ARID5B, IKZF1, GATA3, CEBPE, and CDKN2A germline polymorphisms and predisposition to childhood acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most frequent type of pediatric cancer. Germline single nucleotide polymorphisms (SNPs), including ARID5B (rs10821936 T/C), IKZF1 (rs4132601 T/G), GATA3 (rs3824662 G/T), CEBPE (rs2239633 G/A), and CDKN2A (rs3731217 A/C) have been linked to pediatric ALL in different populations. Hitherto, no previous studies have tested the relationship between these SNPs and pediatric ALL in Gaza strip. Therefore, we investigated the association between these polymorphisms and the occurrence of childhood ALL in this part of Palestine. This case-control study recruited 100 healthy controls and 78 ALL patients. Allele-specific PCR (AS-PCR) technique was used for SNPs genotyping. Relevant statistical tests were used and the multifactor dimensionality reduction (MDR) approach was applied in the analysis of gene-gene interactions. Minor alleles of ARID5B rs10821936 T/C (p = 0.007) and IKZF1 rs4132601 T/G (p = 0.045) were significantly higher in ALL patients. The homozygous (TT) genotype of GATA3 rs3824662 G/T (p = 0.038), (CC) of ARID5B rs10821936 T/C (p = 0.008), and (AC and CC) genotypes of CDKN2A rs3731217 A/C (p < 0.0001) were significantly higher in ALL cases. On MDR analysis, the best model for ALL risk was the five-factor model combination of the examined SNPs (CVC = 10/10; TBA = 0.632; p < 0.0001). This work demonstrates the association of ARID5B rs10821936 T/C, IKZF1 rs4132601 T/G, GATA3 rs3824662 G/T, and CDKN2A rs3731217 A/C polymorphisms with increased risk of pediatric ALL among a patient cohort from Gaza Strip. Further studies with a larger sample size are needed in order to confirm these findings and test the value of these SNPs in prognosis and treatment sensitivity.

A Novel CEBPE Variant Causes Severe Infections and Profound Neutropenia

PURPOSE

Specific granule deficiency (SGD) is a rare inborn error of immunity resulting from loss-of-function variants in CEBPE gene (encoding for transcription factor C/EBPε). Although this genetic etiology has been known for over two decades, only a few patients with CEBPE variant-proven SGD (type I) have been reported. Herein, we describe two siblings with a novel homozygous CEBPE deletion who were noted to have profound neutropenia on initial evaluation. We aimed to evaluate the immunohematological consequences of this novel variant, including profound neutropenia.

METHODS

Light scatter characteristics of granulocytes were examined on various automated hematology analyzers. Phagocyte immunophenotype, reactive oxygen species generation, and Toll-like receptor (TLR) signaling were assessed using flow cytometry. Relative expression of genes encoding various granule proteins was studied using RT-PCR. Western blot analysis and luciferase reporter assay were performed to explore variant C/EBPε expression and function.

RESULTS

Severe infections occurred in both siblings. Analysis of granulocyte light scatter plots revealed automated hematology analyzers can provide anomalously low neutrophil counts due to abnormal neutrophil morphology. Neutrophils displayed absence/marked reduction of CD15/CD16 expression and overexpression (in a subset) of CD14/CD64. Three distinct populations of phagocytes with different oxidase activities were observed. Impaired shedding of CD62-ligand was noted on stimulation with TLR-4, TLR-2/6, and TLR-7/8 agonists. We demonstrated the variant C/EBPε to be functionally deficient.

CONCLUSION

Homozygous c.655_665del variant in CEBPE causes SGD. Anomalous automated neutrophil counts may be reported in patients with SGD type I. Aberrant TLR signaling might be an additional pathogenetic mechanism underlying immunodeficiency in SGD type I.

Novel Frameshift Autosomal Recessive Loss-of-Function Mutation in SMARCD2 Encoding a Chromatin Remodeling Factor Mediates Granulopoiesis

PURPOSE

Recently, a new form of congenital neutropenia that is caused by germline biallelic loss-of-function mutations in the SMARCD2 gene was described in four patients. Given the rarity of the condition, the clinical spectrum of the disease has remained elusive. We here report a new patient with a novel frameshift mutation and compare our patient with the previously reported SMARCD2-mutant patients, aiming to provide a more comprehensive understanding of the natural course of the disease.

METHODS

Clinical and laboratory findings of all reported patients were reviewed. Next-generation sequencing was performed to identify the causative genetic defect. Data on the hematopoietic stem cell transplantation including stem cell sources, conditioning regimen, engraftment, graft-versus-host disease, and infections were also collected.

RESULTS

An 11-year-old female patient had a variety of infections including sepsis, deep tissue abscesses, otitis, pneumonia, gingivitis, and diarrhea since infancy. A novel homozygous mutation in SMARCD2 (c.93delG, p.Ala32Argfs*80) was detected. Bone marrow examination showed hypocellularity and decreased neutrophils with diminished granules and myeloid dysplasia, but no blast excess as in previously reported patients. The neutropenia was non-responsive even to higher doses of granulocyte colony-stimulating factor (G-CSF); therefore, the patient was transplanted at 10 years of age from a HLA-A allele-mismatched unrelated donor using a reduced toxicity conditioning regimen and recovered successfully. Compared with the previous four cases, our patient showed longer survival before transplantation without blastic transformation.

CONCLUSION

Distinctive myeloid features and long-term follow-up including therapy options are presented for the newly described case of SMARCD2 deficiency. This disorder is apparent at infancy and requires early transplantation due to the unrelenting disease course despite conventional therapy.

Contributions of IKZF1, DDC, CDKN2A, CEBPE, and LMO1 Gene Polymorphisms to Acute Lymphoblastic Leukemia in a Yemeni Population

BACKGROUND

Genome-wide and candidate gene association studies have previously revealed links between a predisposition to acute lymphoblastic leukemia (ALL) and genetic polymorphisms in the following genes: IKZF1 (7p12.2; ID: 10320), DDC (7p12.2; ID: 1644), CDKN2A (9p21.3; ID: 1029), CEBPE (14q11.2; ID: 1053), and LMO1 (11p15; ID: 4004). In this study, we aimed to conduct an investigation into the possible association between polymorphisms in these genes and ALL within a sample of Yemeni children of Arab-Asian descent.

METHODS

Seven single-nucleotide polymorphisms (SNPs) in IKZF1, three SNPs in DDC, two SNPs in CDKN2A, two SNPs in CEBPE, and three SNPs in LMO1 were genotyped in 289 Yemeni children (136 cases and 153 controls), using the nanofluidic Dynamic Array (Fluidigm 192.24 Dynamic Array). Logistic regression analyses were used to estimate ALL risk, and the strength of association was expressed as odds ratios with 95% confidence intervals.

RESULTS

We found that the IKZF1 SNP rs10235796 C allele (p = 0.002), the IKZF1 rs6964969 A>G polymorphism (p = 0.048, GG vs. AA), the CDKN2A rs3731246 G>C polymorphism (p = 0.047, GC+CC vs. GG), and the CDKN2A SNP rs3731246 C allele (p = 0.007) were significantly associated with ALL in Yemenis of Arab-Asian descent. In addition, a borderline association was found between IKZF1 rs4132601 T>G variant and ALL risk. No associations were found between the IKZF1 SNPs (rs11978267; rs7789635), DDC SNPs (rs3779084; rs880028; rs7809758), CDKN2A SNP (rs3731217), the CEBPE SNPs (rs2239633; rs12434881) and LMO1 SNPs (rs442264; rs3794012; rs4237770) with ALL in Yemeni children.

CONCLUSION

The IKZF1 SNPs, rs10235796 and rs6964969, and the CDKN2A SNP rs3731246 (previously unreported) could serve as risk markers for ALL susceptibility in Yemeni children.

ARID5B, CEBPE and PIP4K2A Germline Genetic Polymorphisms and Risk of Childhood Acute Lymphoblastic Leukemia in Mexican Patients: A MIGICCL Study

BACKGROUND AND AIMS

Childhood acute lymphoblastic leukemia (ALL) is the leading cause of childhood cancer-related deaths worldwide. Multiples studies have shown that ALL seems to be originated by an interaction between environmental and genetic susceptibility factors. The ARID5B polymorphisms are among the most reproducible ALL associated-risk alleles in different populations. The aim of the present study was to examine the contribution of ARID5B, CEBPE, and PIP4K2 risk alleles for the development of ALL in children from Mexico City and Yucatan, Mexico.

METHODS

A study was conducted with a total of 761 unrelated subjects. Two hundred eighty five ALL cases (111 from Yucatan and 174 from Mexico City) and 476 healthy subjects. Genotyping included the rs7088318 (PIP4K2A), rs10821936 (ARID5B), rs7089424 (ARID5B) and rs2239633 (CEBPE) polymorphisms.

RESULTS

Associations between ALL and rs10821936 and rs7089424 ARID5B SNPs were found (OR = 1.9, 95% CI (1.5-2.4) and OR = 2.0, 95% CI (1.6-2.5), respectively). Moreover, a higher risk was observed in the homozygous risk genotypes of carriers from Mexico City (OR = 3.1, 95% CI (2.0-4.9) and OR 3.1, CI 95% (2.0-4.8), respectively). Otherwise, the rs7088318 (PIP4K2A) and rs2239633 (CEBPE) polymorphisms were not associated with ALL risk.

CONCLUSIONS

Our analysis suggests that ARID5B confers risk for childhood ALL in a Mexican population.

Association of genetic variation in IKZF1, ARID5B, CDKN2A, and CEBPE with the risk of acute lymphoblastic leukemia in Tunisian children and their contribution to racial differences in leukemia incidence

Recent genome-wide association studies (GWAS) focusing on pediatric acute lymphoblastic leukemia (ALL), the most common malignancy in children younger than 15 years old, have found evidence that single-nucleotide polymorphisms (SNPs) in IKZF1 (7p12.2), ARID5B (10q21.2), CDKN2A (9p21.3), and CEBPE (14q11.2) are strongly associated to the risk of developing pediatric ALL. These studies have been conducted in European and Thai populations, and it is unclear whether these observations generalize to other populations with a lower incidence of pediatric ALL. In order to explore the impact of these variants on pediatric ALL risk in the Tunisian population, we genotyped 58 cases of pediatric ALL and 150 controls for SNPs rs4132601 (7p12.2), rs7089424 (10q21.2), rs3731217 (9p21.3), and rs2239633 (14q11.2). Our results, which are consistent with findings in European populations, show that 3 SNPs, i.e., rs4132601 (P = .00116, odds ratio [OR] = 2.78, 95% confidence interval [CI] = [1.42, 5.87]), rs7089424 (P = .0022, OR = 0.49, 95% CI = [0.31, 0.79]), and rs2239633 (P = .0010, OR = 0.47, 95% CI = [0.29, 0.75]) are significantly associated with a higher risk of developing pediatric ALL (P < .05). Furthermore, we show differences in allele frequencies in SNPs between Tunisian and Caucasian and/or Thai populations (e.g., CEBPE, rs2239633; population attributable risk [PAR] ∼15-fold the PAR of Thai population). These differences, combined with differences in linkage disequilibrium structure between populations and differences in size between populations, may contribute to racial differences in pediatric ALL incidence.

A common genetic variation in CEBPE and acute lymphoblastic leukemia: a meta-analysis of the available evidence

Acute lymphoblastic leukemia (ALL) has been studied intensively for decades, but the details of its etiology and underlying mechanisms have yet to be fully elucidated. It is now generally acknowledged that genetic factors contribute greatly to the development of this disease. The gene encoding CCAAT/enhancer-binding protein ε (CEBPE) is involved in the development of leukemia, and in particular the rs2239633 single nucleotide polymorphism (SNP) of CEBPE. The association between rs2239633 and risk of ALL has been well studied, but remains unclear. Therefore, a meta-analysis was performed in this study to establish a more precise estimation of that relationship. A comprehensive literature search of the PubMed electronic database was conducted, and relevant studies published up to February 20, 2015 were selected for analysis. The references of the retrieved articles were also screened. The extracted data were analyzed statistically, and pooled odds ratios with 95% confidence intervals were calculated using Review Manager (version 5.2) to estimate the association strength. Finally, eleven studies were included in the meta-analysis. The pooled analyses revealed that rs2239633 was associated with an increased risk of childhood ALL in Caucasians under any contrast models (P<0.01). However, this SNP did not affect the risk of ALL in adulthood among Caucasians, or in childhood among East Asians. In conclusion, these findings confirm that the CEBPE rs2239633 SNP could be considered a good marker of pediatric ALL risk in Caucasians, but not in East Asians; it is not a good marker of adult ALL risk in Caucasians.

Meta-analysis of the association between CCAAT/enhancer binding protein-ε polymorphism and the risk of childhood acute lymphoblastic leukemia

CEBPE rs2239633 polymorphism has been implicated in susceptibility to childhood acute lymphoblastic leukemia (ALL) risk. Several studies investigated the association of this polymorphism with ALL in different populations. However, the results were contradictory. A meta-analysis was conducted to assess the association between CEBPE rs2239633 polymorphism and ALL susceptibility. Databases including Pubmed, EMBASE, Chinese National Knowledge Infrastructure (CNKI) and Wangfang were searched to find relevant studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of associations. A random-effects model was used. A significant association was found between CEBPE rs2239633 polymorphism and childhood ALL (OR = 1.19, 95% CI, 1.11-1.28). In the subgroup analyses by ethnicity, the significant association was found among Caucasians (OR = 1.19, 95% CI, 1.09-1.30) and Hispanics (OR = 1.39, 95% CI, 1.18-1.63), but not in Asians (OR = 1.05, 95% CI, 0.90-1.22). In the subgroup analysis by histology, B-cell ALL risk (OR = 1.29, 95% CI, 1.15-1.44) and B hyperdiploid ALL risk (OR = 1.84, 95% CI, 1.40-2.43) were increased. Our results suggested that CEBPE rs2239633 polymorphism conferred a risk factor of childhood ALL.