Journal: Blood cells, molecules & diseases
Gaucher disease (GD) is characterized by accumulation of glucosylceramide in lysosomes due to mutations in the GBA1 gene encoding the lysosomal hydrolase β-glucocerebrosidase (GCase). The disease has a broad spectrum of phenotypes, which were divided into three different Types; Type 1 GD is not associated with primary neurological disease while Types 2 and 3 are associated with central nervous system disease. GCase molecules are synthesized on endoplasmic reticulum (ER)-bound polyribosomes, translocated into the ER and following modifications and correct folding, shuttle to the lysosomes. Mutant GCase molecules, which fail to fold correctly, undergo ER associated degradation (ERAD) in the proteasomes, the degree of which is one of the factors that determine GD severity. Several pharmacological chaperones have already been shown to assist correct folding of mutant GCase molecules in the ER, thus facilitating their trafficking to the lysosomes. Ambroxol, a known expectorant, is one such chaperone. Here we show that ambroxol increases both the lysosomal fraction and the enzymatic activity of several mutant GCase variants in skin fibroblasts derived from Type 1 and Type 2 GD patients.
BACKGROUND: The impact of obesity on hematopoietic stem cell transplantation (HSCT) outcome remains controversial and has been considered a relative contraindication for the procedure. We investigated the influence of Body Mass Index (BMI) on the clinical course of adults undergoing an ambulatory HSCT after a non-myeloablative conditioning regimen. METHODS: Adults with hematologic diseases undergoing an autologous or allogeneic HSCT after reduced intensity conditioning (RIC) and supported exclusively with enteral nutrition (EN) were studied. BMI and body fat were sequentially determined. Patients were divided into three BMI subgroups: underweight; normal, and overweight/obese. RESULTS: Seventy-seven patients with a median follow-up of 21months were evaluated. Fourteen (18.2%) were underweight, 21 (27.3%) had a normal weight, and 42 (54.5%) were overweight/obese. A significant weight loss was observed among all three weight groups after HSCT (P=0.014). No correlation was found between time to engraftment and BMI (P=0.91), serum albumin (P=0.387), and fasting glucose (P=0.64), nor between BMI and acute (P=0.456) or chronic (P=0.209) graft versus host disease (GVHD). On multivariate analysis a higher overall survival (OS) was documented for obese patients (P=0.037). DISCUSSION: A BMI >30/kg/m(2) was independently associated with a higher survival rate after HSCT. Obese patients should not be excluded as transplant candidates based only on this parameter.
Approximately 80% of α-thalassemia mutations are deletions in the α-globin cluster on chromosome 16 and about 10% of β-thalassemia mutations are deletions in the β-globin gene cluster on chromosome 11. Larger deletions involving the β-globin gene cluster lead to (δβ)-, (γδβ)-, (εγδβ)-thalassemia, or hereditary persistence of fetal hemoglobin (HPFH). Array comparative genomic hybridization (CGH) was applied to screen for deletions in the α- and β-globin gene clusters not detected by routine gap-PCR. In total, in 13 patients with hypochromia and inclusion bodies (IBs) the α-globin gene cluster was analyzed and in 13 patients with increased fetal hemoglobin levels with or without hypochromia the β-globin gene cluster was examined. All samples were subsequently investigated by multiplex ligation-dependent probe amplification (MLPA). In 9 out of 13 patients deletions of the α-globin gene cluster were identified; 5 of these deletions remove the entire α-globin cluster and extend to the telomere. Additional sequencing of the remaining 4 patients revealed polyadenylation mutation in 1 of them. 7 deletions were identified in the β-globin gene cluster in 13 patients. Additional sequencing of the remaining 6 patients revealed mutations in one of the γ-globin gene promoters in 3 of them and a KLF1-mutation in 1 of them. Array CGH is a reliable method to screen for deletions in thalassemia and hemoglobinopathy. The method offers the advantage of a high resolution with the possibility to characterize breakpoints on sequence level.
Alpha thalassemia (α-thal) is one of the most common genetic disorders in the world. It is characterized by the absence or reduced expression of α-globin genes. The frequency of α-thal mutations in the province of Hatay in South Turkey is unknown. Therefore, in the present study, we aimed to investigate the spectrum of α-thal mutations in this province. Three hundred and nine patients were tested for α-thal mutations by using reverse dot blot hybridization technique and nine different mutations were detected in 97 of them. Among the 9 different mutations found, the most frequent mutations were the -α(3.7) (43.81%), -α2(-5nt) (6.70%), - -(MED) (5.67%) and α2(Poly A2) (2.57%). In the present study, - -(FIL) mutation was detected in a patient for the first time in Turkey. Our results indicated that α-thal mutations are highly heterogeneous and -α(3.7) is the most prevalent mutation in Hatay province of South Turkey. In addition, - -(FIL) mutation was detected in a patient for the first time in Turkey. This new finding may contribute to the establishment of a national mutation database and genetic counseling.
UGT1A1 enzyme defects are responsible of both Gilbert syndrome (GS) and Crigler-Najjar syndrome (CNS). GS depends on a variant TATAA element (which contains two extra TA nucleotides as compared to the wild type genotype) in the UGT1A1 gene promoter resulting in a reduced gene expression. On the contrary, CNS forms are classified in two types depending on serum total bilirubin concentrations (STBC): the more severe (CNS-I) is characterized by high levels of STBC (342-684μmol/L), due to total deficiency of the UGT1A1 enzyme, while the milder one, namely CNS-II, is characterized by partial UGT1A1 deficiency with STBC ranging from 103 to 342μmol/L. GS and CNS are caused by genetic lesions involving a complex locus encoding the UGT1A1 gene. The present report provides an update of all reported UGT1A1 gene mutations associated to GS and CNS.
BACKGROUND: β-Thalassemia is a disorder caused by mutations at the hemoglobin β-gene (HBB) locus. Its most important manifestation, the major form, is characterized by severe hypochromic and hemolytic anemia and is inherited in an autosomal recessive mode. In Gaza Strip, Palestine 0.02% of the population has been identified as β-thalassemia major. DESIGN AND METHODS: An assessment of mutations was performed in 49 transfusion dependent patients with β-thalassemia major and in 176 β-thalassemia carriers diagnosed with a mean erythrocyte cell volume (MCV) <80fl and a proportion of HbA(2)>3.5%. In addition 39 individuals suspicious for β-thalassemia carrier status due to a reduced MCV (<80fl) but a normal HBA(2) were screened. RESULTS: By screening with three hybridization assays a proportion of 80% of the thalassemic chromosomes from patients and carriers was identified to carry five different mutations of the hemoglobin (Hb) β-gene. Subsequent DNA sequencing confirmed these and revealed further 9% of the chromosomes to be affected by other mutations. In addition six chromosomes from suspicious carriers were detected to carry β-thalassemia mutations. Of the 15 different HBB mutations identified the variant IVS-I-110 G>A was the most frequent mutation identified in 34% of the thalassemic chromosomes, followed by IVS-I-1 G>A, IVS-I-6 T>C, Codon 39 C>T, and Codon 37 G>A. Three novel HBB variants were discovered by direct sequencing of the gene: 5' UTR-50 (-/G), 5' UTR-43 C>T, and IVS-II-26 T>G. CONCLUSIONS: The spectrum of HBB mutations described is of the Mediterranean type whereby the allele frequencies of the most common mutations differ from those, which were previously described for the population of the Gaza Strip and other Palestinian populations. The data presented may promote the introduction of molecular testing to the Palestinian premarital screening program for β-thalassemia in Gaza Strip, which will improve the screening protocol and genetic counseling in the future.
Dexpramipexole, an orally bioavailable small molecule previously under clinical development in amyotrophic lateral sclerosis, was observed during routine safety hematology monitoring to demonstrate pronounced, dose- and time-dependent eosinophil-lowering effects, with minor reductions on other leukocyte counts. Analysis of hematology lab values across two double-blind, randomized placebo-controlled clinical trials at total daily doses ranging from 50mg to 300mg demonstrated that dexpramipexole consistently and markedly lowered peripheral blood eosinophils. This effect developed after 1month on treatment, required 3-4months to reach its maximum, remained constant throughout treatment, and partially recovered to baseline levels upon drug withdrawal. All doses tested were well tolerated. The overall adverse event rate was similar for dexpramipexole and placebo, and notably with no increase in infection-related adverse events associated with eosinophil-lowering effects. Given the reliance on and insufficiency of off-label chronic corticosteroid therapy for hypereosinophilic syndromes and other eosinophilic-associated diseases (EADs), a need exists for less toxic, more effective, targeted therapeutic alternatives. Further clinical studies are underway to assess the eosinophil-lowering effect of dexpramipexole in the peripheral blood and target tissues of EAD patients and whether such reductions, if observed, produce clinically important benefits.
Identifying sickle cell disease patients at high risk of complications could lead to personalized treatment and better prognosis but despite many advances prediction of the clinical course of these patients remains elusive. We propose a system-type approach to discover profiles of multiple, common biomarkers that correlate with morbidity and mortality in sickle cell disease. We used cluster analysis to discover 17 signatures of 17 common circulating biomarkers in 2320 participants of the Cooperative Study of Sickle Cell Disease, and evaluated the association of these signatures with risk for stroke, pain, leg ulceration, acute chest syndrome, avascular necrosis, seizure, death, and trend of fetal hemoglobin and hemolysis using longitudinally collected data. The analysis shows that some of the signatures are associated with reduced risk for complications, while others are associated with increased risk for complications. We also show that these signatures repeat in two more contemporary studies of sickle cell disease and correlate with recently discovered biomarkers of pulmonary vascular disease. With replication and further study, these biomarker signatures could become an important and affordable precision medicine tool to aid treatment and management of the disease.
The single base molecular substitution characterizing sickle cell haemoglobin, β6glu→val, might be expected to result in predictable haematological and clinical features. However, the disease manifests remarkable diversity believed to reflect the interaction with other genetic and environmental factors. Some of the genetic modifiers include the beta globin haplotypes, alpha thalassaemia, factors influencing the persistence of fetal haemoglobin and the effects of the environment are addressed in this review. It is concluded that much of the genetic data present conflicting results. Environmental factors such as climate and infections, and psychological, educational and social support mechanisms also influence expression of the disease. These interactions illustrate how the expression of a ‘single gene’ disorder may be influenced by a variety of other genetic and environmental factors.
α-Thalassemia is an inherited, autosomal recessive, disorder characterized by a microcytic hypochromic anemia. It is one of the most common monogenic gene disorders in the world population. The clinical severity varies from almost asymptomatic, to mild microcytic hypochromic, and to a lethal hemolytic condition, called Hb Bart’s Hydrops Foetalis Syndrome. The molecular basis are usually deletions and less frequently, point mutations affecting the expression of one or more of the duplicated α-genes. The clinical variation and increase in disease severity is directly related to the decreased expression of one, two, three or four copies of the α-globin genes. Deletions and point mutations in the α-globin genes and their regulatory elements have been studied extensively in carriers and patients and these studies have given insight into the α-globin genes are regulated. By looking at naturally occurring deletions and point mutations, our knowledge of globin-gene regulation and expression will continue to increase and will lead to new targets of therapy.