RESUMEN
BACKGROUND: Hemoglobin (Hb) Hammersmith is a rare form of unstable ß-chain hemoglobinopathy causing hemolytic anemia. This rare event led to a more serious transfusion-dependent phenotype in a patient. It was successfully cured by haploidentical hematopoietic stem cell transplantation (HSCT). METHODS AND RESULTS: A 9-year-old mainland Chinese male with a history of neonatal unconjugated hyperbilirubinemia was diagnosed to have hemoglobin (Hb) Hammersmith. He required regular blood transfusion but was unable to be transfused to desired parameters for 8 years prior to transplant due to social and geographical reasons. He subsequently developed marrow hyperplasia and progressive splenomegaly (down to umbilicus level), suggestive of extramedullary hematopoiesis. Eventually, the family came to Hong Kong and complied to a more intensive transfusion regimen and preconditioning chemotherapy 3 months prior to transplant. He underwent haploidentical HSCT using paternal TCRαß/CD45RA-depleted graft but suffered from graft rejection, despite splenic irradiation for massive splenomegaly. It was successfully salvaged with second HSCT with unmanipulated graft from the same donor with additional serotherapy and donor lymphocyte infusions. CONCLUSION: Allogenic haploidentical HSCT for hemoglobin Hammersmith is feasible but adequate immunosuppression during conditioning is crucial. Precise adoptive cell therapy can promote durable engraftment.
Asunto(s)
Trasplante de Células Madre Hematopoyéticas , Esplenomegalia , Reacción a la Transfusión , Pueblo Asiatico , Niño , Haploidia , Hemoglobinas Anormales , Humanos , Donadores Vivos , Transfusión de Linfocitos , Linfocitos , Masculino , Esplenomegalia/etiología , Esplenomegalia/terapiaRESUMEN
Haemoglobin H (HbH) disease is a type of non-transfusion-dependent thalassaemia. This cross-sectional study aimed at determining the prevalence and severity of liver iron overload and liver fibrosis in patients with HbH disease. Risk factors for advanced liver fibrosis were also identified. A total of 80 patients were evaluated [median (range) age 53 (24-79) years, male 34%, non-deletional HbH disease 24%]. Patients underwent 'observed' T2-weighted magnetic resonance imaging examination for liver iron concentration (LIC) quantification, and transient elastography for liver stiffness measurement (LSM) and fibrosis staging. In all, 25 patients (31%) had moderate-to-severe liver iron overload (LIC ≥7 mg/g dry weight). The median LIC was higher in non-deletional than in deletional HbH disease (7·8 vs. 2.9 mg/g dry weight, P = 0·002). In all, 16 patients (20%) had advanced liver fibrosis (LSM >7.9 kPa) and seven (9%) out of them had probable cirrhosis (LSM >11.9 kPa). LSM positively correlated with age (R = 0·24, P = 0·03), serum ferritin (R = 0·36, P = 0·001) and LIC (R = 0·28, P = 0·01). In multivariable regression, age ≥65 years [odds ratio (OR) 4·97, 95% confidence interval (CI) 1·52-17·50; P = 0·047] and moderate-to-severe liver iron overload (OR 3·47, 95% CI 1·01-12·14; P = 0·01) were independently associated with advanced liver fibrosis. The findings suggest that regular screening for liver complications should be considered in the management of HbH disease.
Asunto(s)
Hepatopatías/etiología , Talasemia alfa/complicaciones , Adulto , Anciano , Estudios Transversales , Femenino , Humanos , Hierro/análisis , Sobrecarga de Hierro/etiología , Sobrecarga de Hierro/patología , Cirrosis Hepática/etiología , Cirrosis Hepática/patología , Hepatopatías/patología , Masculino , Persona de Mediana Edad , Adulto Joven , Talasemia alfa/patologíaRESUMEN
Prenatal screening of ß-thalassemia (ß-thal) carriers is based on the hallmark phenotype of microcytosis and raised Hb A2. The unanticipated birth of ß-thal major (ß-TM) offspring to ß-thal carriers who were misdiagnosed during prenatal screening have been reported. A subset of these resulted from the masked phenotype due to the coinheritance of HBD variants. In a broader sense, the causes of reduced Hb A2 in thalassemia screening, the prevalence and spectrum of HBD variants in Hong Kong remain to be characterized. Over a 13-month period, a total of 2982 samples were referred for thalassemia screening. Surplus samples with reduced Hb A2 levels (2.0%) were evaluated. HBD variations were assessed by direct sequencing. Sixty-six samples were tested. Hb H disease, HBD variants, α-thalassemia (α-thal) trait and iron deficiency were detected in 40 (60.6%), 12 (18.2%), eight (12.1%) and seven (10.6%) samples, respectively. Seven samples carried more than one of the mentioned conditions. The cause remained elusive in seven samples. Thirteen HBD variants were detected and two were recurrent, including HBD: c.-127T>C [-77 (T>C)] and HBD: c.314G>A (Hb Chori-Burnaby). A novel nonsense variant HBD: c.262C>T [codon 87 (C>T)] was detected in cis with HBD: c.-127T>C. Overall, the prevalence of HBD variants was 0.4%. This study advanced our understanding of the causes of reduced Hb A2 in clinical practice and identified hereditary disorders of α- and δ-globin genes as the prevailing causes. It established the landscape of HBD variations in our locality and highlighted the pitfall of phenotypic screening of ß-thal carriers.
Asunto(s)
Talasemia alfa , Talasemia beta , Globinas delta , Hemoglobina A2/genética , Heterocigoto , Hong Kong/epidemiología , Humanos , Mutación , Talasemia alfa/diagnóstico , Talasemia alfa/epidemiología , Talasemia alfa/genética , Talasemia beta/diagnóstico , Talasemia beta/epidemiología , Talasemia beta/genética , Globinas delta/genéticaRESUMEN
RUNX1 encodes a Runt-related transcription factor that is critical for hematopoiesis. In this study, through a combinatorial molecular approach, we characterized a novel t(5;21)(q13;q22) translocation involving RUNX1 that was acquired during the progression of myelodysplastic syndrome to acute myeloid leukemia (AML) in a pediatric patient. We found that this translocation did not generate RUNX1 fusion but aberrantly upregulated RUNX1. This upregulation was attributed to the disruption of long-range chromatin interactions between the RUNX1 P2 promoter and a silencer in the first intron of the gene. Characterization of the silencer revealed a role of SNAG repressors and their corepressor LSD1/KDM1A in mediating the effect. Our findings suggest that chromosomal rearrangements may activate RUNX1 by perturbing its transcriptional control to contribute to AML pathogenesis, in keeping with an emerging oncogenic role of RUNX1 in leukemia.
Asunto(s)
Cromosomas Humanos Par 11/genética , Subunidad alfa 2 del Factor de Unión al Sitio Principal/genética , Leucemia Mieloide Aguda/genética , Regulación hacia Arriba , Preescolar , Cromosomas Humanos Par 21/genética , Regulación Leucémica de la Expresión Génica , Humanos , Masculino , Regiones Promotoras Genéticas , Translocación GenéticaRESUMEN
We report a novel HBB: c.114G>C mutation in a Chinese family. This mutation resulted in a ß37(C3)TrpâCys amino acid substitution and was synonymous with Hb Kent, a hemoglobin (Hb) variant that was reported exclusively in patients of European descent. Though Hb Kent has a normal oxygen affinity and molecular stability, it has a characteristic dual variant appearance on cellulose acetate electrophoresis (CAE) and high performance liquid chromatography (HPLC) caused by the posttranslational modification of cysteine. We also report the phenotypic expression of this variant when coinherited with the Southeast Asian (- -SEA) double α-globin gene deletion.
Asunto(s)
Hemoglobinas Anormales/genética , Mutación Missense , Adulto , Sustitución de Aminoácidos , Pueblo Asiatico , China , Familia , Femenino , Hemoglobinas Anormales/metabolismo , Humanos , MasculinoRESUMEN
Genetic association studies showed that Hb F is under the influence of major quantitative trait loci (QTL) in ß-thalassemia (ß-thal) carriers. Single nucleotide polymorphisms (SNPs) at three major QTLs, BCL11A, HBS1L-MYB intergenic region and XmnI-HBG2 were individually validated in univariate models. However, their relative effect sizes on Hb F regulation are unknown. We genotyped 99 Chinese ß-thal carriers for the three major QTLs and performed genetic association studies using three different statistical models, including mass univariate analysis, multivariate linear regression and partial least square regression structural equation modeling (PLS-SEM). Performances of the three models were compared and effect sizes of the three QTLs in a multivariate model were assessed. Traditional mass univariate analysis and multivariate linear regression showed limited statistical power in our small cohort and the latter was constrained by multicollinearity. Partial least structural equation modeling showed significant positive associations of each QTL (p <0.05) with Hb F regulation, together explained 34.4% of variance. The HBS1L-MYB intergenic region polymorphism (HMIP) demonstrated the highest effect on Hb F prediction with effect size f2 0.294. PLS-SEM offered a statistically powerful multivariate model for multi-locus genetic association studies. We reproduced findings of previous studies with a much smaller cohort and demonstrated HMIP as the strongest regulator of Hb F in Chinese ß-thal carriers.
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Hemoglobina Fetal/metabolismo , Heterocigoto , Sitios de Carácter Cuantitativo , Talasemia beta/genética , Adulto , Pueblo Asiatico , ADN Intergénico/genética , Femenino , Proteínas de Unión al GTP/genética , Proteínas HSP70 de Choque Térmico/genética , Humanos , Masculino , Modelos Estadísticos , Factores de Elongación de Péptidos/genética , Polimorfismo de Nucleótido Simple , Proteínas Proto-Oncogénicas c-myb/genéticaAsunto(s)
Proteínas Sanguíneas/genética , Epidemiología Molecular , Mutación , Adolescente , Adulto , Anciano , China/epidemiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Proteína S/genética , Deficiencia de Proteína S/epidemiología , Deficiencia de Proteína S/genética , Adulto JovenAsunto(s)
Neoplasias de la Médula Ósea , Hipertrigliceridemia , Tomografía Computarizada por Rayos X , Xantomatosis , Neoplasias de la Médula Ósea/sangre , Neoplasias de la Médula Ósea/diagnóstico por imagen , Humanos , Hipertrigliceridemia/sangre , Hipertrigliceridemia/diagnóstico por imagen , Masculino , Persona de Mediana Edad , Xantomatosis/sangre , Xantomatosis/diagnóstico por imagenRESUMEN
The bulk of the human genome (~98%) is comprised of non-coding sequences. Cis-regulatory elements (CREs) are non-coding DNA sequences that contain binding sites for transcriptional regulators to modulate gene expression. Alterations of CREs have been implicated in various diseases including cancer. While promoters and enhancers have been the primary CREs for studying gene regulation, very little is known about the role of silencer, which is another type of CRE that mediates gene repression. Originally identified as an adaptive immunity system in prokaryotes, CRISPR/Cas9 has been exploited to be a powerful tool for eukaryotic genome editing. Here, we present the use of this technique to delete an intronic silencer in the human RUNX1 gene and investigate the impacts on gene expression in OCI-AML3 leukemic cells. Our approach relies on electroporation-mediated delivery of two preassembled Cas9/guide RNA (gRNA) ribonucleoprotein (RNP) complexes to create two double-strand breaks (DSBs) that flank the silencer. Deletions can be readily screened by fragment analysis. Expression analyses of different mRNAs transcribed from alternative promoters help evaluate promoter-dependent effects. This strategy can be used to study other CREs and is particularly suitable for hematopoietic cells, which are often difficult to transfect with plasmid-based methods. The use of a plasmid- and virus-free strategy allows simple and fast assessments of gene regulatory functions.
Asunto(s)
Sistemas CRISPR-Cas , Subunidad alfa 2 del Factor de Unión al Sitio Principal/metabolismo , Leucemia Mieloide Aguda/metabolismo , Animales , Línea Celular Tumoral , Subunidad alfa 2 del Factor de Unión al Sitio Principal/genética , Edición Génica/métodos , Regulación Neoplásica de la Expresión Génica , Silenciador del Gen , Humanos , Ratones , ARN Guía de Kinetoplastida/genética , Ribonucleoproteínas/metabolismoRESUMEN
BACKGROUND: Previous studies in Western countries demonstrated BRAF V600E mutation only in a small subset of multiple myeloma (MM) patients. However, the prevalence and clinicopathologic significances of this mutation remain unclear in Chinese MM patients. PATIENTS AND METHODS: We studied diagnostic bone marrow samples from 205 Chinese MM patients by allele-specific PCR to detect BRAF V600E mutation and by high-resolution melting assay to detect KRAS and NRAS mutations. The mutations were confirmed by independent assays. RESULTS: BRAF V600E mutation was found in 9.3% of the cases, the highest prevalence hitherto reported. In addition, the mutation was significantly associated with hypercalcemia and a male predominance but not with aggressive extramedullary diseases or a high serum creatinine level as reported in Western studies. Importantly, BRAF V600E mutation was an adverse prognostic factor for overall survival in younger MM patients by subgroup analysis. Concurrent analysis of RAS mutations highlighted differential alteration spectrum of RAS signaling between Chinese and Western MM, which may suggest a unique myeloma-related genetic profile in Chinese patients. CONCLUSION: Our study revealed a higher prevalence of BRAF V600E mutation in Chinese MM patients. The associated prognostic impacts on younger patients could be beneficial to risk stratification and potential application of BRAF-targeted therapies in Chinese MM management. This is the first large-scale study revealing the prevalence and clinicopathologic significances of BRAF V600E mutation in Chinese myeloma.