Publications by authors named "Lisbeth Borjas-Fajardo"

7 Publications

  • Page 1 of 1

[C677T polymorphism of the methylentetrahydrofolate reductase gene as risk factor in women with recurrent abortion].

Invest Clin 2009 Sep;50(3):327-33

Unidad de Genética Médica, Facultad de Medicina, Universidad del Zulia, Maracaibo, Venezuela.

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.
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September 2009

[Indirect prenatal molecular diagnostic of haemophilia A and B].

Invest Clin 2008 Sep;49(3):289-97

Unidad de Genética Médica, Facultad de Medicina, Universidad del Zulia, Maracaibo, Venezuela.

Haemophilia A (HA) and B (HB) are the most common inherited bleeding diseases. HA and HB are X-linked recessive disorders caused by mutation in the factor VIII gene which maps to Xq28 and factor IX located at Xq27, respectively; resulting in absence or deficiency of these proteins. Several mutations have been reported as responsible for the disturbance of these genes; therefore, the use of direct molecular techniques to analyze the carrier status of women and their affected fetuses in not easy to perform. Thus, gene linked polymorphisms analysis is the most convenient molecular test since it is independent from the nature of the mutation, allowing the identification of the mutant X chromosome by following its segregation along the pedigree. The main objective of this research was to perform the molecular diagnosis of HA or HB carrier status in pregnant women and male fetuses affected or not, who were referred to the Medical Genetic Unit of the University of Zulia (UGM-LUZ), Maracaibo, Venezuela. Molecular analysis for HA and HB was performed in 32 DNA samples from 8 pregnant women, 8 fetuses, 8 affected and 8 healthy males. Using the Polymerase Chain Reaction (PCR), a 142 bp (bases pairs) fragment, which corresponds to intron 18 of the Factor VIII gene, was amplified. This fragment has a restriction polymorphism for the enzyme Bcl I. Additionally, a Duplex PCR was performed for the STRs (short tandem repeat) of introns 13 and 22 of the same gene. On the other hand, Hinf I, Xmn I y Taq I polymorphism in the factor IX gene were also amplified, so, we were able to build the haplotypes for each one of the key members in the families affected. The latter, allowed us to identify, in five of the eight cases, the mutant X chromosome responsible of HA and HB, thus, prenatal diagnosis was possible with the following results: three healthy males fetuses, two affected males fetuses with HA and three females fetuses.
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September 2008

[Molecular analysis of microdeletions of the Y chromosome in Venezuelan males with idiopathic infertility].

Invest Clin 2006 Dec;47(4):395-403

Instituto de Investigaciones Clínicas Dr. Am6rico Negrette, Facultad de Medicina, Universidad del Zulia, Maracaibo, Venezuela.

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.
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December 2006

[Frequency of delta F508 mutation in Venezuelan patients with cystic fibrosis].

Invest Clin 2004 Jun;45(2):121-30

Unidad de Genética Médica, Facultad de Medicina, Universidad del Zulia, Maracaibo, Venezuela.

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%).
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June 2004

[Analysis of Bsm I polymorphism of the vitamin D receptor (VDR) gene in Venezuelan female patients living in the state of Zulia with osteoporosis].

Invest Clin 2003 Dec;44(4):275-82

Laboratorio de Genética Molecular, Unidad de Genética Médica, Facultad de Medicina, Universidad del Zulia, Maracaibo, Venezuela.

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.
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December 2003

Behavior of loci D1S1656 and D12S391 in a sample from Maracaibo, Venezuela.

Am J Hum Biol 2003 Jan-Feb;15(1):68-71

Laboratorio de Genética Molecular Unidad de Genética Médica Universidad del Zulia, Maracaibo, Venezuela.

Two recently reported short tandem repeat polymorphisms characterized by PCR, D1S1656 and D12S391, were investigated in a sample from Maracaibo, an admixed population of Venezuela, in order to evaluate their application in forensic and population genetics studies. The unbiased heterozygosities were 0.9011 and 0.8444 for locus D1S1656 and D12S391, respectively. The joint discrimination power and joint probability of exclusion were 0.99972 and 0.93287. When allele frequencies of locus D1S1656 from Maracaibo were compared with eight other populations, our group clustered with the European or European-derived samples, mainly from Spain. In the comparison of locus D12S391 with 16 populations, Maracaibo clustered with 3 Asian samples. The high heterozygosity and discrimination power make these two loci important candidates to be considered for STR packages for forensic and population genetic purposes.
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http://dx.doi.org/10.1002/ajhb.10118DOI Listing
February 2003

[Clonal chromosomal anomalies in colorectal tumors].

Invest Clin 2002 Dec;43(4):263-70

Unidad de Genética Médica, Facultad de Medicina, Universidad del Zulia, Maracaibo, Venezuela.

Colorectal tumors constitute a reason of frequent consultation in gastroenterology services in the world. They constitute the second cause of mortality in the world and the fourth cause of mortality for cancer in Venezuela. It usually begins as a polyp that becomes malignant due to a mutation at the level of the genetic code that controls the growth and the repair of cells. The present work reports the clonal chromosomal abnormalities observed in 15 samples from benign tumors as well as malignant colorectal tumors and to relate these findings. There were clonal chromosomal anomalies in 11/15 (73.33%), 4 corresponded to carcinomas and 7 to adenomatous polyps. In 7/11 (63.6%) there were anomalies of the monosomy type in the chromosomes 8 and 22, other anomalies corresponded to trisomy of the chromosomes 11 and 18, and a single case with a structural anomaly that corresponded to a del(17p). The chromosomal anomalies in adenomatous polyposis have been related with the beginning of malignant disease and, in the case of carcinomas, it has been related with progression of the illness toward metastasis and death. The use of this tool could be used as a prognostic factor for patients with non familial adenomatous polyposis.
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December 2002