A simple RNA preparation method for SARS-CoV-2 detection by RT-qPCR.

The technique RT-qPCR for viral RNA detection is the current worldwide strategy used for early detection of the novel coronavirus SARS-CoV-2. RNA extraction is a key pre-analytical step in RT-qPCR, often achieved using commercial kits. However, the magnitude of the COVID-19 pandemic is causing disruptions to the global supply chains used by many diagnostic laboratories to procure the commercial kits required for RNA extraction. Shortage in these essential reagents is even more acute in developing countries with no means to produce kits locally. We sought to find an alternative procedure to replace commercial kits using common reagents found in molecular biology laboratories. Here we report a method for RNA extraction that takes about 40 min to complete ten samples, and is not more laborious than current commercial RNA extraction kits. We demonstrate that this method can be used to process nasopharyngeal swab samples and yields RT-qPCR results comparable to those obtained with commercial kits. Most importantly, this procedure can be easily implemented in any molecular diagnostic laboratory. Frequent testing is crucial for individual patient management as well as for public health decision making in this pandemic. Implementation of this method could maintain crucial testing going despite commercial kit shortages.

Eficacia en el control de la anticoagulación de los diferentes fármacos antagonistas de la vitamina K disponibles en Chile

Background: Vitamin K antagonist medications (VKA) are essential for the prevention of thromboembolic events, but their effectiveness is influenced by multiple factors, such as the type of medication chosen. Aim: To evaluate the efficacy in anticoagulant control of the bioequivalent and non-bioequivalent drugs of acenocoumarol compared to the reference drug. To evaluate the efficacy of warfarin bioequivalents available in Chile. To contrast the overall anticoagulant control efficacy between acenocoumarol and warfarin. Material and Methods: The results of 69333 outpatient oral anticoagulation controls were analyzed. Patient were separated in groups according to the drug that they used. Subsequently, the proportions of controls outside the range for each of acenocoumarol and warfarin bioequivalent drugs were compared. Acenocoumarol non-bioequivalent drugs were also compared with the reference drug. Acenocoumarol was compared with warfarin. Results: Acenocoumarol bioequivalent drugs and the reference drug had a similar proportion of controls outside the range (Odds ratios (OR) 0.812; 0.969; 0.974 and 0.963). Non-bioequivalent drugs had a higher proportion than the reference drug (OR 1.561 and 2.037). Both warfarin brands have a similar proportion of controls outside of the range (OR 1.050). Acenocoumarol compared to warfarin had a significant higher proportion of controls outside the range (OR 1.191). Conclusions: The pharmacological presentation of vitamin K antagonists could influence anticoagulant control. Therefore, it is not prudent to switch these presentations frequently.

Mutations in sphingolipid metabolism genes are associated with ADHD.

Attention deficit hyperactivity disorder (ADHD) is the most prevalent neurodevelopmental disorder in children, with genetic factors accounting for 75-80% of the phenotypic variance. Recent studies have suggested that ADHD patients might present with atypical central myelination that can persist into adulthood. Given the essential role of sphingolipids in myelin formation and maintenance, we explored genetic variation in sphingolipid metabolism genes for association with ADHD risk. Whole-exome genotyping was performed in three independent cohorts from disparate regions of the world, for a total of 1520 genotyped subjects. Cohort 1 (MTA (Multimodal Treatment study of children with ADHD) sample, 371 subjects) was analyzed as the discovery cohort, while cohorts 2 (Paisa sample, 298 subjects) and 3 (US sample, 851 subjects) were used for replication. A set of 58 genes was manually curated based on their roles in sphingolipid metabolism. A targeted exploration for association between ADHD and 137 markers encoding for common and rare potentially functional allelic variants in this set of genes was performed in the screening cohort. Single- and multi-locus additive, dominant and recessive linear mixed-effect models were used. During discovery, we found statistically significant associations between ADHD and variants in eight genes (GALC, CERS6, SMPD1, SMPDL3B, CERS2, FADS3, ELOVL5, and CERK). Successful local replication for associations with variants in GALC, SMPD1, and CERS6 was demonstrated in both replication cohorts. Variants rs35785620, rs143078230, rs398607, and rs1805078, associated with ADHD in the discovery or replication cohorts, correspond to missense mutations with predicted deleterious effects. Expression quantitative trait loci analysis revealed an association between rs398607 and increased GALC expression in the cerebellum.

[Anticoagulant efficacy of different pharmacological presentations of vitamin K antagonists]. / Eficacia en el control de la anticoagulación de los diferentes fármacos antagonistas de la vitamina K disponibles en Chile.

BACKGROUND: Vitamin K antagonist medications (VKA) are essential for the prevention of thromboembolic events, but their effectiveness is influenced by multiple factors, such as the type of medication chosen. AIM: To evaluate the efficacy in anticoagulant control of the bioequivalent and non-bioequivalent drugs of acenocoumarol compared to the reference drug. To evaluate the efficacy of warfarin bioequivalents available in Chile. To contrast the overall anticoagulant control efficacy between acenocoumarol and warfarin. MATERIAL AND METHODS: The results of 69333 outpatient oral anticoagulation controls were analyzed. Patient were separated in groups according to the drug that they used. Subsequently, the proportions of controls outside the range for each of acenocoumarol and warfarin bioequivalent drugs were compared. Acenocoumarol non-bioequivalent drugs were also compared with the reference drug. Acenocoumarol was compared with warfarin. RESULTS: Acenocoumarol bioequivalent drugs and the reference drug had a similar proportion of controls outside the range (Odds ratios (OR) 0.812; 0.969; 0.974 and 0.963). Non-bioequivalent drugs had a higher proportion than the reference drug (OR 1.561 and 2.037). Both warfarin brands have a similar proportion of controls outside of the range (OR 1.050). Acenocoumarol compared to warfarin had a significant higher proportion of controls outside the range (OR 1.191). CONCLUSIONS: The pharmacological presentation of vitamin K antagonists could influence anticoagulant control. Therefore, it is not prudent to switch these presentations frequently.

High prevalence of undiagnosed liver cirrhosis and advanced fibrosis in type 2 diabetic patients.

UNLABELLED:  Background. Patients with type 2 diabetes mellitus (T2DM) are at risk for developing end-stage liver disease due to nonalcoholic steatohepatitis (NASH), the aggressive form of non-alcoholic fatty liver disease (NAFLD). Data on prevalence of advanced fibrosis among T2DM patients is scarce. AIM: To evaluate prevalence of steatosis, advanced fibrosis and cirrhosis using non-invasive methods in T2DM patients. MATERIAL AND METHODS: 145 consecutive T2DM patients (> 55 years-old) were prospectively recruited. Presence of cirrhosis and advanced fibrosis was evaluated by magnetic resonance imaging (MRI) and NAFLD fibrosis score (NFS) respectively. Exclusion criteria included significant alcohol consumption, markers of viral hepatitis infection or other liver diseases. Results are expressed in percentage or median (interquartile range). RESULTS: 52.6% of patients were women, the median age was 60 years old (57-64), mean BMI was 29.6 ± 4.7 kg/m2 and diabetes duration was 7.6 ± 6.9 years. A high prevalence of liver steatosis (63.9%), advanced fibrosis assessed by NFS (12.8%) and evidence of liver cirrhosis in MRI (6.0%) was observed. In a multivariate analysis GGT > 82 IU/L (P = 0.004) and no alcohol intake (P = 0.032) were independently associated to advanced fibrosis. CONCLUSION: A high frequency of undiagnosed advanced fibrosis and cirrhosis was observed in non-selected T2DM patients. Screening of these conditions may be warranted in this patient population.

Low serum sphingolipids in children with attention deficit-hyperactivity disorder.

BACKGROUND: Attention deficit-hyperactivity disorder (ADHD) is the most prevalent neuropsychiatric condition in childhood. ADHD is a multifactorial trait with a strong genetic component. One neurodevelopmental hypothesis is that ADHD is associated with a lag in brain maturation. Sphingolipids are essential for brain development and neuronal functioning, but their role in ADHD pathogenesis is unexplored. We hypothesized that serum sphingolipid levels distinguish ADHD patients from unaffected subjects. METHODS: We characterized serum sphingolipid profiles of ADHD patients and two control groups: non-affected relatives and non-affected subjects without a family history of ADHD. Sphingolipids were measured by LC-MS/MS in 77 participants (28 ADHD patients, 28 related controls, and 21 unrelated controls). ADHD diagnosis was based on the Diagnostic and Statistical Manual of Mental Disorders (DSM IV-TR). Diagnostic criteria were assessed by two independent observers. Groups were compared by parametrical statistics. RESULTS: Serum sphingomyelins C16:0, C18:0, C18:1, C24:1, ceramide C24:0, and deoxy-ceramide C24:1 were significantly decreased in ADHD patients at 20-30% relative reductions. In our sample, decreased serum sphingomyelin levels distinguished ADHD patients with 79% sensitivity and 78% specificity. CONCLUSIONS: Our results showed lower levels of all major serum sphingomyelins in ADHD. These findings may reflect brain maturation and affect neuro-functional pathways characteristic for ADHD.

Comparison of Lipoprotein-Associated Phospholipase A2 and High Sensitive C-Reactive Protein as Determinants of Metabolic Syndrome in Subjects without Coronary Heart Disease: In Search of the Best Predictor.

High sensitivity C-reactive protein (hsCRP) is a marker of metabolic syndrome (MS) and cardiovascular (CV) disease. Lipoprotein-associated phospholipase A2 (Lp-PLA2) also predicts CV disease. There are no reports comparing these markers as predictors of MS. Methods. Cross-sectional study comparing Lp-PLA2 and hsCRP as predictors of MS in asymptomatic subjects was carried out; 152 subjects without known atherosclerosis participated. Data were collected on demographics, cardiovascular risk factors, anthropometric and biochemical measurements, and hsCRP and Lp-PLA2 activity levels. A logistic regression analysis was performed with each biomarker and receiver operating characteristic (ROC) curves were constructed for MS. Results. Mean age was 46 ± 11 years, and 38% of the subjects had MS. Mean Lp-PLA2 activity was 185 ± 48 nmol/mL/min, and mean hsCRP was 2.1 ± 2.2 mg/L. Subjects with MS had significantly higher levels of Lp-PLA2 (P = 0.03) and hsCRP (P < 0.0001) than those without MS. ROC curves showed that both markers predicted MS. Conclusion. Lp-PLA2 and hsCRP are elevated in subjects with MS. Both biomarkers were independent and significant predictors for MS, emphasizing the role of inflammation in MS. Further research is necessary to determine if inflammation predicts a higher risk for CV events in MS subjects.

Conductas de riesgo y prevalencia de Chlamydia trachomatis en presos según el tiempo de estancia en prisión / Risk behaviours and Chlamydia trachomatis prevalence in prisoners by length of stay in prison

Fundamento y objetivo: La población joven penitenciaria presenta elevadas conductas de riesgo y una precariedad socioeconómica que incrementa su vulnerabilidad frente a la adquisición de Chlamydia trachomatis (CT). Monitorizar su prevalencia ayudará a reducir las tasas de infección. Pacientes y métodos: Estudio transversal a partir de una muestra de conveniencia de presos de 18-25 años. Se obtuvieron muestras de orina para determinar CT. Se utilizó un cuestionario estandarizado anónimo para recoger las variables de estudio. Resultados: La prevalencia global de CT fue del 11%, significativamente superior en aquellos con menos de un año de estancia en prisión, presentando también frecuencias más elevadas en las conductas de riesgo, disminuyendo estas en aquellos que llevaban más de un año presos. Conclusiones: Los valores de prevalencia obtenidos dan una idea de la concentración de la población vulnerable a esta afección en las cárceles y subrayan la necesidad de continuar con los programas de prevención y control de infecciones de transmisión sexual (ITS). El hecho de estar mayor tiempo preso disminuyó los comportamientos de riesgo. Por tanto, creemos importante el cribado de ITS en el momento del ingreso, ya que hay una mayor probabilidad de estar infectado, e incidir en ese momento en la educación sexual, puesto que es cuando presentan conductas de riesgo más elevadas, que son las que probablemente realizaban cuando estaban en libertad

Background and objective: Young prisoners have high-risk behaviors and socio-economic insecurity that increases vulnerability for Chlamydia trachomatis (CT) acquisition. Monitoring its prevalence will help to reduce infection rates. Patients and methods: Cross-sectional study from a convenience sample of prisoners aged 18-25 years. Urine samples were obtained to determine CT. A standardized and anonymous questionnaire was used to collect the study variables. Results: The overall CT prevalence was 11%, significantly higher in those with less than one year in prison, who also presented higher frequencies in risk behaviors, while these were reduced in those who had been imprisoned for more than a year. Conclusions: The prevalence values obtained give an idea of the concentration of the population vulnerable to this disease in prisons and underscore the need to continue programs for the prevention and control of sexual transmitted infections (STIs). Being imprisoned longer decreased risk behaviors; therefore, it is important to screen for STIs upon admission because they are more likely to be infected and it would be thus possible to influence at that time in sex education because, at that time, risk behaviors occur more commonly, which are most likely done when they were free

[Risk behaviours and Chlamydia trachomatis prevalence in prisoners by length of stay in prison]. / Conductas de riesgo y prevalencia de Chlamydia trachomatis en presos según el tiempo de estancia en prisión.

BACKGROUND AND OBJECTIVE: Young prisoners have high-risk behaviors and socio-economic insecurity that increases vulnerability for Chlamydia trachomatis (CT) acquisition. Monitoring its prevalence will help to reduce infection rates. PATIENTS AND METHODS: Cross-sectional study from a convenience sample of prisoners aged 18-25 years. Urine samples were obtained to determine CT. A standardized and anonymous questionnaire was used to collect the study variables. RESULTS: The overall CT prevalence was 11%, significantly higher in those with less than one year in prison, who also presented higher frequencies in risk behaviors, while these were reduced in those who had been imprisoned for more than a year. CONCLUSIONS: The prevalence values obtained give an idea of the concentration of the population vulnerable to this disease in prisons and underscore the need to continue programs for the prevention and control of sexual transmitted infections (STIs). Being imprisoned longer decreased risk behaviors; therefore, it is important to screen for STIs upon admission because they are more likely to be infected and it would be thus possible to influence at that time in sex education because, at that time, risk behaviors occur more commonly, which are most likely done when they were free.

Niveles de fosfolipasa A2 asociada a lipoproteína en sujetos sin enfermedad coronaria con riesgo cardiovascular variable / Association of lipoprotein-associated phospholipase activity A2 with cardiovascular risk factors

Background:Lipoprotein-associated phospholipase A2 (Lp-PLA2) is an inflammatory biomarker involved in atherosclerosis and directly associated with cardiovascular events. Aim: To determine Lp-PLA2 levels in asymptomatic subjects with differing cardiovascular risk. Material and Methods: We studied 152 subjects aged 46 ± 11 years (69 women). We recorded traditional cardiovascular risk factors, creatinine, ultrasensitive C-reactive protein, fibrinogen, fasting lipids, blood sugar and activity levels of Lp-PLA2. Cardiovascular risk was classified according to the number of risk factors of each subject (0,1-2 or ≥ 3 risk factors). Besides, we calculated global Framingham risk score. Results: The average Framingham score of participants was 6%. Twenty percent of participants had no risk factors, 46% had 1 or 2 and 34% had ≥ 3. Mean Lp-PLA2 levels were 185 ± 48 nmol/ml/min (201 ± 49 in men and 166 ± 38 in women). Lp-PLA2 correlated significantly (p < 0,05 for all) with non-HDL cholesterol, LDL, HDL, creatinine, waist circumference, body mass index and Framingham risk score. There was no correlation with blood sugar, C-reactive protein, fibrinogen or smoking status. Lp-PLA2 levels were significantly higher according to the number of risk factors: 0 factors: 163 ± 43, 1-2 factors: 185 ± 45 and ≥ 3 factors: 201 ± 47 nmol/ml/min, respectively. Linear regression analysis showed that the best predictor of Lp-PLA2 was non-HDL cholesterol (β= 0,74; p < 0,0001). Conclusions: Lp-PLA2 activity increased along with the number of cardiovascular risk factors and was correlated mainly with non -HDL cholesterol.

Prevalencia de síndrome de Gilbert y sus determinantes genéticas en población chilena / Prevalence of Gilbert syndrome and its genetic determinants in Chile

Background: In Europeans the TATA box TA7 repeat promoter variant in the UGT1A1 gene (UGT1A1*28) is the major determinant of bilirubin levels. Aim: To study the prevalence of Gilbert Syndrome (GS) and its genetic determinants in Chile. Material and Methods: Three different studies were conducted. The prevalence of GS in Chile was assessed in 991 subjects with normal liver tests (ALT and GGT) from the 2nd National Health Survey. We defined GS as a total bilirubin (TB) between 1.4-5mg/dL. The second study assessed the genotype prevalence of SNP rs6742078 (in LD with UGT1A1*28) and rs4149056 in 500 DNA samples of non-related Hispanics. Finally, a case-control study was designed to assess the phenotype-genotype correlation. UGT1A1*28 and rs4149056 variants were determined by direct sequencing and allelic discrimination assays (TaqMan), respectively. Results: Prevalence of GS in the general Chilean population was 2.6% (4.5% in males and 0.5% in female). No correlation with age, educational level or home location was found. Genotypes for UGT1A1*28 (TA6/6 50.5%, TA6/7 37.8%, TA7/7 11.7%) and rs4149056 (TT 74.1%, CT 22.8%, and CC 3.1%) variants were similar to Europeans. In the case-control study, most patients with GS were homozygotes for UGT1A1*28 (TA7/7, 74%). Of note, 44% of patients with intermediate TB levels were also TA7/7, compared to 7% in normal subjects. SLCO1B1 genotype was not correlated with TB levels. Conclusions: While the prevalence of GS was lower in Chile compared to Europeans (~5%), the prevalence of UGT1A1*28 homozygotes was similar (~12%). In Chilean Hispanics, the UGT1A1*28 variant explain 75% of GS phenotype.

[Prevalence of Gilbert syndrome and its genetic determinants in Chile]. / Prevalencia de síndrome de Gilbert y sus determinantes genéticas en población chilena.

BACKGROUND: In Europeans the TATA box TA7 repeat promoter variant in the UGT1A1 gene (UGT1A1*28) is the major determinant of bilirubin levels. AIM: To study the prevalence of Gilbert Syndrome (GS) and its genetic determinants in Chile. MATERIAL AND METHODS: Three different studies were conducted. The prevalence of GS in Chile was assessed in 991 subjects with normal liver tests (ALT and GGT) from the 2nd National Health Survey. We defined GS as a total bilirubin (TB) between 1.4-5mg/dL. The second study assessed the genotype prevalence of SNP rs6742078 (in LD with UGT1A1*28) and rs4149056 in 500 DNA samples of non-related Hispanics. Finally, a case-control study was designed to assess the phenotype-genotype correlation. UGT1A1*28 and rs4149056 variants were determined by direct sequencing and allelic discrimination assays (TaqMan), respectively. RESULTS: Prevalence of GS in the general Chilean population was 2.6% (4.5% in males and 0.5% in female). No correlation with age, educational level or home location was found. Genotypes for UGT1A1*28 (TA6/6 50.5%, TA6/7 37.8%, TA7/7 11.7%) and rs4149056 (TT 74.1%, CT 22.8%, and CC 3.1%) variants were similar to Europeans. In the case-control study, most patients with GS were homozygotes for UGT1A1*28 (TA7/7, 74%). Of note, 44% of patients with intermediate TB levels were also TA7/7, compared to 7% in normal subjects. SLCO1B1 genotype was not correlated with TB levels. CONCLUSIONS: While the prevalence of GS was lower in Chile compared to Europeans (~5%), the prevalence of UGT1A1*28 homozygotes was similar (~12%). In Chilean Hispanics, the UGT1A1*28 variant explain 75% of GS phenotype.

[Association of lipoprotein-associated phospholipase activity A2 with cardiovascular risk factors]. / Niveles de fosfolipasa A2 asociada a lipoproteína en sujetos sin enfermedad coronaria con riesgo cardiovascular variable.

BACKGROUND: Lipoprotein-associated phospholipase A2 (Lp-PLA2) is an inflammatory biomarker involved in atherosclerosis and directly associated with cardiovascular events. AIM: To determine Lp-PLA2 levels in asymptomatic subjects with differing cardiovascular risk. MATERIAL AND METHODS: We studied 152 subjects aged 46 ± 11 years (69 women). We recorded traditional cardiovascular risk factors, creatinine, ultrasensitive C-reactive protein, fibrinogen, fasting lipids, blood sugar and activity levels of Lp-PLA2. Cardiovascular risk was classified according to the number of risk factors of each subject (0,1-2 or ≥ 3 risk factors). Besides, we calculated global Framingham risk score. RESULTS: The average Framingham score of participants was 6%. Twenty percent of participants had no risk factors, 46% had 1 or 2 and 34% had ≥ 3. Mean Lp-PLA2 levels were 185 ± 48 nmol/ml/min (201 ± 49 in men and 166 ± 38 in women). Lp-PLA2 correlated significantly (p < 0,05 for all) with non-HDL cholesterol, LDL, HDL, creatinine, waist circumference, body mass index and Framingham risk score. There was no correlation with blood sugar, C-reactive protein, fibrinogen or smoking status. Lp-PLA2 levels were significantly higher according to the number of risk factors: 0 factors: 163 ± 43, 1-2 factors: 185 ± 45 and ≥ 3 factors: 201 ± 47 nmol/ml/min, respectively. Linear regression analysis showed that the best predictor of Lp-PLA2 was non-HDL cholesterol (ß = 0,74; p < 0,0001). CONCLUSIONS: Lp-PLA2 activity increased along with the number of cardiovascular risk factors and was correlated mainly with non -HDL cholesterol.

Is my patient a bleeder? A diagnostic framework for mild bleeding disorders.

Congenital mild bleeding disorders (MBDs) are very prevalent and are the source of frequent diagnostic problems. Most MBDs are categorized as disorders of primary hemostasis (ie, type 1 VWD and platelet function disorders), but mild or moderate deficiencies of clotting factors and some rare hyperfibrinolytic disorders are also included. These patients have abnormal bleeding from the skin and mucous membranes, menorrhagia, and disproportionate hemorrhages after trauma, invasive procedures, and surgery. This review addresses the main problems that physicians and hemostasis laboratories confront with the diagnosis of these patients, including: discerning normal/appropriate from pathological bleeding, the role and yield of screening tests, the lack of distinctive bleeding pattern among the different diseases, the inherent difficulties in the diagnosis of type 1 VWD and the most common platelet functional disorders, improvements in assays to measure platelet aggregation and secretion, and the evidence that most of the patients with MBDs end up without a definite diagnosis after exhaustive and repeated laboratory testing. Much research is needed to determine the pathogenesis of bleeding in MBD patients. Better standardization of current laboratory assays, progress in the knowledge of fibrinolytic mechanisms and their laboratory evaluation, and new understanding of the factors contributing to platelet-vessel wall interaction, along with the corresponding development of laboratory tools, should improve our capacity to diagnose a greater proportion of patients with MBDs.

Insulinemia e índice HOMA en niños y adolescentes chilenos / Normal plasma insulin and HOMA values among chilean children and adolescents

Background: Plasma insulin and HOMA (homeostasis model assessment) index, used to determine insulin resistance, do not have local standard values for children and adolescents in Chile. Aim: To establish the normal reference intervals for insulin and HOMA in children and adolescents aged 10-15 years, according to sex and puberal maturation. Material and Methods: A cross-sectional study of 2,153 children and adolescents from Puente Alto County was performed, during 2009 and 2010. Anthropometry and self-report of puberal maturation were assessed. Fasting glucose (hexoquinase) and insulin blood levels (chemiluminiscence), were determined and HOMA index was calculated. Percentile distributions of these variables were calculated. Results: The reference group included only subjects with normal body mass index and fasting blood glucose (n = 1,192). Girls had higher insulin and HOMA values than boys (12.5 ± 6.0 and 9.1 ± 4.9 μϋ/mL (p < 0.01) and 2.7 ± 1.4 and 2.1 ± 1,1 (p < 0.01), respectively). Subjects with Tanner I and IIpuberal stages had lower insulin and HOMA mean values than subjects with Tanner III and IV (9.0 ± 4.3 and 12.5 ± 6.2μϋ/ml (p < 0.01) and2.0 ± 1 and2.8 ± 1.4 (p < 0.01), respectively). Conclusions: The 90th percentile of insulin and HOMA distributions according to sex and maturation, was selected as the upper cut-off point to identify individuals with insulin resistance. HOMA cutoff point for Tanner I and II boys was 3.2, for Tanner I and II girls was 4.1, for Tanner III and IV boys was 4.2 and for Tanner III and IV girls was 5.0.

[Introns 1 and 22 inversions and F8 gene sequencing for molecular diagnosis of hemophilia A in Chile]. / Análisis de las inversiones del intrón 1 y 22 y secuenciación del gen F8 para el diagnóstico genético-molecular de hemofilia A en Chile.

BACKGROUND: Hemophilia A is an inherited disorder caused by alterations in factor VIII gene (F8) located on the X-chromosome, the intron 22 inversion being the most common mutation. The rest are predominantly point mutations distributed along this large gene of 26 exons. AIM: To implement a molecular diagnostic test to detect mutations in the F8 gene in Chilean patients with Hemophilia A. MATERIAL AND METHODS: To validate the testing methods, we analyzed samples with intron 22 and intron 1 inversion, and with point mutations previously studied, as well as one subject without Hemophilia. We also studied unrelated Chilean patients with Hemophilia A and their female relatives for carrier testing. Intron 22 and intron 1 inversions were studied by long distance polymerase chain reaction (PCR) and point mutations by sequencing the coding and promoter regions of the F8 gene. RESULTS: The results obtained in all samples used for validation were concordant with those obtained previously. In the Chilean patients, the intron 22 inversion and point mutations previously described were observed. In 6 out of 9 patients with mild Hemophilia A we found the same mutation (Arg2159Cys) in exon 23, which has been described as prevalent in mild Hemophilia A. CONCLUSIONS: The analysis of intron 22 and intron 1 inversions, as well as of point mutations in the F8 gene will help us to confirm the diagnosis in patients with severe, moderate and mild Hemophilia A, and also it will allow us to perform carrier testing and to provide better genetic counseling.

Novel loci involved in platelet function and platelet count identified by a genome-wide study performed in children.

BACKGROUND: Genome-wide association studies are currently identifying new loci with potential roles in thrombosis and hemostasis: these loci include novel polymorphisms associated with platelet function traits and count. However, no genome-wide study performed on children has been reported to date, in spite of the potential that these subjects have in genetic studies, when compared to adults, given the minimal degree of confounders, i.e., acquired and environmental factors, such as smoking, physical activity, diet, and drug or hormone intake, which are particularly important in platelet function. DESIGN AND METHODS: To identify new genetic variants involved in platelet reactivity and count, we performed a genome-wide association study on 75 children (8.5±1.8 years) using the Illumina Sentrix Human CNV370-Quad BeadChip containing 320,610 single nucleotide polymorphisms. Functional analyses included assessment of platelet aggregation and granule secretion triggered by different agonists (arachidonic acid, collagen, epinephrine, ADP), as well as platelet count. Associations were selected based on statistical significance and physiological relevance for a subsequent replication study in a similar sample of 286 children. RESULTS: We confirmed previously established associations with plasma levels of factors XII, VII and VIII as well as associations with platelet responses to ADP. Additionally, we identified 82 associations with platelet reactivity and count with a P value less than 10(-5). From the associations selected for further replication, we validated two single nucleotide polymorphisms with mildly increased platelet reactivity (rs4366150 and rs1787566) on the LPAR1 and MYO5B genes, encoding lisophosphatidic acid receptor-1 and myosin VB, respectively; and rs1937970, located on the NRG3 gene coding neuroregulin-3, associated with platelet count. CONCLUSIONS: Our genome-wide association study performed in children, followed by a validation analysis, led us to the identification of new genes potentially relevant in platelet function and biogenesis.

Análisis de las inversiones del intrón 1 y 22 y secuenciación del gen F8 para el diagnóstico genético-molecular de hemofilia A en Chile / Introns 1 and 22 inversions and F8 gene sequencing for molecular diagnosis of hemophilia A in Chile

Background: Hemophilia A is an inherited disorder caused by alterations in factor VIII gene (F8) located on the X-chromosome, the intron 22 inversion being the most common mutation. The rest are predominantly point mutations distributed along this large gene of 26 exons. Aim: To implement a molecular diagnostic test to detect mutations in the F8 gene in Chilean patients with Hemophilia A. Material and Methods: To validate the testing methods, we analyzed samples with intron 22 and intron 1 inversion, and with point mutations previously studied, as well as one subject without Hemophilia. We also studied unrelated Chilean patients with Hemophilia A and their female relatives for carrier testing. Intron 22 and intron 1 inversions were studied by long distance polymerase chain reaction (PCR) and point mutations by sequencing the coding and promoter regions of the F8 gene. Results: The results obtained in all samples used for validation were concordant with those obtained previously. In the Chilean patients, the intron 22 inversion and point mutations previously described were observed. In 6 out of 9 patients with mild Hemophilia A we found the same mutation (Arg2159Cys) in exon 23, which has been described as prevalent in mild Hemophilia A. Conclusions: The analysis of intron 22 and intron 1 inversions, as well as of point mutations in the F8 gene will help us to confirm the diagnosis in patients with severe, moderate and mild Hemophilia A, and also it will allow us to perform carrier testing and to provide better genetic counseling.

[Normal plasma insulin and HOMA values among Chilean children and adolescents]. / Insulinemia e índice HOMA en niños y adolescentes chilenos.

BACKGROUND: Plasma insulin and HOMA (homeostasis model assessment) index, used to determine insulin resistance, do not have local standard values for children and adolescents in Chile. AIM: To establish the normal reference intervals for insulin and HOMA in children and adolescents aged 10-15 years, according to sex and puberal maturation. MATERIAL AND METHODS: A cross-sectional study of 2,153 children and adolescents from Puente Alto County was performed, during 2009 and 2010. Anthropometry and self-report of puberal maturation were assessed. Fasting glucose (hexoquinase) and insulin blood levels (chemiluminiscence), were determined and HOMA index was calculated. Percentile distributions of these variables were calculated. RESULTS: The reference group included only subjects with normal body mass index and fasting blood glucose (n = 1,192). Girls had higher insulin and HOMA values than boys (12.5 ± 6.0 and 9.1 ± 4.9 µÏ‹/mL (p < 0.01) and 2.7 ± 1.4 and 2.1 ± 1,1 (p < 0.01), respectively). Subjects with Tanner I and II pubertal stages had lower insulin and HOMA mean values than subjects with Tanner III and IV (9.0 ± 4.3 and 12.5 ± 6.2µÏ‹/ml (p < 0.01) and2.0 ± 1 and2.8 ± 1.4 (p < 0.01), respectively). CONCLUSIONS: The 90th percentile of insulin and HOMA distributions according to sex and maturation, was selected as the upper cut-off point to identify individuals with insulin resistance. HOMA cutoff point for Tanner I and II boys was 3.2, for Tanner I and II girls was 4.1, for Tanner III and IV boys was 4.2 and for Tanner III and IV girls was 5.0.

Influence of the F12 -4 C>T polymorphism on hemostatic tests.

The common F12 -4 C>T polymorphism significantly regulates plasma levels of FXII, the first element of the intrinsic pathway of coagulation. Due to the robust effects that this pathway has on blood coagulation in vitro, the objective of our study was to evaluate the influence of this polymorphism on different hemostatic tests. We studied 46 hemostatic parameters in 566 participants: 280 patients with mucocutaneous bleeding and 286 controls. The F12 -4T allele, associated with reduced levels of FXII (P < 0.001), also significantly delayed the activated partial thromboplastin time (aPTT) expressed as aPTTr (ratio sample plasma/normal pooled plasma). Thus, both patients and controls carrying the T allele had higher aPTTr than C/C homozygous individuals (P < 0.001). Interestingly, 92% of healthy controls who had prolonged aPTTr carried the F12 -4T allele. Moreover, individuals with the F12 -4T allele also had less thrombin generation (assessed by endogenous thrombin potential, thrombin peak and time to achieve the peak of thrombin) using a test with low tissue factor concentration and explicit contact phase activation. Finally, both patients and controls carrying the F12 -4T allele also displayed significantly lower FIXc and FVIIc levels than C/C individuals (P < 0.01). For all associations except for FVIIc, a gene-dosage effect was observed, and homozygous TT individuals had the farthest values. Our study reveals a significant effect of the F12 -4 C>T polymorphism on hemostatic tests widely used in routine clinical practice.