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Biomedical subjects

L E Figuera

Publications and source records attributed to L E Figuera.

At least 19 recordsLinked to original sources
PubMed2006

Y-linked haplotypes in Amerindian chromosomes from Mexican populations: genetic evidence to the dual origin of the Huichol tribe.

We studied six Y-linked short tandem repeats (Y-STRs) to describe the internal diversity of the Amerindian haplogroup Q-M3 in 129 males from eight Mexican populations. The low gene diversity in the Huichol tribe demonstrated the effects of genetic drift, attributable to geographic isolation and founder effect. The presence of two principal paternal lineages supported the historical and anthropometric records, which indicate that Huichols were formed by the fusion of two ancestral Mexican tribes. Moreover, genetic distances and close relationships of haplotypes between Huichols and Tarahumaras were in agreement with their linguistic affiliation. The high genetic diversity of the Purépechas and wide distribution of haplotypes along the constructed network-joining tree suggest that the present genetic composition was influenced by Purépecha dominance in western Mesoamerica. The Y-haplotypes shared between populations suggest that, among the Amerindian tribes studied herein, the paternal genetic pool of Nahuas could have contributed more importantly to the European-admixed population, the Mexican-Mestizos.

Chromosomes, Human, Y↗
PubMed2006

High-resolution molecular characterization of the HLA class I and class II in the Tarahumara Amerindian population.

We describe for the first time the high-resolution profiling of HLA-A, -B, -C, -DRB1, -DQB1 and -DPB1 in a culturally and geographically distinct Mexican ethnic group, the Tarahumaras. The alleles most frequently found by reference strand-mediated conformational analysis in this population were for class I: HLA-A*240201, *020101/09, *0206, *310102, *680102; HLA-B*4002, *1501, *510201, *3501/02/03, *4005, *4801; HLA-Cw*0304, *0801, *0102, *040101; and for class II: HLA-DRB1*080201, *1402, *040701; HLA-DQB1*0402, *0301, *0302/07; HLA-DPB1*0402, *0401, *020102. In addition, a novel allele, HLA-A*0257, was found. Based on comparison of presently known HLA-DRB1 and -DQB1 allele frequencies in Amerindian groups and worldwide populations, the Tarahumaras are unexpectedly more related to the geographically and linguistically distant Aymara and Terena Amerindian groups than they are to neighbouring tribes.

Ethnicity↗
PubMed2006

SNPs in human beta-defensin 1 gene (DEFB1): frequencies in a Mexican population and new PCR-RFLPs assays.

Polymerase chain reaction-restriction fragment length polymorphism assays for two single nucleotide polymorphisms in the human beta-defensin 1 gene have been validated with real-time PCR in 101 healthy individuals from western Mexico. Allele frequencies were 52.5% (692-A) and 98.5% (1836-A). These assays can be confidently used as a cheaper alternative genotyping method for these sites.

Ethnicity↗
PubMed2005

Haplotypes Eco47 III-Nsp I sites frequencies on the IDUA gene in Mexican native population.

BACKGROUND: The frequency of haplotypes of Nsp I-Eco47 III sites, at the IDUA (alpha-L iduronidase) gene, in Huichol, Tarahumara and Mestizo Mexican population is reported. METHODS: Eco47 III and Nsp I intragenic polymorphisms in IDUA gene are studied in three (Mestizo, Huichol and Tarahumara populations) Mexican groups. Data from normal Australian [Hum. Genet. 90 (1992) 327] individuals were considered for comparative analyses. RESULTS: The genotypes for IDUA Eco47 III and Nsp I sites in Mexicans were in agreement with Hardy-Weinberg equilibrium. Allele frequency distributions for individual sites differed (P < 0.05) except at site B1 in the Huichol group. Haplotype Eco47 III-Nsp I frequency distributions were different in the three Mexican normal groups, and it was also observed when to compared with the normal Australians. CONCLUSIONS: This characteristic makes the two IDUA polymorphic sites useful for identification purposes, and these polymorphisms could be included in a PCR based battery of DNA markers.

Adult↗
PubMed2005

A non-sense mutation in the corneodesmosin gene in a Mexican family with hypotrichosis simplex of the scalp.

BACKGROUND: Hypotrichosis simplex of the scalp (HSS; MIM 146520) is a rare autosomal dominant form of non-syndromic alopecia that affects men and women equally. Up to now, only a small number of families with HSS have been reported. The affected individuals experience a diffuse progressing hair loss from childhood to adulthood that is confined to the scalp. Recently, HSS has been mapped to the short arm of chromosome 6 (6p21.3), allowing mutations in the corneodesmosin gene (CDSN) to be identified as the cause of the disorder. To date, two stop mutations have been found in three unrelated families with HSS of different ethnic origin. OBJECTIVES: To describe the first HSS-family with Latin American (Mexican) background comprising 6 generations and to identify a mutation in the CDSN gene. PATIENTS/METHODS: The patients were examined by a clinician and blood samples were taken. After DNA extraction, sequencing analysis of the CDSN gene and restriction enzyme analysis with PsuI were performed. RESULTS: By direct sequencing of the two exons of the CDSN gene, a nonsense mutation was identified in the index patient in exon 2, resulting in a premature stop codon (Y239X). The mutation co-segregates perfectly in the family with the disease and was not found in 300 control chromosomes using a restriction enzyme analysis with PsuI. CONCLUSIONS: A nonsense mutation was identified in the first family with HSS of Latin American ethnical background. Our data provide molecular genetic evidence for a 3rd stop mutation in exon 2 of the CDSN gene being responsible for HSS. All to date known nonsense mutations responsible 3 for HSS are clustered in a region of 40 amino acids which is in accordance with a dominant negative effect conferred by aggregates of truncated CDSN proteins.

Adolescent↗
PubMed2002

Inherited hypertrichoses.

Hypertrichosis is a rare condition characterized by excessive growth of hair (terminal, vellus or lanugo) in areas of the body that are not predominantly androgen dependent, and it is independent of age, race or sex. It can be congenital, late-onset, generalized, localized, inherited or acquired. More than 50 different OMIM entries related to hypertrichosis exist, few of them with a localized gene locus or with a candidate gene. The review of generalized hypertrichoses from a historical point of view, including a review of their clinical and genetic features, shows heterogeneity with at least nine different entities. A short analysis of other forms of hypertrichosis is presented.

Genetic Diseases, Inborn↗
PubMed2002

Guadalajara camptodactyly type III: a new probably autosomal dominant syndrome.

A Mexican family is presented with the main clinical features of camptodactyly, a distinctive facial appearance because of ocular hypertelorism, telecanthus, symblepharon and spinal defects. Other clinical manifestations included: multiple nevi, simplified ears, retrognathia, congenital shortness of the sternocleidomastoid muscle, thin hands and feet, a small penis and mild mental retardation. Radiographic studies revealed spina bifida occulta at cervical and dorso-lumbar levels, increased bone trabeculae, cortical thickening and delayed bone age. The presence of five affected members through four generations suggests autosomal dominant inheritance although no male-to-male transmission was documented. The authors propose this as a new entity, and have designated it Guadalajara camptodactyly type III.

Abnormalities, Multiple↗
PubMed2000

Nine independent F9 mutations in the Mexican hemophilia B population: nonrandom recurrences of point mutation events in the human germline.

The factor IX gene (F9) is a valuable model for studying germ-line mutations. Nine mutations were detected in nine Mexican patients with hemophilia B by direct sequencing using genomic amplification with transcript sequencing (GAWTS): six single base changes, one micro-deletion, and two large deletions. Germline origins of mutations were found in three of six families with sporadic cases. Curiously, the four independent single base substitutions which were not at CpG dinucleotides occurred at only two different nucleotide positions (17,678 and 17,747) one transition and one transversion at each. The two remaining substitutions were identical changes at a CpG dinucleotide, but were determined to be independent by germline origin analysis. A statistical analysis suggests that the independent recurrence of mutations at these locations may reflect an unusual aspect of F9 mutagenesis in the Mexican population. These data raise the possibility of population-specific differences in human germline mutations.

Factor IX↗
PubMed2000

A 500-kb region on chromosome 16p13.1 contains the pseudoxanthoma elasticum locus: high-resolution mapping and genomic structure.

We have recently mapped the genetic defect underlying pseudoxanthoma elasticum (PXE), an inherited disorder characterized by progressive calcification of elastic fibers in skin, eye, and cardiovascular system, to chromosome 16p 13.1. Here we report further data on the fine-mapping and genomic structure of this locus. Haplotype analysis of informative PXE families narrowed the locus to an interval of less than 500 kb located between markers D16B9621 and D16S764. Three overlapping YAC clones were found to cover this region through YAC-STS content mapping. An overlapping BAC contig was then constructed to cover this interval and the surrounding region. About 80% of this chromosomal region has been fully sequenced using the BAC shotgun technique. Gene content and sequence analysis predicted four genes (MRP1, MRP6, PM5, and a novel transcript) and two pseudogenes (ARA and PKDI) within this interval. By screening a somatic cell hybrid panel we were able to precision-map the breakpoint of Cy185 and the starting point of a chromosomal duplication within 20 kb of BAC A962B4. The present data further refine the localization of PXE, provide additional physical cloning resources, and will aid in the eventual identification of the genetic defect causing PXE.

Adult↗
PubMed2000

Mutations of the gene encoding the transmembrane transporter protein ABC-C6 cause pseudoxanthoma elasticum.

We recently published the precise chromosomal localization on chromosome 16p13.1 of the genetic defect underlying pseudoxanthoma elasticum (PXE), an inherited disorder characterized by progressive calcification of elastic fibers in skin, eye, and the cardiovascular system. Here we report the identification of mutations in the gene encoding the transmembrane transporter protein, ABC-C6 (also known as MRP-6), one of the four genes located in the region of linkage, as cause of the disease. Sequence analysis in four independent consanguineous families from Switzerland, Mexico, and South Africa and in one non-consanguineous family from the United States demonstrated several different mis-sense mutations to cosegregate with the disease phenotype. These findings are consistent with the conclusion that PXE is a recessive disorder that displays allelic heterogeneity, which may explain the considerable phenotypic variance characteristic of the disorder.

ATP-Binding Cassette Transporters↗
PubMed2000

Virtual molecular medicine in developing countries: the Mexican initiative.

The limited resources of developing countries are forcing them to search for different options to keep up with the accelerating pace of research into genetic medicine. In Mexico, one such option is the Mexican Network of Molecular Biomedicine (MNMB). With the Internet as a means of communication and a source of information, the MNMB aims to provide a program based on cooperation, high-quality service and patient care.

Cost-Benefit Analysis↗
PubMed2000

[Detection of Mycobacterium tuberculosis by polymerase chain reaction in a selected population in northwestern Mexico].

This study compares the detection of Mycobacterium tuberculosis through bacilloscopy (Ziehl-Neelsen stain), growth in Lowenstein-Jensen medium, and polymerase chain reaction (PCR) carried out with DNA taken directly from various types of samples. A total of 252 samples were analyzed (114 sputum, 96 urine, 15 cerebrospinal fluid, and 27 of other types) from 160 patients with any form of suspected tuberculosis who came to the Clinical Pathology Laboratory of the Specialties Hospital of the Western National Medical Center of the Mexican Social Security Institute. In all cases Ziehl-Neelsen stains were done, as were also cultures with Lowenstein-Jensen medium and PCR amplification of a segment of 285 base pairs specific to the M. tuberculosis complex. Of the 252 samples, with the culture, 18 were positive for nontuberculous mycobacteria. Of the 234 others, 12 (5.1%) were positive with the PCR and the culture, 174 (74.4%) negative in both tests, 47 (20.1%) positive with the PCR and negative with the culture, and 1 (0.4%) negative with the PCR and positive with the culture. Using the culture as the reference test, the PCR provided a sensitivity of 92.3%, a specificity of 78.7%, a positive predictive value of 20.3%, and a negative predictive value of 99.4%. The PCR detection limit with DNA taken from culture was 10 fg, equivalent to four or five mycobacteria. Also in comparison with the culture, the PCR correctly identified the totality of the mycobacteria of the M. tuberculosis complex. Taking the culture as the reference test, when analyzing just the sputum samples, the direct PCR provided a sensitivity of 90.9%, a specificity of 89.5%, a positive predictive value of 52.6%, and a negative predictive value of 98.7%. The PCR is a sensitive and specific technique for detecting the M. tuberculosis complex in both positive and negative bacilloscopy samples. A controlled PCR procedure makes it possible to establish or to exclude the diagnosis of tuberculosis in a time that is reduced from more than three weeks to just 24 to 48 hours. This is particularly useful when an early diagnosis is needed to establish a patient's prognosis or in organ transplant cases.

Bacteriological Techniques↗
PubMed2000

Genetic variation among four Mexican populations (Huichol, Purepecha, Tarahumara, and Mestizo) revealed by two VNTRs and four STRs.

Allele distributions of two polymorphisms with variable number of tandem repeats (VNTR), D1S80 and APOB, and four polymorphisms with short tandem repeats (STR), VWA, TH01, CSF1PO, and HPRTB, were analyzed in three Mexican ethnic groups: Huichol, Purepecha, and Tarahumara. Genotype distribution was in agreement with Hardy-Weinberg expectations for each locus and ethnic group. Heterozygosity (H), power of discrimination, and probability of exclusion were estimated. The three groups presented some distinctive genetic features: (1) a diminished genetic diversity (H = 66.8% to 73.4%) and mean number of alleles by locus (5.8 to 6.3) in comparison with Mexican mestizos (H = 78.3%, 10.5 alleles/locus), and (2) uneven allele distributions as evidenced by "distinctive alleles" with high frequencies, especially in the Tarahumara and the Huichol. Genetic relatedness analysis included data from a previously typed mestizo population, the largest and most widely distributed population in Mexico. Allele distribution differentiation was observed among all four groups, except between mestizo and Purepecha (p > 0.05), which was interpreted as indicating a larger Spanish component in the Purepecha as a result of gene flow effects. Although intrapopulation inbreeding (FIS) was not significant, heterozygote deficiency in the total population (FIT) and divergence among populations (FST) were significant (p < 0.05). Genetic distances displayed a closer relationship among mestizos, Purepechas, and Huichols in relation to Tarahumaras. Correlation between the observed genetic features and the geographic isolation level points to genetic drift as the main cause of differentiation among these Mexican populations.

Consanguinity↗
PubMed1999

Allele frequency distributions of six Amp-FLPS (D1S80, APO-B, VWA, TH01, CSF1PO and HPRTB) in a Mexican population.

Six amplified fragment length polymorphisms or Amp-FLPs, two VNTRs (D1S80 and APO-B) and four STRs (VWA, TH01, CSF1PO and HPRTB), were typed in a Mexican population of the Jalisco state by means of non-denaturing polyacrylamide gel electrophoresis (native PAGE) in standard gel units and silver staining. Genotype distribution was in agreement with Hardy-Weinberg expectations (HWE) for all six markers. Heterozygosity ranged from 70.6 to 83.5%, the cumulated chance of exclusion (CE) and power of discrimination (PD) were 99.4 and 99.99%, respectively. STRs and D1S80 allele frequency distributions (AFD) were similar (P > 0.05) to U.S. Hispanics, but different to U.S. Caucasians and African-Americans. APO-B exhibited similarities with White Brazilians, Spaniards, but differences (P < 0.05) with Amerindian and Black Brazilians.

Alleles↗
PubMed1998

Histone H4 acetylation analyses in patients with polysomy X: implications for the mechanism of X inactivation.

In humans, it is thought that the X-inactivation phenomenon occurs no matter how many X chromosomes are present, and that only one of them remains active. Nevertheless, individuals who have an abnormal number of X chromosomes show a wide spectrum of abnormalities, which increase with the number of X chromosomes present in a given individual. It has been shown that the inactive X chromosome in female mammals is distinguished by a lack of histone H4 acetylation, and that this could be used as an accessible marker for distinguishing between Xi and Xa in spreads of metaphase chromosomes. We studied three X-polysomic patients for the presence of active chromatin by analysis of histone H4 acetylation on unfixed metaphase spreads. Using antisera to H4 acetylated at lysines 16, 8 and 5, respectively, we observed frequencies different from those expected from cells with only one underacetylated X chromosome. In particular, when antiserum to H4 acetylated at lysine 16 was used about 90% of the cells showed acetylation of all X chromosomes. This suggests a possible disturbance in the deacetylation process, probably due to the presence of multiple Xs.

Acetylation↗
PubMed1997

Congenital hypertrichosis, osteochondrodysplasia, and cardiomegaly: further delineation of a new genetic syndrome.

The hypertrichosis and osteochondrodysplasia syndrome is a rare entity with clinical findings including macrosomia at birth cardiomegaly. Autosomal recessive inheritance is presumed based on the report of two affected sibs born to healthy parents. Here we report on four new patients with their follow-up data, as well as on one of the four cases from the original report. Comparison of all eight cases indicates that they share 50% of clinical and radiological changes. This report contributes to the further delineation of this newly recognized syndrome.

Abnormalities, Multiple↗
PubMed1997

Mucopolysaccharidoses type II: enzymatic activity and quantitative and qualitative studies of urinary glycosaminoglycans in five patients.

Five patients presenting Hunter's syndrome were biochemically studied. Quantification of urinary glycosaminoglycans (GAGs), electrophoretic characterization and correlation with enzymatic activity in leucocytes were carried out. In all cases, urinary GAGs/creatinine ratio was increased. Electrophoresis revealed the presence of heparan sulfate (HS) and dermatan sulfate (DS) in four cases (80%), but in the remaining patient, only DS was present. In all patients, deficient enzymatic activity was demonstrated. These results show evidences of biochemical differences in this syndrome.

Child↗