Mutational Landscape of CEBPA in Mexican Pediatric Acute Myeloid Leukemia Patients: Prognostic Implications.

Background: In Mexico, the incidence of acute myeloid leukemia (AML) has increased in the last few years. Mortality is higher than in developed countries, even though the same chemotherapy protocols are used. CCAAT Enhancer Binding Protein Alpha (CEBPA) mutations are recurrent in AML, influence prognosis, and help to define treatment strategies. CEBPA mutational profiles and their clinical implications have not been evaluated in Mexican pediatric AML patients. Aim of the Study: To identify the mutational landscape of the CEBPA gene in pediatric patients with de novo AML and assess its influence on clinical features and overall survival (OS). Materials and Methods: DNA was extracted from bone marrow aspirates at diagnosis. Targeted massive parallel sequencing of CEBPA was performed in 80 patients. Results: CEBPA was mutated in 12.5% (10/80) of patients. Frameshifts at the N-terminal region were the most common mutations 57.14% (8/14). CEBPA biallelic (CEBPA BI) mutations were identified in five patients. M2 subtype was the most common in CEBPA positive patients (CEBPA POS) (p = 0.009); 50% of the CEBPA POS patients had a WBC count > 100,000 at diagnosis (p = 0.004). OS > 1 year was significantly better in CEBPA negative (CEBPA NEG) patients (p = 0.0001). CEBPA POS patients (either bi- or monoallelic) had a significantly lower OS (p = 0.002). Concurrent mutations in FLT3, CSF3R, and WT1 genes were found in CEBPA POS individuals. Their contribution to poor OS cannot be ruled out. Conclusion: CEBPA mutational profiles in Mexican pediatric AML patients and their clinical implications were evaluated for the first time. The frequency of CEBPA POS was in the range reported for pediatric AML (4.5-15%). CEBPA mutations showed a negative impact on OS as opposed to the results of other studies.

Profiling FLT3 Mutations in Mexican Acute Myeloid Leukemia Pediatric Patients: Impact on Overall Survival.

Background: Acute myeloid leukemia (AML) is the second most frequent leukemia in childhood. The FLT3 gene participates in hematopoietic stem cell proliferation. FLT3 mutations are recurrent in AML and influence prognosis. In Mexican pediatric AML patients, FLT3 mutational profile, and their clinical impact have not been evaluated. Aim of the study: This study aimed to identify the profile of FLT3 mutations in pediatric patients with de novo AML and to assess their possible influence on overall survival (OS) and other clinical features. Methods: Massive parallel target sequencing of FLT3 was performed in 80 patients. Results: FLT3 mutations [internal tandem duplication (ITD) or tyrosine kinase domain (TKD)] were identified in 24% of them. OS was significantly lower in FLT3 POS cases than in FLT3 NEG (p = 0.03). The average OS for FLT3 POS was 1.2 vs. 2.2 years in FLT3 NEG. There were no significant differences in the children's sex, age, percentage of blasts in bone marrow aspirate, or white blood cell count in peripheral blood at diagnosis between both groups. No differences were identified stratifying by the mutational load (high > 0.4) or type of mutation. The negative effect of FLT3 mutations was also observed in patients with acute promyelocytic leukemia (APL). Conclusions: FLT3 mutational profile is described in Mexican pediatric AML patients for the first time. Mutated FLT3 negatively impacts the outcome of AML patients, even considering the APL group. The clinical benefit from treatment with tyrosine kinase inhibitors in the FLT3 POS pediatric patients needs to be assessed in clinical trials. FLT3 testing may contribute to better risk stratification in our pediatric AML patients.

IFNG +874 A/T is associated with acute lymphoblastic leukemia in Mexican Mestizos.

Acute lymphoblastic leukemia (ALL), the most common type of cancer in children worldwide, has one of the highest incidence rates in Mexico. It is a multifactorial disease and different cytokine single nucleotide polymorphisms (SNP), have been associated with ALL expression. Few studies have been published analyzing IFNG +874 T/A and IL2 -330 G/T in this type of leukemia. These SNPs are involved in high or low expression, and are central to cellular immunity, influencing greatly tumor growth. The purpose of this work was to explore the association of IFNG +874 A/T (rs2430561) and IL2 -330 G/T (rs2069762) SNPs with ALL susceptibility and/or protection in 488 Mexican Mestizos patients, as compared to 950 Mexican Mestizo healthy controls. The results demonstrated that IFNG +874 T allele (pc = 0.00004, OR = 0.673) and the TT genotype (pc = 0.00015, OR = 0.349), protect against ALL expression with no specific gender association; however, the TT homozygote genotype (vs. TA+AA) seems more protective in males (pc = 0.00683). IL2 -330 G/T does not contribute to the development of ALL. In healthy Mexicans, the most common genotypes for IL2 and IFNG, are the low cytokine producers, suggesting that the genetic background in this ethnic group, may be partly responsible for the high incidence of ALL. These results show for the first time in Mexicans, the relevant role that IFNG SNP has in the genetic etiology of ALL. Thus, a large group of patients belonging to different ethnicities will be very helpful to study in order to demonstrate if these SNPs contribute to the genetic etiology of ALL, as shown here in Mexican Mestizos.

Primary dengue virus infections induce differential cytokine production in Mexican patients.

Severe dengue pathogenesis is not fully understood, but high levels of proinflammatory cytokines have been associated with dengue disease severity. In this study, the cytokine levels in 171 sera from Mexican patients with primary dengue fever (DF) and dengue haemorrhagic fever (DHF) from dengue virus (DENV) 1 (n = 116) or 2 (n = 55) were compared. DF and DHF were defined according to the patient's clinical condition, the primary infections as indicated by IgG enzymatic immunoassay negative results, and the infecting serotype as assessed by real-time reverse transcription-polymerase chain reaction. Samples were analysed for circulating levels of interleukin (IL)-12p70, interferon (IFN)-γ, tumour necrosis factor (TNF)-α, IL-6, and IL-8 using a commercial cytometric bead array. Significantly higher IFN-γ levels were found in patients with DHF than those with DF. However, significantly higher IL-12p70, TNF-α, and IL-6 levels were associated with DHF only in patients who were infected with DENV2 but not with DENV1. Moreover, patients with DF who were infected with DENV1 showed higher levels of IL-12p70, TNF-α, and IL-6 than patients with DHF early after-fever onset. The IL-8 levels were similar in all cases regardless of the clinical condition or infection serotype. These results suggest that the association between high proinflammatory cytokine levels and dengue disease severity does not always stand, and it once again highlights the complex nature of DHF pathogenesis.

Primary dengue virus infections induce differential cytokine production in Mexican patients

Severe dengue pathogenesis is not fully understood, but high levels of proinflammatory cytokines have been associated with dengue disease severity. In this study, the cytokine levels in 171 sera from Mexican patients with primary dengue fever (DF) and dengue haemorrhagic fever (DHF) from dengue virus (DENV) 1 (n = 116) or 2 (n = 55) were compared. DF and DHF were defined according to the patient’s clinical condition, the primary infections as indicated by IgG enzymatic immunoassay negative results, and the infecting serotype as assessed by real-time reverse transcription-polymerase chain reaction. Samples were analysed for circulating levels of interleukin (IL)-12p70, interferon (IFN)-γ, tumour necrosis factor (TNF)-α, IL-6, and IL-8 using a commercial cytometric bead array. Significantly higher IFN-γ levels were found in patients with DHF than those with DF. However, significantly higher IL-12p70, TNF-α, and IL-6 levels were associated with DHF only in patients who were infected with DENV2 but not with DENV1. Moreover, patients with DF who were infected with DENV1 showed higher levels of IL-12p70, TNF-α, and IL-6 than patients with DHF early after-fever onset. The IL-8 levels were similar in all cases regardless of the clinical condition or infection serotype. These results suggest that the association between high proinflammatory cytokine levels and dengue disease severity does not always stand, and it once again highlights the complex nature of DHF pathogenesis.

A strong interferon response correlates with a milder dengue clinical condition.

BACKGROUND: Type 1 interferon (IFNα/ß) has a significant role in establishing protection against virus infections. It has been well documented by in vitro studies that dengue virus (DENV) activates a robust IFNα/ß response. However, DENV also induces a down-regulation of the JAK/STAT pathway, inhibiting the induction of interferon regulated genes. As a consequence, the role played by the IFN type 1 response in the protection of dengue patients is not fully understood. OBJECTIVE: To compare IFN-α levels in dengue patients with dengue fever (DF) or dengue hemorrhagic fever (DHF) undergoing primary or secondary infections. STUDY DESIGN: Two hundred and four serum samples were analyzed for IFN-α level by cytometric bead array. Patients' clinical condition was assigned following the WHO 1997 criteria and specific IgG and IgM antibodies were measured using commercial assays to determine primary and secondary infections. The infecting serotype was determined by qRT-PCR. RESULTS AND CONCLUSION: The IFN-α levels were found significantly higher in DF than DHF patients irrespective of the infecting serotype (DENV1 or 2), and were found to decline rapidly at day 3 after fever onset. For DENV2 infections, higher IFN-α level was found during primary than secondary infections. These results suggest that an early strong interferon response correlates with a better clinical condition.

HLA-DRB1 Class II antigen level alleles are associated with persistent HPV infection in Mexican women; a pilot study.

BACKGROUND: Persistent infection with high-risk human papillomavirus (HPV) is a major risk factor for malignant lesions and cervical cancer. A widely studied element in the search for genetic factors influencing risk HPV infection diseases is allelic variation of the human leukocyte antigen (HLA) locus. The study was designed to search for HLA susceptibility alleles contributing to the persistence of HPV infection in Mexican women. METHODS: A total of 172 subjects were divided into three groups: 1) HPV-persistent patients; 2) HPV-cleared; and 3) HPV-reinfected patients. They were screened for HPV types using a polymerase chain reaction (PCR). PCR-sequence specific oligonucleotide probes (PCR-SSOP) was used for HLA DRB1 and DQB1 typing. RESULTS: We observed that HLA-DQB1*0501 allele might be associated with susceptibility of reinfection with HPV (p = 0.01, OR = 4.9, CI 95% = 1.3 -18.7). Allele frequency of HLA-DRB1*14 was particularly reduced in patients with cancer when compared with the HPV-persistent group (p = 0.04), suggesting that this allele is a possible protective factor for the development of cervical cancer (OR = 2.98). HLA-DRB1*07 might be associated with viral clearance (p = 0.04). CONCLUSIONS: Genetic markers for HPV infection susceptibility are different in each population, in Mexicans several HLA-DQB1 alleles might be associated with an enhanced risk for viral persistence. In contrast, DRB1*14, seems to confer protection against cervical cancer.

Viral load in patients infected with dengue is modulated by the presence of anti-dengue IgM antibodies.

BACKGROUND: The measurement and detection of viremia and antigenemia in sera have been used as a marker of risk for dengue disease severity and diagnosis. However, evidence exists suggesting that levels of viremia and antigenemia are affected by the presence of specific antibodies. OBJECTIVE: To compare viral load and circulating NS1 levels in sera from patients positive or negative for dengue specific IgM antibodies. STUDY DESIGN: Three hundred and eighty serum samples were analyzed for viral load using qRT-PCR and for levels of circulating NS1 and the presence of specific antibodies using commercial EIAs. RESULTS AND CONCLUSION: Comparison of viremia levels in sera from patients positive or negative for dengue IgM antibodies showed that viral load was significantly higher (p≤0.0001) in patients negative for IgM antibodies. In contrast, levels of circulating NS1 were found unaffected by the presence of IgM (p=0.0038). Thus, dengue virus specific IgM antibodies in sera seem to be a strong negative modulator of viremia levels in patient's sera.

Determination of viremia and concentration of circulating nonstructural protein 1 in patients infected with dengue virus in Mexico.

Higher levels of viremia and circulating nonstructural protein 1 (NS1) have been associated with dengue disease severity. In this study, viremia and circulating NS1 levels were determined in 225 serum samples collected from patients in Mexico infected with dengue virus serotypes 1 and 2 (DENV-1 and DENV-2). Patients with dengue hemorrhagic fever (DHF) who were infected with DENV-1 showed higher levels of circulating NS1 than patients with dengue fever (DF) (P = 0.0175). Moreover, NS1 levels were higher in patients with primary infections with DENV-1 than in patient infected with DENV-2 (P < 0.0001) and in patients with primary infections with DENV-2 than in patients with secondary infections with DENV-2 (P = 0.0051). Unexpectedly, viremia levels were higher in patients with DF than in those with DHF infected with either DENV-1 or DENV-2 (P = 0.0019 and P = 0.001, respectively) and in patients with primary infections than those with secondary DENV-2 infections (P < 0.0001). Results indicate that levels of circulating NS1 vary according to the infecting serotype, immunologic status (primary or secondary infection), and dengue disease severity.

Evaluation of a novel commercial rapid test for dengue diagnosis based on specific IgA detection.

The performance of the novel commercial test ASSURE® Dengue IgA Rapid test (MP Diagnostics) was evaluated using a panel of 172 sera collected from dengue patients and 47 sera from healthy blood donors. The overall specificity and sensitivity were 61.0% and 85.1%, respectively. However, the positivity rate for IgA went from 33.3% for sera collected the same day of fever onset to 81.2% for sera collected 5 days after fever onset. Infections with serotype 2 viruses were detected more efficiently than those with serotype 1 viruses, and no sera from infections with serotypes 3 and 4 were available. In addition, the kit was twice more efficient at detecting secondary infections than at detecting primary infections. Finally, the ASSURE® test showed good repeatability and reproducibility. The results of this study suggest that the ASSURE® Dengue IgA Rapid test may become a useful and easy-to-use test for early dengue diagnosis.

HPV-16 and HLA-DRB1 alleles are associated with cervical carcinoma in Mexican Mestizo women.

The aim of this report was to investigate the contribution of HLA-DRB1/DQB1 alleles to the expression of cervical cancer (CC) and squamous intraepithelial lesion (SIL) in Mexican patients. A total of 257 women were included in the study: 61with low-grade squamous intraepithelial lesions (LSIL), 30 with high-grade (HSIL), 73 with CC and 93 healthy females. All were Mexican Mestizos. For HLA class II typing, PCR-SSOP methodology was used. HPV-16 viral DNA was detected by PCR with specific primers for E6-E7 region. HPV-16 was found in 52% of the patients with CC as well as in 19% of women with HSIL and in 12.5% of females with LSIL. HLA-DRB1∗04:03 (OR = 5.88) was found increased in patients with HSIL as compared with controls, although significance (p = 0.04) was lost after correction (pc =NS). HLA-DRB1∗04:03 seems to influence the risk for developing HSIL, disregarding the presence of HPV-16. HLA-DRB1∗01:01 (OR = 0.12; p = 0.01) may confer protection to the development of CC. An analysis performed stratifying by the presence of HPV-16 infection showed that the frequency of HLA-DRB1∗04:07 (OR = 2.71) was increased in CC patients infected with HPV-16, confirming that the HLA association is HPV dependent. These results shed light on the influence that this virus may have in the expression of CC in the susceptible host. Genetic background is, therefore, a crucial factor in understanding the etiopathogenesis of CC in HPV-positive patients.

[Age of onset of different malignant tumors in childhood]. / Edad de aparición de los diferentes tumores malignos en la infancia.

OBJECTIVE: To identify the main age of onset of different malignant tumors in childhood and to describe the distribution of the different tumors in each pediatric age group. MATERIAL AND METHODS: Descriptive survey was used. We reviewed the files of six Mexico City hospitals from 1980 to 1992. We included 4595 cases divided into 13 types of cancer. Peak age was defined when in that year we encountered a frequency equal to or below 10 % of the cases. RESULTS: Peak ages for hepatic, sympathetic nervous system, germ cell tumors, retinoblastoma and rhabdomyosarcoma were between 2 and 3 years of age. Wilms' tumor appeared between the first and fourth years; central nervous system tumors between 4 and 5 years; acute lymphoblastic leukemia between 2 and 4 years; non-Hodgkin's lymphomas between 3 and 6 years; Hodgkin's disease between 4 and 8 years; bone tumors between 10 and 14 years. In acute myeloid leukemia and carcinomas no age peak was found. CONCLUSIONS: Lymphomas present an age peak different from that reported in developed countries. In neonates and infants, the most frequent tumor was retinoblastoma.

Incidencia de las leucemias agudas en niños de la ciudad de México, de 1982 a 1991 / Incidence of acute leukemia in children of Mexico city; 1982 to 1991

Objetivo. Medir la tasa de incidencia de las leucemias agudas (LA) en las diferentes delegaciones políticas del Distrito Federal y evaluar si existe una tendencia significativa en dichos padecimientos en tales delegaciones. Material y métodos. Estudio longitudinal descriptivo realizado en seis hospitales de la ciudad de México, los que atienden a cerca de 97.5 por ciento de todos los niños con cáncer de esta ciudad. Los datos se capturaron de 1995 a 1996, y se analizaron en 1999, en el Hospital de Pediatría del Centro Médico Nacional Siglo XXI, del Instituto Mexicano del Seguro Social. Para cada delegación se cal-cularon la tasa de incidencia anual promedio, la tasa es-tandarizada y la razón estandarizada de morbilidad (REM) con intervalos de confianza al 95 por ciento (IC 95 por ciento). La tendencia se evaluó con la tasa de cambio promedio. Re-sultados. Se observó una tendencia al incremento en la incidencia de la leucemia aguda linfoblástica (LAL) en cinco delegaciones: Alvaro Obregón, Cuauhtémoc, Gustavo A. Madero, Izta-calco y Venustiano Carranza. En la leucemia aguda mieloblás-tica (LAM) no se notificaron cambios estadísticamente signi-ficativos en la incidencia en ninguna delegación política. Sólo con LAM se encontró una REM significativa y co-rrespondió a la delegación Alvaro Obregón (REM= 2.91, IC 95 por ciento 1.63 - 4.80). Las REM más altas se encontraron en el sur y suroeste de la ciudad. Conclusiones. Sólo se observó incremento en la incidencia de LAL en cinco delegaciones políticas. La incidencia más alta de LAM se encontró en la delegación Alvaro Obregón.