scholarly journals Alpha Globin Gene Copy Number Is Associated with Kidney Disease Among Black Individuals

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 2248-2248
Author(s):  
Amy Parker Ruhl ◽  
Neal Jeffries ◽  
Yu Yang ◽  
Rakhi P. Naik ◽  
Lydia H. Pecker ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Kidney Disease ◽  
Copy Number ◽  
Globin Gene ◽  
Gene Copy Number ◽  
Gene Copy ◽  
Alpha Globin ◽  
No Signaling ◽  
End Stage ◽  
Endothelial Nitric Oxide

Introduction: In addition to forming hemoglobin in red blood cells, alpha globin (HBA) has non-erythroid effects and is expressed in vascular endothelial cells where it interacts with endothelial nitric oxide (NO) synthase (eNOS) to limit nitric oxide diffusion across the myoendothelial junction. Reduced expression of HBA or disruption of HBA/eNOS interactions increases endothelial nitric oxide signaling. Humans have 0 to 3 copies of HBA per chromosome and Black individuals have increased variation in HBA allele count. Moreover, Black individuals are more likely to develop end-stage kidney disease (ESKD) and unexplained genetic factors may contribute to racial disparities in kidney disease not attributable to socioeconomic factors. Given that decreased endothelial NO signaling accelerates renal disease in mouse models, we hypothesized that lower HBA gene copy number would be associated with lower risk of kidney disease among Black individuals. Methods: We used droplet digital PCR to measure HBA copy number in Black individuals enrolled in the REasons for Geographic and Racial Differences in Stroke cohort. This national, prospective observational study enrolled 30,239 men and women >45 years of age from the 48 contiguous United States. Prevalent chronic kidney disease (CKD) was defined as eGFR <60 ml/min/1.73m2or urine albumin/creatinine ratio ≥30 mg/g at enrollment. Incident end-stage kidney disease (ESKD) was identified by linkage to the United States Renal Data System. The relative risk (RR) of prevalent CKD was calculated using modified Poisson multivariable regression employing a linear effect of HBA allele count and adjusting for 13 pre-specified genetic, biomedical, and socioeconomic factors. The hazard ratio (HR) for incident ESKD was calculated using Cox proportional hazards regression with the same covariates. Results: HBA copy number ranged from 2 to 6 among 9,918 Black participants (4% with 2 copies, 28% with 3, 67% with 4, and 1% with ≥ 5), with 25% of all participants having CKD at baseline. Participants were followed for a median (25th, 75thpercentile) of 10.1 (5.5, 12.5) years for the development of ESKD, with 2.4% of all participants developing ESKD. As shown in the table, after multivariable adjustment and calculated relative to the most common copy number (4), model-estimated CKD risk was 23% lower among those with 2 copies and 12% lower among those with 3 copies of HBA, while CKD risk was 14% higher among those with 5 or 6 copies of HBA. In addition, relative to 4 copies, ESKD risk was 40% lower among those with 2 copies and 22% lower among those with 3 copies, while the risk of ESKD increased by 29% in those with 5 or 6 copies of HBA. Conclusions: We identified a novel, independent genetic association of HBA copy number with CKD prevalence and ESKD incidence among Black individuals in a national, prospective cohort study in the US. The findings are consistent with our hypothesis that decreased alpha globin gene expression could increase endothelial NO signaling in small renal arteries and confer protection against renovascular injury, while increased alpha globin gene expression couldlimit endothelial NO signaling. These findings suggest that further study of the impact of HBA expression on normal renal physiology and susceptibility to injury is needed. Disclosures Naik: Elsevier: Other: Content Editor.

A Novel β Globin Gene Mutation, Reported As An α Chain Hemoglobin Variant By High Performance Liquid Chromatography (HPLC) & As Sickle Cell Trait On New Born Screening: A case Report

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 954-954
Author(s):  
Kranthi Nandan Seelaboyina ◽  
Jennifer Alison Busse ◽  
Sandeep Malik ◽  
Thomas Moulton
Keyword(s):  
Sickle Cell ◽  
Copy Number ◽  
Sickle Cell Trait ◽  
Globin Gene ◽  
Gene Copy Number ◽  
Gene Copy ◽  
Thalassemia Intermedia ◽  
Exon 2 ◽  
Alpha Globin ◽  
Hemoglobin Variants

Abstract Introduction There are 827 variants of β thalassemia reported to the registry of human hemoglobin variants and thalassemias registry 1. Genetic mutations of β thalassemia are very diverse but can be broadly divided in to non deletion forms and deletion forms. The new mutation is a frame shift insertion in exon 2 of the β globin gene. To the best of our knowledge this mutation has never been described before and presents as a mild form β thalassemia intermedia. Objective To describe the phenotypic presentation of the new β globin variant, due to insertion of 9 nucleotides (AAAGTGCTC) between nucleotides c.207 and c.208. Case report A 22 months-old Hispanic boy who was referred for evaluation of persistent anemia. The new born screening for the child was positive for sickle cell trait. Initial hemoglobin (Hb) was 8.8, hematocrit was 27 and MCV was 65.5, which were decreased. RDW was 25.2, which was increased. Hemoglobin evaluation by acid and alkaline electrophoresis and HPLC revealed a HbS 0%, HbF 6.5% HbA 78.4%, HbA2 4.9% and a Hb variant 10.2%. The interpretation of the results was an α globin variant suggestive of Hb Montefiore and β thalassemia trait. Alpha thalassemia PCR for the 7 most common deletions in the α globin chain was negative. Subsequent α globin gene sequencing revealed no α globin gene mutations. On physical exam there were no bony changes or hepatosplenomegaly. Family History The mother is 29-year-old with HbAA. The father is 39-years-old with the same mutation on beta globin gene analysis. Hb electrophoresis also suggested an α and β globin mutation. Alpha thalassemia PCR was negative and he had a normal α globin gene copy number. At age 19 he had a splenectomy secondary to splenomegaly and hypersplenism. He is consistently anemic with Hb< 9 and MCV < 70. The child has a paternal half brother, who is 21 years old and has similar problems as father. He had a splenectomy at the age of 17 after admission for abdominal pain. The patient has a 5-year-old sibling, who is normal with HbAA and another paternal half sibling reported as no anemia. Discussion Though β thalassemia intermedia is most commonly homozygous or compound heterozygous, less frequently it can be due to single locus mutation. DNA sequencing of the α globin gene of the index case was completely normal and there was normal copy number of the α globin gene in the father. No Hb S was found on Hb electrophoresis. The new mutation adds 9 base pairs to exon 2 and 3 amino acids (Lys-Val-Leu) between amino acid 68 and 69 of the protein. This elongates the beta chain which can lead to instability and precipitation of Hb as well as hemolysis and anemia2. Further studies like short time incubation and pulse chase globin chain synthesis experiments are needed to know the stability of the β globin protein3. In addition, an increase of α globin gene copy number can also be a reason for increasing the severity of β thalassemia trait2. However the α gene copy was normal in the father. Conclusion We present a case of a child with a false positive abnormal newborn screen suggestive of sickle cell trait, as well as a Hb electrophoresis suggestive of an alpha globin mutation. As the father and paternal brother have had a splenectomy in their teen years with noted hepatosplenomegaly, suggestive of increased hemolysis, and the anemia is more severe than usual for β thalassemia trait, this suggests that phenotypically the c.199_207dup variant presents as a mild β thalassemia intermedia. In addition, there does not seem to be any bony abnormalities associated with marrow hyperplasia. As both our patients are heterozygous for this novel mutation with normal α globin gene copy number and alpha globin sequencing, we suspect that elongation of the β globin produces an unstable hemoglobin with a mild β thalassemia intermedia phenotype2. References 1. Databases of human hemoglobin variants and other resources at the globin gene server. Hemoglobin. 25(2):183-93, 2001 May. 2. Galanello R, Cao A. Relationship between genotype and phenotype. Thalassemia intermedia. Annals of the New York Academy of Sciences 1998; 850:325-33. 3. Is hemoglobin instability important in the interaction between hemoglobin E and beta thalassemia? Blood September 15, 1998 vol. 92 no. 6 2141-2146. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Alpha Globin Gene Copy Number Is Associated with Prevalent Chronic Kidney Disease and Incident End-Stage Kidney Disease among Black Americans

2021 ◽  
pp. ASN.2021050653
Author(s):  
A. Parker Ruhl ◽  
Neal Jeffries ◽  
Yu Yang ◽  
Rakhi P. Naik ◽  
Amit Patki ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Kidney Disease ◽  
Copy Number ◽  
Disease Risk ◽  
Globin Gene ◽  
Black Americans ◽  
Community Dwelling ◽  
Gene Copy ◽  
Longitudinal Cohort ◽  
Multivariable Regression

Backgroundα-Globin is expressed in endothelial cells of resistance arteries, where it limits endothelial nitric oxide signaling and enhances α-adrenergic–mediated vasoconstriction. α-Globin gene (HBA) copy number is variable in people of African descent and other populations worldwide. Given the protective effect of nitric oxide in the kidney, we hypothesized that HBA copy number would be associated with kidney disease risk.MethodsCommunity-dwelling Black Americans aged ≥45 years old were enrolled in a national longitudinal cohort from 2003 through 2007. HBA copy number was measured using droplet digital PCR. The prevalence ratio (PR) of CKD and the relative risk (RR) of incident reduced eGFR were calculated using modified Poisson multivariable regression. The hazard ratio (HR) of incident ESKD was calculated using Cox proportional hazards multivariable regression.ResultsAmong 9908 participants, HBA copy number varied from 2 to 6. In analyses adjusted for demographic, clinical, and genetic risk factors, a one-copy increase in HBA was associated with 14% greater prevalence of CKD (PR, 1.14; 95% CI, 1.07 to 1.21; P<0.0001). While HBA copy number was not associated with incident reduced eGFR (RR, 1.06; 95% CI, 0.94 to 1.19; P=0.38), the hazard of incident ESKD was 32% higher for each additional copy of HBA (HR, 1.32; 95% CI, 1.09 to 1.61; P=0.005).ConclusionsIncreasing HBA copy number was associated with a greater prevalence of CKD and incidence of ESKD in a national longitudinal cohort of Black Americans.

scholarly journals HBA Copy Number and Kidney Disease Risk among Black Americans: a Longitudinal Cohort Study

2021 ◽  
Author(s):  
A. Parker Ruhl ◽  
Neal Jeffries ◽  
Yu Yang ◽  
Rakhi P. Naik ◽  
Amit Patki ◽  
...  
Keyword(s):  
Kidney Disease ◽  
Copy Number ◽  
Disease Risk ◽  
Black Americans ◽  
Gene Copy Number ◽  
Community Dwelling ◽  
Gene Copy ◽  
Longitudinal Cohort ◽  
Multivariable Regression ◽  
Prospective Longitudinal

ABSTRACT Background: Alpha globin gene (HBA) copy number is variable among people of African descent. HBA limits endothelial nitric oxide signaling and variation in gene copy number could modify kidney disease risk in this population. Objective: To examine the association of HBA copy number with chronic kidney disease (CKD) and end-stage kidney disease (ESKD). We hypothesized that higher HBA copy number would be associated with greater CKD prevalence and ESKD incidence. Design: Prospective, longitudinal cohort from the REasons for Geographic and Racial Differences in Stroke (REGARDS) study which enrolled participants from 2003 through 2007 and conducted follow-up through June 2014. Data were analyzed from January 2018 through January 2021. Setting: Community-dwelling participants enrolled throughout the contiguous United States Participants: Black Americans age 45 years and older Measurements: HBA copy number was measured using droplet-digital PCR on genomic DNA; copy number ranged from 2 to ≥ 5 copies. The prevalence ratio (PR) of CKD and relative risk (RR) of incident reduced estimated glomerular filtration rate (eGFR) were calculated using modified Poisson multivariable regression employing a log-linear effect of HBA allele count. The hazard ratio (HR) of incident ESKD was calculated using Cox proportional hazards multivariable regression. Results: Among 9,918 participants, HBA gene copy number frequencies were 4%, 28%, 67%, and 1% for 2, 3, 4, and ≥5 copies, respectively. After adjusting for demographic, clinical, and genetic risk factors, each additional copy of HBA was associated with 14% greater prevalence of CKD (PR = 1.14, 95% CI 1.07 to 1.21; P < 0.0001). While there was no significant association with incident reduced eGFR (RR = 1.06, 95% CI 0.94 to 1.18; p = 0.36), the hazard of incident ESKD was 28% higher for each additional copy of HBA (HR = 1.28, 95% CI 1.01 to 1.61; P = 0.04). Limitations: This study did not identify the mechanism by which HBA copy number modifies kidney disease risk. This study focused on Black Americans, a population with a high frequency of the 3.7 kb gene deletion; it is unknown whether HBA modifies kidney disease risk in other populations with the 3.7 kb deletion. Conclusions: Increasing HBA copy number was associated with greater prevalent CKD and incident ESKD in a national longitudinal study of Black Americans. Funding Source: National Institutes of Health

Localization of endothelial nitric oxide synthase in the normal and failing human atrial myocardium

1996 ◽  
Vol 54 ◽  
pp. 786-787
Author(s):  
Chi-Ming Wei ◽  
Margarita Bracamonte ◽  
Shi-Wen Jiang ◽  
Richard C. Daly ◽  
Christopher G.A. McGregor ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Heart Failure ◽  
Nitric Oxide Synthase ◽  
Endothelial Nitric Oxide Synthase ◽  
Cardiac Tissues ◽  
Mammalian Tissues ◽  
End Stage Heart Failure ◽  
End Stage ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide

Nitric oxide (NO) is a potent endothelium-derived relaxing factor which also may modulate cardiomyocyte inotropism and growth via increasing cGMP. While endothelial nitric oxide synthase (eNOS) isoforms have been detected in non-human mammalian tissues, expression and localization of eNOS in the normal and failing human myocardium are poorly defined. Therefore, the present study was designed to investigate eNOS in human cardiac tissues in the presence and absence of congestive heart failure (CHF).Normal and failing atrial tissue were obtained from six cardiac donors and six end-stage heart failure patients undergoing primary cardiac transplantation. ENOS protein expression and localization was investigated utilizing Western blot analysis and immunohistochemical staining with the polyclonal rabbit antibody to eNOS (Transduction Laboratories, Lexington, Kentucky).

scholarly journals Estimating Copy-Number Proportions: The Comeback of Sanger Sequencing

Genes ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 283
Author(s):  
Eyal Seroussi
Keyword(s):  
Copy Number ◽  
Sanger Sequencing ◽  
Cytosine Methylation ◽  
Direct Sequencing ◽  
Information Source ◽  
Gene Copy Number ◽  
Cost Effective ◽  
Gene Copy ◽  
Base Editing ◽  
Recent Developments

Determination of the relative copy numbers of mixed molecular species in nucleic acid samples is often the objective of biological experiments, including Single-Nucleotide Polymorphism (SNP), indel and gene copy-number characterization, and quantification of CRISPR-Cas9 base editing, cytosine methylation, and RNA editing. Standard dye-terminator chromatograms are a widely accessible, cost-effective information source from which copy-number proportions can be inferred. However, the rate of incorporation of dye terminators is dependent on the dye type, the adjacent sequence string, and the secondary structure of the sequenced strand. These variable rates complicate inferences and have driven scientists to resort to complex and costly quantification methods. Because these complex methods introduce their own biases, researchers are rethinking whether rectifying distortions in sequencing trace files and using direct sequencing for quantification will enable comparable accurate assessment. Indeed, recent developments in software tools (e.g., TIDE, ICE, EditR, BEEP and BEAT) indicate that quantification based on direct Sanger sequencing is gaining in scientific acceptance. This commentary reviews the common obstacles in quantification and the latest insights and developments relevant to estimating copy-number proportions based on direct Sanger sequencing, concluding that bidirectional sequencing and sophisticated base calling are the keys to identifying and avoiding sequence distortions.

scholarly journals Nongenotoxic ABCB1 activator tetraphenylphosphonium can contribute to doxorubicin resistance in MX-1 breast cancer cell line

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Raimonda Kubiliute ◽  
Indre Januskeviciene ◽  
Ruta Urbanaviciute ◽  
Kristina Daniunaite ◽  
Monika Drobniene ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Line ◽  
Protein Level ◽  
Copy Number ◽  
Gene Copy Number ◽  
Gene Copy ◽  
Common Mechanism ◽  
Dna Hypomethylation ◽  
Mesenchymal Transition ◽  
Molecular Features

AbstractHyperactivation of ABC transporter ABCB1 and induction of epithelial–mesenchymal transition (EMT) are the most common mechanism of acquired cancer chemoresistance. This study describes possible mechanisms, that might contribute to upregulation of ABCB1 and synergistically boost the acquisition of doxorubicin (DOX) resistance in breast cancer MX-1 cell line. DOX resistance in MX-1 cell line was induced by a stepwise increase of drug concentration or by pretreatment of cells with an ABCB1 transporter activator tetraphenylphosphonium (TPP+) followed by DOX exposure. Transcriptome analysis of derived cells was performed by human gene expression microarrays and by quantitative PCR. Genetic and epigenetic mechanisms of ABCB1 regulation were evaluated by pyrosequencing and gene copy number variation analysis. Gradual activation of canonical EMT transcription factors with later activation of ABCB1 at the transcript level was observed in DOX-only treated cells, while TPP+ exposure induced considerable activation of ABCB1 at both, mRNA and protein level. The changes in ABCB1 mRNA and protein level were related to the promoter DNA hypomethylation and the increase in gene copy number. ABCB1-active cells were highly resistant to DOX and showed morphological and molecular features of EMT. The study suggests that nongenotoxic ABCB1 inducer can possibly accelerate development of DOX resistance.

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