce results that can be reproduced by different laboratories. The first EDNAP exercise involving STR systems focused on different types of loci: a simple locus with six common alleles (HUMTH01) and a complex locus with > 35 alleles (ACTBP2). Generally the simpler STR system was found to be readily amenable for use across a wide range of different technologies, whereas a more complex locus presented difficulties. The second EDNAP STR exercise was intended to take the process of investigation a stage further. Some laboratories are developing automation, coupled with fluorescent methods of detection and multiplex applications, whereas others use manual methods involving visual detection techniques such as silver staining. The purpose of this exercise was to determine whether loci amenable to multiplexing with automation (as a quadruplex reaction) could also be successfully used with manual methods, either by multiplexing in duplex reactions or alternatively by using just a single pair of PCR primers.

Alleles↗
PubMed1995

The use of the STRs HUMTH01, HUMVWA31/A, HUMF13A1, HUMFES/FPS, HUMLPL in forensic application: validation studies and population data for Galicia (NW Spain).

The 5 tetranucleotide short tandem repeats, HUMTH01, HUMVWA31/A, HUMF13A1, HUMFES/FPS and HUMLPL were studied using different electrophoretic methods and PCR amplification conditions in order to optimize the typing conditions. A genetic population study in the population of Galicia was carried out and the allele and genotype frequencies are given. Compliance with the Hardy-Weinberg equilibrium was tested using different statistical parameters, with clear advantages resulting in favor of using the exact test (Guo-Thompson method) instead of conventional chi-square methods. Some statistical parameters of forensic interest (PD, CE, h) were also calculated. There were no mutations found in a total of 73 paternal meioses and 101 maternal meioses. Abnormal electrophoretic mobility was found in the AT-rich STR HUMF13A1 under non-denaturing conditions and, therefore, the use of denaturing conditions is absolutely necessary. No "stutter" bands were found, although double peaks in the HUMFES/FPS system were observed in some samples. The advantage of using automated sequencers with fluorescent technology is also reported.

Base Sequence↗
PubMed1994

Investigation of the STR locus HUMTH01 using PCR and two electrophoresis formats: UK and Galician Caucasian population surveys and usefulness in paternity investigations.

Two hundred unrelated Caucasians from the UK and 210 from Galicia (NW Spain) have been genotyped for the HUMTH01 locus using polymerase chain reaction (PCR) amplification followed by high sieving agarose electrophoresis (UK samples) and polyacrylamide electrophoresis (Galician samples). Allele and genotype frequencies obtained from both populations were in close agreement to those seen by other workers and chi 2 tests of the two populations showed that both were in Hardy-Weinberg equilibrium. The potential usefulness of HUMTH01 in paternity investigations was analysed by constructing, within each population, false family trios, each with a non-father, in order to estimate the actual exclusion rate. The observed rate of exclusion was in close agreement with the expected rate for both populations. Examination of the mother-child pairs in the false families showed a common allele in every case and no evidence of mutation or non-Mendelian inheritance was observed. The HUMTH01 locus shows an informative polymorphism and the production and analysis of population databases is easily achieved. The use of PCR followed by electrophoresis in either gel format appears to provide a quick and straightforward method for investigating the HUMTH01 locus.

Adult↗
PubMed1994

Double- and single-strand conformation polymorphism analysis of point mutations and short tandem repeats.

Single point mutations in small DNA fragments and single unit differences in simple repetitive DNA can be detected as double-strand conformation polymorphisms using polyacrylamide gel electrophoresis, with and without sodium dodecyl sulfate, even at temperatures as low as 3 degrees C. Changes in a single base are distinguished by means of the analysis of the heteroduplexes, and changes in more than two bases can be distinguished in both homoduplexes and heteroduplexes. Polymerase chain reaction (PCR) conditions can be designed not only to amplify homoduplexes, heteroduplexes and single-strand DNA at the same time, but also to focus the analysis on either single-strand conformation polymorphism (SSCP) or double-strand conformation polymorphism (DSCP). DSCP seems to be advantageous in typing DNA polymorphisms or mutations in loci with few variants, but, because it is necessary to have a simple pattern of all possible combinations of the alleles, it is not as advantageous in typing systems with many variants.

Base Sequence↗
PubMed1994

Report of the European DNA profiling group (EDNAP)--towards standardisation of short tandem repeat (STR) loci.

This paper describes a collaborative exercise intended to demonstrate whether uniformity of DNA profiling results could be achieved between European laboratories using short tandem repeat (STR) loci. Two different STRs were chosen--HUMTH01 and the AT-rich HUMACTBP2 (SE33). The former locus has only five common alleles, whereas the latter is complex and has at least 30 alleles. Laboratories were asked to test seven blood stains and to report the results to the coordinating laboratory. The exercise demonstrated that the simple STR systems such as HUMTH01 are more amenable to adoption as standard loci than complex AT-rich systems.

Alleles↗
PubMed1993

The distribution of HLA DQA1 and D1S80 (pMCT118) alleles and genotypes in the populations of Galicia and central Portugal.

Two South-West European populations (Galicia and Central Portugal) have been studied for the HLA DQA1 and D1S80 systems. The allele and genotype frequencies found have been compared with other previously published data. The distribution of the observed genotypes is in Hardy-Weinberg equilibrium for both systems. In the D1S80 system, no significant differences were found between both populations, although in the HLA DQA1 system the allele DQA1*0301 is twice as frequent in the Galician population. Other populations that have been compared showed a certain degree of divergence for the HLA DQA1 system. The combined chance of exclusion for both systems is 0.84 in Galicia and 0.85 in Central Portugal, and the combined power of discrimination is 0.993 in the 2 populations studied.

Alleles↗
PubMed1992

Detection of polymorphisms of human DNA after polymerase chain reaction by miniaturized SDS-PAGE.

PCR followed by SDS-PAGE in miniaturized non-denaturing gels permits in some cases the identification of single base pair substitutions in small DNA fragments and therefore, the study of human DNA polymorphisms. The usefulness of the system in forensic science is investigated by typing the HLA-DQA1 locus and the VNTR recognized with the probe pMCT118 (locus D1S80) and it shows to be advantageous over previously published methods for typing the MCT118 system, whereas in HLA-DQA1 typing for forensic casework, both dot-blot with ASO probes and this method could be complementary.

Base Sequence↗
PubMed1992

Genetic markers in alcoholic liver cirrhosis.

11 genetic markers were typed in 157 individuals suffering from alcoholic cirrhosis, and compared with a random sample of healthy individuals. No significant differences were found for transferrin, specific group component, orosomucoid, esterase D, phosphogluconate dehydrogenase and adenylate kinase. Strong associations between alcoholic cirrhosis and alpha-1-antitrypsin PI*Z allele, haptoglobin HP*1 allele and acid phosphatase ACP AC phenotype were observed. The biological significance of these associations and their relationships with the development of alcoholic cirrhosis are also discussed.

Adult↗
PubMed1991

Electrophoretic human leukocyte antigen HLA-DQA1 DNA typing after polymerase chain reaction amplification.

An electrophoretic method (sodium dodecyl sulfate-polyacrylamide gel electrophoresis) is described which permits the identification of human leukocyte antigen HLA-DQA1 types and subtypes without using allele-specific oligonucleotide probes and dot-blot methodology. The procedure can be used in miniaturized gels in combination with automated electrophoretic systems. The PhastSystem is particularly recommended since temperature control is essential. HLA-DQA1*01 and DQA1*0301 can be distinguished in homoduplexes and DQA1*01 subtypes, DQA1*0201 and DQA1*0401 in heteroduplexes (in only 5 h including DNA extraction and PCR amplification). Additional variations to those recognized using commercially available dot-blot methods can be provided since this procedure permits the identification of single base-pair substitutions. In addition, this method is faster and less expensive than commercial methods.

Base Sequence↗
PubMedDate not supplied

New method to measure minisatellite variant repeat variation in population genetic studies.

The classical analysis of minisatellite variant repeat (MVR) variation using modular structures is limited by the lack of knowledge of the mutational process involved in the evolution of most of the minisatellites. In this study a new method to measure MVR variation and to calculate genetic distances using MVR codes is proposed. The method is based on the statistical similarity of MVR patterns and considers the complete variability of the minisatellite, enabling meaningful comparisons of closely related populations. As an example, the method has been applied to analyze variation in MSY1 (DYF155S1) in five sets of data from European and North African populations.

Genetic Markers↗
PubMedDate not supplied

mtDNA analysis of the Galician population: a genetic edge of European variation.

Analysis of mitochondrial DNA (mtDNA) variation has become a useful tool for human population studies. We analysed the first hypervariable region of mitochondrial DNA control region (position 16024-16383) in 92 unrelated individuals from Galicia (Spain), a relatively isolated European population at the westernmost continental edge. Fifty different sequences defined by 56 variable positions were found. The frequency of the reference sequence reaches in Galicians its maximum value in Europe. Moreover, several genetic indexes confirm the low variability of our sample in comparison to data from 11 European and Middle Eastern populations. A parsimony tree of the sequences reveals a high simplicity of the tree, with few and small well defined clusters. These results place Galicians on the genetic edge of the European variation, bringing together all the traits of a cul-de-sac population with a striking similarity to the Basque population. The present results are fully compatible with a population expansion model in Europe during the Upper Paleolithic age. The genetic evidence revealed by the analysis of mtDNA shows the Galician population at the edge of a demographic expansion towards Europe from the Middle East.

Base Sequence↗
PubMedDate not supplied

160Thr mutation in the rhodopsin gene associated with retinitis pigmentosa.

Mutations in the rhodopsin gene were studied in 23 unrelated Spanish patients with sporadic retinitis pigmentosa (RP). A codon 160 Thr C-->A transition was found in 4 of the 23 patients vs. none of the 159 controls (p < 0.001) suggesting that this mutation may be an informative marker in RP.

Exons↗