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Tacrolimus (TAC) is an immunosuppressant drug that prevents organ rejection after transplantation. This drug is transported from cells via P-glycoprotein (ABCB1) and is a metabolic substrate for cytochrome P450 (CYP) 3A enzymes, particularly CYP3A4 and CYP3A5. Several single-nucleotide polymorphisms (SNPs) have been identified in the genes encoding CYP3A4 , CYP3A5 , and ABCB1 , including CYP3A4-392A/G (rs2740574), CYP3A5 6986A/G (rs776746), and ABCB1 3435C/T (rs1045642). This study aims to evaluate the association among CYP3A4-392A/G, CYP3A5-6986A/G, and ABCB1-3435C/T polymorphisms and TAC, serum concentration, and biochemical parameters that may affect TAC pharmacokinetics in Mexican kidney transplant (KT) patients., Methods: Forty-six kidney transplant recipients (KTR) receiving immunosuppressive treatment with TAC in different combinations were included. CYP3A4, CYP3A5, and ABCB1 gene polymorphisms were genotyped using qPCR TaqMan. Serum TAC concentration (as measured) and intervening variables were assessed. Logistic regression analyses were performed at baseline and after one month to assess the extent of the association between the polymorphisms, intervening variables, and TAC concentration., Results: The GG genotype of CYP3A5-6986 A/G polymorphism is associated with TAC pharmacokinetic variability OR 4.35 (95%CI: 1.13-21.9; p = 0.0458) at one month of evolution; in multivariate logistic regression, CYP3A5-6986GG genotype OR 9.32 (95%CI: 1.54-93.08; p = 0.028) and the use of medications or drugs that increase serum TAC concentration OR 9.52 (95%CI: 1.79-88.23; p = 0.018) were strongly associated with TAC pharmacokinetic variability., Conclusion: The findings of this study of the Mexican population showed that CYP3A5-6986 A/G GG genotype is associated with a four-fold increase in the likelihood of encountering a TAC concentration of more than 15 ng/dL. The co-occurrence of the CYP3A5-6986GG genotype and the use of drugs that increase TAC concentration correlates with a nine-fold increased risk of experiencing a TAC at a level above 15 ng/mL. Therefore, these patients have an increased susceptibility to TAC-associated toxicity.

Systemic lupus erythematosus (SLE) is a multisystem disease considered a prototype of the main autoimmune disease and presents serious complications, such as lupus nephritis (LN), which generates a significant impact on morbidity and mortality. The SPP1 gene encodes the osteopontin (OPN) protein, which plays a crucial role in the regulation of inflammation and immunity. The variants rs1126616 and rs9138 of this gene have been associated with the inflammatory response. The study aims to analyze the association of the rs1126616 and rs9138 variants of the SPP1 gene in SLE Mexican-Mestizo patients without LN (SLE-LN). In this cross-sectional study, a total of 171 genomic DNA samples from SLE patients were clinically confirmed, of which 111 were SLE without LN, 60 were SLE with LN, and 100 healthy individuals were included as reference group. The rs1126616 variant was genotyped using PCR-RFLPs, and the rs9138 variant was genotyped using qPCR TaqMan. The TT genotype, the recessive model [OR 2.76 (95% CI 1.31-5.82), p = 0.011], and the T allele [OR 2.0 (95% CI 1.26-3.16), p = 0.003] of the rs1126616 variant are risk factors for SLE with LN. By contrast, the rs9138 variant did not show statistically significant differences among SLE patients stratified by LN. In our study of SLE Mexican-Mestizo patients with and without NL, demographic and clinical characteristics do not differ from other SLE populations, and the TT genotype of the rs1126616 variant of the SPP1 gene confers a risk factor for the presentation of LN. Otherwise, the rs9138 variant did not show association with NL.

Breast cancer (BCa) is the most common type of cancer affecting women worldwide. Some histological subtypes of benign breast disease (BBD) are considered risk factors for developing BCa. Single nucleotide polymorphisms (SNPs) in the genes encoding apolipoproteins A-I ( APOA1 ) and B ( APOB ) have been associated with BCa in Tunisian, Chinese, and Taiwanese populations. The objective of this pilot study is to evaluate the possible contribution of APOA1 and APOB polymorphisms to BCa and BBD in the Mexican population. We analyzed the association of 4 SNPs in genes encoding apolipoproteins: rs670 and rs5069 in the APOA1 gene, and rs693 and rs1042031 in the APOB gene, by performing PCR-RFLP with DNA extracted from the biopsy tissue of Mexican women with BCa or BBD and whole blood samples obtained from the general population (GP). Our results showed an association between the CT + TT genotypes of the SNP rs5069 and BBD ( p = 0.03201). In the A-T haplotype, the frequency of the SNPs rs670 and rs5069 differed significantly between the BBD group and the GP and BCa groups ( p = 0.004111; p = 0.01303). In conclusion, the SNP rs5069 is associated with BBD but not with BCa in the Mexican population.

MicroRNAs are considered as potential biomarkers, agents, or therapeutic targets; few studies have addressed the expression of miRNAs in treatment-naïve patients infected with HIV-1. The aim of this study was to assess plasma relative circulating miRNA expression profiles in treatment-naïve Mexican patients with HIV/AIDS and healthy individuals using a commercial array. A low CD4+ T cell count and high viral load were found in all patients. Decreased relative miRNA-296-5p expression was observed in patients; moreover, this was the only miRNA that showed differences between the two groups. Thus, we measured the absolute expression of miR-296-5p by qPCR, confirming the result with statistically significant differences (P < 0.05). There is evidence that miR-296-5p regulates the expression of the PIN1 gene, which encodes the peptidylprolyl Cis/Trans isomerase NIMA-Interacting-1, that is involved in different stages of the biological cycle of HIV-1, this relationship is corroborated by bioinformatics analysis and ELISA assay was used to measure plasma levels of PIN1. The decreased expression of miR-296-5p found in naïve patients with HIV infection suggests a regulatory activity of this miRNA on virus replication, making it a potential therapeutic agent against HIV. Finally, miR-296-5p could be inhibiting the virus transcription by regulating genes different than PIN1.

MicroRNAs (miRNAs/miRs) may serve as therapeutic agents or targets in diseases in which the expression of proteins plays an important role. The aim of the present study was to compare the expression levels of specific miRNAs, as well as their correlation with markers of response to antiretroviral (ARV) therapy, in patients with human immunodeficiency virus type 1 (HIV-1) infection with and without resistance to highly active antiretroviral therapy (HAART)., Methods: miRNA assays were performed on plasma samples obtained from 20 HIV-1-positive patients. A total of ten patients were divided into two groups: HAART-responsive and HAART-resistant (n=5 per group). Commercial arrays were subsequently used to identify 84 miRNAs. A total of three differentially expressed miRNAs were selected and analyzed by quantitative PCR (qPCR). Five other patients were subsequently added to each group for a new relative expression analysis. The absolute expression level of the two miRNAs was obtained and compared using the Student's t test. Receiver operating characteristic (ROC) curves were used to identify patients with antiretroviral therapy (ART) resistance., Results: The array analysis revealed that miR-15b-5p, miR-16-5p, miR-20a-5p, miR-26a-5p, miR-126-3p and miR-150-5p were down-regulated in patients with HAART-resistance comparing with HAART-responsive. The expression levels of miR-16-5p, miR-26a-5p and miR-150-5p were confirmed using qPCR. The area under the ROC curve was 1.0 for the three miRNAs., Conclusions: The lower expression levels of miR-16-5p and miR-26a-5p in patients with HAART-resistance suggested that these may serve as potential biomarkers for the identification of HAART-responsive patients., (© 2020 The Author(s).)

Aim: The present study looked for variation in the miRNA-24 sequence, and evaluated the associations between the dihydrofolate reductase (DHFR) gene-829 C-T polymorphism and plasma DHFR concentrations with response to methotrexate (MTX) treatment in Mexican patients with rheumatoid arthritis (RA)., Methods: A total of 135 women with RA were classified as responders (disease activity score [DAS28] <3.2) or nonresponders to MTX (DAS28 > 3.2). We determined the genotype of the patients using the polymerase chain reaction-restriction fragment length polymorphism method. Plasma DHFR enzyme levels and mi-RNA24 sequences were assessed by enzyme-linked immunosorbent assay (ELISA) and Sanger sequencing, respectively. Allelic frequencies and the genotypic distribution of the polymorphism were analyzed by the chi-square test., Results: The genotype frequencies of the DHFR -829C-T polymorphism among responders were 37.0% CC, 52.1% CT, and 10.9% TT and for nonresponders were 33.9% CC, 56.4% CT, and 9.7% TT. No significant differences in genotype frequencies were found between the groups (p = 0.88). The DHFR levels relative to genotype for responders were 6.8 ± 2.7, 6.1 ± 2.7, and 6.5 ± 1.5 ng/mL for CC, CT, and TT, respectively, and for nonresponders were 6.5 ± 2.0, 6.1 ± 3.1, and 7.4 ± 1.8 ng/mL for CC, CT, and TT, respectively. No significant differences were found between the two groups. Similarly, both groups showed no sequence variations in miRNA-24 gene., Conclusion: The -829C-T polymorphism of DHFR gene was not associated with response to MTX by RA patients, and no variations were found in the miRNA-24 sequence that might modify the response to treatment or DHFR enzyme levels in a Mexican population with RA.

Aim: To investigate the relationships of polymorphisms in genes whose protein products are related in the metabolic pathway of folic acid, particularly MTRR A66G, RFC1 G80A, and MTHFR C677T and A1298C, and disease activity in Mexican patients with rheumatoid arthritis (RA) treated with methotrexate (MTX)., Materials and Methods: Sixty-eight patients with RA were included in the study who were being treated with MTX, either with or without other drugs. In addition to general data, disease activity was measured by the disease activity score 28 (DAS28). Single nucleotide polymorphisms (SNPs) genotyping was performed by allelic discrimination using real-time polymerase chain reaction., Results: Differences in genotype (homozygotic or heterozygotic for each allele), allele distributions, and phenotype were not statistically different between the RA group and control populations. We did not find any association between the studied polymorphisms and disease activity nor with the intragroup variables (e.g., clinical activity, body mass index, and single- or combined-drug treatment) or between genetic markers; we also did not find any association within the RA group or between the RA group and control populations., Conclusion: Additional studies of more polymorphisms related to this or other metabolic pathways are required to determine the influence of genetics on disease activity in RA.

Aims: Polymorphisms in the CYP2C9 and CYP2C19 genes confer potential risk for specific adverse drug reactions and therapeutic effect failure. Their frequencies differ among ethnic groups. This study was aimed to describe the distribution of CYP2C9 and CYP2C19 alleles and haplotypes in four Mestizo populations from Western Mexico and their comparison with the reported data from other ethnic groups., Methods: The CYP2C alleles (CYP2C9*2, CYP2C9*3, CYP2C19*2, and CYP2C19*3) were genotyped using polymerase chain reaction-restriction fragment length polymorphisms analyses using DNA samples from 477 healthy Mestizo individuals of Colima (n = 100), Jalisco (n = 147), Michoacán (n = 117), and Nayarit (n = 113)., Results: Frequencies ranged from 2.2-3.0% and 4.8-8.9% for CYP2C9*3 and CYP2C9*2 alleles, respectively, and 5.4-12.0% for CYP2C19*2, whereas the CYP2C19*3 allele was not found. Haplotype GACA, which harbors the loss-of-function allele CYP2C19*2, was the second most frequent (8.7%). Genetic heterogeneity between the Western Mexican populations studied here and the global population was evident (p < 0.05), except for most American populations and other Mexican Mestizo populations., Conclusion: Our findings increase the evidence for genetic variability at relevant pharmacogenetic loci and could be useful in association studies involving drugs that are substrates for CYP2C enzymes in the Western Mexican population.

Accumulative evidence suggests that alterations due to mutations or genetic polymorphisms in the TCF7L2 and CCND1 genes, which are components of the Wnt signaling pathway, contributes to carcinogenesis. The present study was designated to clarify whether common single nucleotide polymorphisms (SNPs) of the transcription factor 7- like 2 (TCF7L2) and cyclin D1 (CCND1) genes are associated with colorectal cancer risk in Mexican patients. A case-control study including 197 colorectal cancer patients and 100 healthy subjects was conducted in a Mexican population. Identification of polymorphisms was made by the polymerase chain reaction-restriction fragment length polymorphism methodology. The association was calculated by the odds ratio (OR) test. The results demonstrate that patients with the T/T genotype for the rs12255372 polymorphism of the TCF7L2 gene present an increased colorectal cancer risk (OR=2.64, P=0.0236). Also, the risk analysis for Tumor-Nodule-Metastasis (TNM) stage and tumor location showed association with this polymorphism under the over-dominant model of inheritance (OR=1.75, P=0.0440). A similar relation was observed for the genotype T/T of the rs7903146 polymorphism and the rectal location of cancer (OR=7.57, P=0.0403). For the rs603965 polymorphism of the CCND1 gene, we observed a protection effect for the colon cancer location under the dominant model (OR=0.49, P=0.0477). These results reveal a significant role of the analyzed polymorphisms in the TCF7L2 and CCND1 genes on the susceptibility or protection for developing colorectal cancer in the Mexican population.

Unlabelled: The angiotensin (Ang)-converting enzyme (ACE) insertion/deletion (I/D) polymorphism determines Ang II levels, but its relationship with lupus nephritis (LN) in different populations is controversial., Objective: To describe the allelic and genotypic distribution of the I/D polymorphism in Mexican mestizos with LN and assess an association with histological classes., Methods: We included 24 patients with systemic lupus erythematosus (SLE) without nephropathy, 41 with LN, 144 healthy subjects, and 36 with primary glomerulonephritis (GMN). Three ACE I/D polymorphism genotypes-ID, DD, and II--were detected by PCR using peripheral blood genomic DNA., Results: Frequencies for II, ID, and DD were 0.29, 0.46, and 0.25 in the SLE group; 0.17, 0.63, and 0.20 in the LN group; 0.14, 0.5, and 0.36 in the GMN group; and 0.26, 0.52, and 0.22 among healthy subjects. The I/D polymorphism distribution according to histological class was class II: 1 II, 3 ID, and 1 DD; class III: 2 II, 10 ID, and 1 DD; class IV: 2 II, 9 ID, and 2 DD; class V: 2 II, 3 ID, and 4 DD; and class VI, 1 II. The histological classes with at least three patients had ID genotype as the most frequent except for class V., Conclusion: No association was identified between I/D polymorphisms of ACE and SLE, LN, or GMN in a Mexican population.

Introduction: Prostate cancer is one of the most common malignant neoplasias in developed countries. In 2003, 6,536 new cases and 4,602 related deaths were reported in Mexico. The renin-angiotensin system has been shown to play a role in prostate cancer pathology. Two previous studies investigated the association of prostate cancer with the insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme (ACE) gene; both studies reported an association between prostate cancer and the DD genotype. The present study was aimed at searching for an association of prostate cancer and benign prostatic hyperplasia with the I/D polymorphism in the ACE gene and the A1166C polymorphism in the angiotensin type 1 receptor (AGT1R) gene and at comparing allele frequencies between both groups and the general population., Materials and Methods: DNA was extracted from 20 samples from individuals with a prostate cancer diagnosis and from 20 samples from individuals with a benign prostatic hyperplasia diagnosis. Genotyping was performed by PCR-RFLP analysis. Polymorphism frequency results obtained for the test groups were compared with the frequencies in 66 individuals from the general population, which were previously obtained at the same molecular medicine laboratory in the context of other studies., Results: The comparative analysis of the three groups revealed significant differences for allele frequencies in the two genes in patients groups (prostate cancer and benign prostatic hyperplasia) versus the general population. The D allele in the ACE gene was closely associated with a significant higher risk of developing both benign prostatic hyperplasia (odds ratio [OR]=21.87; 95% confidence interval [CI]=2.314-206.479) or prostate cancer (OR=31.66; 95% CI=0.091-1.272), and the AGT1R A1166 allele in the homozygote state was identified as a risk genotype for benign prostatic hyperplasia (OR=56.07)., Conclusions: Genotypes in ACE and AGT1R polymorphisms could be considered as genetic risk markers for benign prostatic hyperplasia or prostate cancer.

Background: Non-syndromic cleft lip with or without cleft palate (NSCLP) is a common malformation. The aetiology is multifactorial. An incidence of 1.1-1.39 per 1000 new births had been reported in Mexico. The folic acid intake in preconceptional stage has been reported to prevent malformations such as neural tube defects (NTD) and NSCLP. The C677T variant of the methylene-tetrahydrofolate reductase (MTHFR) gene is responsible of a thermolabile form, related to decrease of folate and increase homocysteine. This variant has been associated with CLP, in different populations, but results are still controversial. Our objective was to determine the allelic (AF) and genotypic frequency (GF) of the MTHFR-C677T variant in Mexican children with NSCLP., Methods: Transverse comparative study in 67 Mexican children with NSCLP and a control group with 70 unrelated Mexican individuals without NSCLP., Results: The AF in NSCLP was 39 %. There was no statistical difference between AF in the two groups (39 versus 41)., Conclusions: In this population, genotype C677T was not a major risk factor for this malformation, however, sample size, other genes implicated and genes-environment interactions must be considered.

Human papillomavirus (HPV) is considered the aetiological agent for cervical cancer. Several reports have addressed a relationship with HPV and breast cancer, as different HPVs have been identified. The purpose of this study was to detect HPV DNA in 67 breast cancer patients and 40 non-malignant disease breast tissues by means of Polymerase Chain Reaction with consensus primers. The frequency of HPV in the cases group were 4.4% (3/67) and no positive samples among the reference group were identified. From the 3 positive samples, HPV types 16, 18 and 33 were identified by restriction patterns and direct sequencing. The high diversity among detection in the related studies shows that population genomic heterogeneity plays an important role in the disease. The low frequency detected in the present study suggests that HPV does not play an important role in breast cancer.

The analysis of polymorphic markers within or closely linked to the cystic fibrosis transmembrane regulator (CFTR) gene is useful as a molecular tool for carrier detection of known and unknown mutations. To establish the association between mutations in the CFTR gene in western Mexican cystic fibrosis (CF) patients, the distribution of XV2c/KM19 haplotypes was analyzed by PCR and restriction enzyme digestion in 384 chromosomes from 74 CF patients, their unaffected parents, and normal subjects. The haplotype analysis revealed that haplotype B was present in 71.9% of CF chromosomes compared to 0% of non-CF chromosomes. The F508del and G542X mutations were strongly associated with haplotype B (96.7% and 100% of chromosomes, respectively). The haplotype distribution of the CF chromosomes carrying other CFTR mutations had a more heterogeneous background. Our results show that haplotype B is associated with CFTR mutations. Therefore, haplotype analysis is a suitable alternate strategy for screening CF patients with a heterogeneous clinical picture from populations with a high molecular heterogeneity where carrier detection programs are not available. In addition, it may be a helpful diagnostic tool for genetic counseling and carrier detection in the relatives of CF patients and in couples who are planning to have children.

Type 2 diabetes mellitus is a complex metabolic disorder resulting from the action and interaction of many genetic and environmental factors. It has been reported that polymorphisms in genes involved in the metabolism of glucose are associated with the susceptibility to develop type 2 diabetes mellitus. Although the risk of developing type 2 diabetes mellitus increases with age, as well as with obesity and hypertension, its prevalence and incidence are different among geographical regions and ethnic groups. In Mexico, a higher prevalence and incidence has been described in the south of the country, and differences between urban and rural communities have been observed. We studied 73 individuals from Santiago Jamiltepec, a small indigenous community from Oaxaca State, Mexico. This population has shown a high prevalence of type 2 diabetes mellitus, and the aim of this study was to analyze the relationship between the Pst I (insulin gene), Nsi I (insulin receptor gene) and Gly972Arg (insulin receptor substrate 1 gene) polymorphisms and type 2 diabetes mellitus, obesity and hypertension in this population. Clinical evaluation consisted of BMI and blood pressure measurements, and biochemical assays consisted of determination of fasting plasma insulin and glucose levels. PCR and restriction enzyme digestion analysis were applied to genomic DNA to identify the three polymorphisms. From statistical analysis carried out here, individually, the Pst I, Nsi I and Gly972Arg polymorphisms were not associated with the type 2 diabetes, obese or hypertensive phenotypes in this population. Nevertheless, there was an association between the Nsi I and Pst I polymorphisms and increased serum insulin levels.

The metabolic or insulin resistance syndrome, characterized by hypertension, dyslipidemia, glucose intolerance and hyperinsulinemia, may have genetic determinants. The insulin gene (INS), insulin receptor gene (INSR) and insulin receptor substrate 1 gene (IRS1) have been proposed as candidate genes. We examined eight polymorphisms in these genes in 163 individuals from Yucatan, Mexico; this population has a high prevalence of obesity, type 2 diabetes mellitus and dyslipidemia. Subjects were evaluated for body mass index (BMI) and blood pressure. Blood samples were collected to determine glucose, insulin, triglycerides and cholesterol levels, as well as for DNA isolation. Restriction fragment length polymorphisms in INS, INSR and IRS1 were identified by polymerase chain reaction and digestion with selected restriction enzymes. Among the eight polymorphisms analyzed, the PstI polymorphism in INS was significantly associated with hypertriglyceridemia and with the presence of at least one abnormality related to the metabolic syndrome (P=0.007 and 0.004, respectively). The MaeIII polymorphism in INS was associated with fasting hyperinsulinemia (P=0.045). In multilocus analyses including both INS polymorphisms, significant associations were seen with hypertriglyceridemia (P=0.006), hypercholesterolemia (P=0.031) and with presence of at least one metabolic abnormality (P=0.009). None of the polymorphisms in INSR or IRS1 was associated with any of these traits. These findings suggest that the insulin gene may be an important determinant of metabolic syndrome, and particularly of dyslipidemia, in this population.

A polymorphism at codon 72 in the p53 gen has been reported as a potential risk factor to cervical cancer (CC) because human papillomavirus (HPV) is more effective at degrading p53 Arg-72 than p53 Pro-72, making individuals homozygous for p53 Arg-72 seven times more likely to develop HPV-associated CC. As In Mexico the CC is a health public problem, we designed this study to determinate whether the p53 codon 72 polymorphism represent a risk factor to CC in our population. A case-controls study was performed. DNA was obtained from paraffin-embedded cervical fixed tissue samples. Analysis of the p53 genotype at position 72 was performed by polymerase chain reaction using specific primers and Accll digestion. Among cases with CC the proportions of the p53 genotypes at codon 72 were 0.05 to proline homozygous, 0.5 to heterozygous, and 0.45 to arginine-homozygous. In controls the proportions were 0.08, 0.62, and 0.31. X2 test showed no significant difference In the proportions. We conclude than In our population, as other worldwide countries, the homozygous for arginine at codon 72 of the p53 gene is not a risk factor to cervical cancer.

The purposes of this study were to estimate the infection frequency of Human Papilomavirus (HPV) and to identify the viral types in patients with diagnosis of uterine cervical cancer (UCC) and High Grade Squamous Intraepitelial lesions (HGSILs), and to correlate the molecular findings versus HPV infection suggestive clinical findings. Biopsies from 50 patients (37 HGSILs and 13 UCC) histopathologically diagnosed were studied. The presence of HPV were detected by means of the polymerase chain reaction (PCR) using consensus primers for types 6, 11, 16, 18, 31, 33, 35, and 58 among others, as well as specific primers for some of them. The frequencies for HPV 16, 18, 33, 35, and 58 in HGSIL samples were 24.3, 2.7, 0, 5.4 and 16.2% respectively. In UCC samples were 61.5, 7.7, 0, 0 and 15.4% with significative differences only for HPV 16. Clinical findings (histologic, colposcopic and histopathologic), showed deficient diagnostic accuracy in the identification of HPV 16 in HGSIL, wich resulted less frequent and there is a high frequency of HPV. These results are similar to those previously described in our country and the other populations, with the exception of HPV16 in HGSIL, wich resulted less frequent and there is a high frequency of HPV 58 in our region. When analyzing clinical features with the presence of HPV DNA, we conclude that these are insufficient to discard or establish the possibility of HPV infection in patients with HGSIL's and UUC.

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.

Background: The MPS-I is an autosomal recessive disorder caused by mutations in the IDUA gene that induce to a deficiency of glycosidase alpha-L-iduronidase that is required for degradation of heparan and dermatan sulfate. This disorder expresses a wide range of clinical symptoms., Methods: Kpnl (K) and VNTR (V) intragenic polymorphisms at the IDUA gene were studied in mestizo and Huichol Indian Mexican populations as well in 13 MPS-I patients. Data from Australian normal and MPS-I (2-4) individuals were also studied., Results: Genotypes for IDUA K and V sites in Mexicans were in agreement with Hardy-Weinberg expectations, except for site K in Huichols. Individually, allele frequency distributions were different (p < 0.05) in the two normal groups for the V site. K-V haplotype frequency distributions (HFDs) in these two normal groups were also different as compared with normal Australians. In Mexican MPS-I patients, HFD was different (p < 0.05) with respect to both Mexican normal groups, and non-different when compared with normal or MPS-I Australians. This can be taken as evidence of linkage disequilibrium between K-V polymorphism and MPS-I gene mutation(s) at the IDUA region. A similar finding was reported. However, disequilibrium in Mexicans was determined by haplotypes different from those in Australia. In Mexican MPS-I patients, haplotype K2-V1 is increased and K1-V3 decreased with respect to the Mexican mestizo (p < 0.05), while in Australians, MPS-I patients had an increase of haplotypes K2-V2 and K1-V2 with respect to expected frequency., Conclusions: The similar HFD between Mexican and Australian MPS-I patients suggests a common genetic origin, that MPS-I mutations were introduced to Mexico by Spaniards, and that such mutations predate the dispersion between Mexican and Australian Caucasian ancestors. The differences in disequilibrium are explained rather by genetic drift.

We have analyzed 45 unrelated Northwestern Mexican patients with Cystic Fibrosis for 10 known CF mutations (DF508, G542X, G551D. R553X, W1282X, NI303K, R334W, R347H, S549R, and R1162X). Screening was performed on exons 7, 10, 11, 19, 20 and 21 using standard methods such as polymerase chain reactions, reverse dot blot hybridization (non-radioactive), and restriction enzyme digestion. The analysis for these ten mutations permitted the identification of only two mutations in 37.7% of CF chromosomes in this sample. The major mutation, delta F508, accounts for 34.4% of CF chromosomes. Of the 45 CF patients 9 (20.0%) were homozygous delta F508 deletion, 11 (24.4%) were heterozygous for the delta F508 mutation and an unknown mutation. One additional mutation G542X was also found in 3 chromosomes in our population (3.3%). Two patients were documented to be a compound heterozygote for DF508/G542X, and other one heterozygous for G542X and an unknown mutation. Therefore 62.2% of chromosomes remain uncharacterized.

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.