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Hemoglobin May 2020In this study, Hb A variants and their association with α- and β-thalassemia (α- and β-thal) were analyzed. We performed molecular analyses to identify α-thal...
In this study, Hb A variants and their association with α- and β-thalassemia (α- and β-thal) were analyzed. We performed molecular analyses to identify α-thal [- - (Southeast Asian), - - (Thai), -α (rightward) and -α (leftward)] deletions, and Hb Constant Spring (Hb CS; : c.427T>C), Hb A-Melbourne (: c.130G>A), Hb A' (: c.49G>C), Hb A-Lampang (: c.142G>A). β-Thalassemia mutations included codon 17 (A>T) (: c.52A>T), codons 41/42 (-TCTT) (: c.126_129delCTTT), codons 71/72 (+A) (: c.216_217insA) and IVS-I-1 (G>T) (: c.92+1G>T) in 23 samples which had a Hb A variant peak in zone 1 of the capillary electrophoresis (CE) electropherogram. Results showed that 20 patients (87.0%) carried Hb A-Melbourne with seven different genotypes for α- and β-thal, two (8.7%) carried Hb A' and one (4.3%) carried Hb A-Lampang. All three samples doubly heterozygous for Hb A-Melbourne/β-thal had Hb A levels lower than 4.0%, while summation of Hb A and Hb A-Melbourne ranged from 4.9-5.3%, reaching the accepted range (4.0-10.0%) for β-thal trait. Hb A-Melbourne is the most common δ-globin variant in the Thai population. Hb A variant and Hb A levels must be combined in order to diagnose carriers of β-thal. β-Globin haplotype analysis showed an association with a single β-globin haplotype [+ - - - - + +] of Hb A-Melbourne, Hb A' and Hb A-Lampang, indicating that they were of the same origin. We developed a multiplex allele-specific polymerase chain reaction (ASPCR) for simultaneous detection of these three Hb A variants.
Topics: Alleles; Capillary Electrochromatography; DNA Mutational Analysis; Erythrocyte Indices; Genetic Variation; Genotype; Hemoglobin A2; Hemoglobins, Abnormal; Humans; Mutation; Phenotype; Polymerase Chain Reaction; Population Surveillance; Thailand; alpha-Thalassemia; beta-Thalassemia
PubMed: 32482156
DOI: 10.1080/03630269.2020.1770099 -
Clinical Chemistry Mar 2023This is an editorial focusing on the clinical perspective of a long-read sequencing method in the prenatal diagnosis of alpha- and beta-thalassemia, including a...
This is an editorial focusing on the clinical perspective of a long-read sequencing method in the prenatal diagnosis of alpha- and beta-thalassemia, including a comparison between this method and standard PCR-based methods. Though incremental, the increased sensitivity and specificity using long-read sequencing is an important advantage of this methodology in the prenatal diagnostic arena due to false positive or false negative results having greater consequence when a family is making decisions about their pregnancy.
Topics: Pregnancy; Female; Humans; alpha-Thalassemia; Prenatal Diagnosis; beta-Thalassemia; Sequence Analysis, DNA; Sensitivity and Specificity
PubMed: 36648456
DOI: 10.1093/clinchem/hvac223 -
Clinica Chimica Acta; International... Jan 2022Since screening of α-thalassemia carriers by low HbA has a low positive predictive value (PPV), the PPV was as low as 40.97% in our laboratory, other more effective...
BACKGROUND
Since screening of α-thalassemia carriers by low HbA has a low positive predictive value (PPV), the PPV was as low as 40.97% in our laboratory, other more effective screening methods need to be devised. This study aimed at developing a machine learning model by using red blood cell parameters to identify α-thalassemia carriers from low HbA patients.
METHODS
Laboratory data of 1213 patients with low HbA used for modeling was randomly divided into the training set (849 of 1213, 70%) and the internal validation set (364 of 1213, 30%). In addition, an external data set (n = 399) was used for model validation. Fourteen machine learning methods were applied to construct a discriminant model. Performance was evaluated with accuracy, sensitivity, specificity, etc. and compared with 7 previously published discriminant function formulae.
RESULTS
The optimal model was based on random forest with 5 clinical features. The PPV of the model was more than twice the PPV of HbA, and the model had a high negative predictive value (NPV) at the same time. Compared with seven formulae in screening of α-thalassemia carriers, the model had a better accuracy (0.915), specificity (0.967), NPV (0.901), PPV (0.942) and area under the receiver operating characteristic curve (AUC, 0.948) in the independent test set.
CONCLUSION
Use of a random forest-based model enables rapid discrimination of α-thalassemia carriers from low HbA cases.
Topics: Erythrocytes; Hemoglobin A2; Humans; Mass Screening; alpha-Thalassemia; beta-Thalassemia
PubMed: 34883090
DOI: 10.1016/j.cca.2021.12.003 -
Hemoglobin May 2020Hb Westmead (α122(H5)His>Gln) (: c.369C>G) is a common α-globin variant causing α-thalassemia (α-thal) in Mainland China. In this study, we report the hematological...
Hb Westmead (α122(H5)His>Gln) (: c.369C>G) is a common α-globin variant causing α-thalassemia (α-thal) in Mainland China. In this study, we report the hematological characteristics in Hb Westmead carriers in a Chinese population. There were 546 individuals carrying Hb Westmead based on their molecular diagnosis: 514 Hb Westmead heterozygotes and 32 compound heterozygotes for Hb Westmead and α-thal. Compared to common deletional α-thal, Hb Westmead was associated with higher mean corpuscular hemoglobin (Hb) (MCH) values. Compound heterozygotes for Hb Westmead and α-thal showed significantly higher Hb, mean corpuscular volume (MCV) and MCH values than subjects with deletional Hb H disease. When compared to α-thal carriers, compound heterozygotes for Hb Westmead and α-thal showed similar Hb values, but significantly lower MCV and MCH values. Our results indicate that Hb Westmead is a silent nondeletional α-thal, with a deficiency of α-globin chain milder than deletional α-thal, and compound heterozygotes for Hb Westmead/α-thal have a phenotype similar to simple α-thal.
Topics: Alleles; China; DNA Mutational Analysis; Erythrocyte Indices; Genetic Association Studies; Genetic Predisposition to Disease; Hemoglobins, Abnormal; Heterozygote; Homozygote; Humans; Mutation; Phenotype; Polymerase Chain Reaction; Sequence Deletion; alpha-Globins; alpha-Thalassemia
PubMed: 32436451
DOI: 10.1080/03630269.2020.1768109 -
Pediatric Hematology and Oncology Sep 2022Hemoglobin H (Hb H) disease is a subtype of α-thalassemia caused by deletional and/or non-deletional mutations in three alpha-globin genes in which the various...
Hemoglobin H (Hb H) disease is a subtype of α-thalassemia caused by deletional and/or non-deletional mutations in three alpha-globin genes in which the various genotypes determine the disease severity. This study was aimed to investigate the frequency of alpha gene mutations and genotypes and their correlation with hematological and clinical characteristics in Iran. Among 202 patients diagnosed with Hb H disease through a national study in Iran according to standard methods, we had access to the hematologic and clinical findings and genetic data of 101 patients in whom genetic study was performed. Genomic DNA from peripheral blood was extracted and analyzed for identification of α-globin gene mutations using Multiplex Gap Polymerase Chain Reaction, Reverse Hybridization Assay, and finally Direct DNA Sequencing method. Twenty-one different mutations and thirty genotypes were detected in 101 patients with Hb H disease. In total, 39 patients (38.6%) were deletional and 62 patients (61.4%) were non-deletional type of the disease. The mutation was highly prevalent in almost half of the patients (56.4%). Among various genotypes, -/-a (29.7%) and -α/-α (6.9%) were the most prevalent genotypes found in the studied group. Patients with non-deletional type presented with more severe hematological and clinical findings. Hb H percentage and serum ferritin levels were significantly higher in non-deletional patients in comparison to the deletional group ( < 0.05). 12 (11.9%) and 40 (39.6%) out of 101 patients were on regular and occasional transfusions, respectively. 83% of those with regular transfusion belonged to the non-deletional group. Among transfusion-dependent patients, -/αα and α/-α were the most common genotypes. In this study, two patients with -α/αα and -/α genotypes experienced thrombotic events. This study indicated that although non-deletional genotypes of Hb H disease were responsible for more clinical severity of the disease, due to the presence of severe phenotypes even in deletional types, no definite correlation was found between genotype and phenotype.
Topics: Genotype; Humans; Iran; Mutation; Phenotype; alpha-Globins; alpha-Thalassemia
PubMed: 34951342
DOI: 10.1080/08880018.2021.2017529 -
Journal of Clinical Laboratory Analysis Nov 2016α-Thalassemia is a benign condition that is often present in patients with diabetes mellitus. Here, we evaluated the effects of different genotypes α-thalassemia on...
BACKGROUND
α-Thalassemia is a benign condition that is often present in patients with diabetes mellitus. Here, we evaluated the effects of different genotypes α-thalassemia on HbA measurement.
METHODS
A total of 189 samples from nondiabetic patients were analyzed. HbA analysis was performed by ion-exchange high-performance liquid chromatography, boronate affinity HPLC, immunoassay, and capillary electrophoresis. Fasting glucose, fructosamin, and HbA were also performed. All samples were confirmed by genotyping for thalassemia.
RESULTS
In patients with two or three functional α-genes, HbA values were not significantly different from those of controls (P > 0.05); however, in individuals with α-thalassemia with one functional α-gene (i.e., HbH disease), HbA levels were significantly different from those of controls (P < 0.01). HbA values were significantly lower in individuals with HbH disease than in control individuals and patients in the other two α-thalassemia groups. For patients with HbH disease, there were no significant differences in the four HbA measurement systems (P > 0.05).
CONCLUSIONS
In this study, HbA values in samples from individuals with two or three functional α-genes basically reflected the normal mean blood glucose level, while those in samples from individuals with one functional α-gene did not.
Topics: Adult; Chromatography, High Pressure Liquid; Fasting; Female; Ferritins; Fructosamine; Glycated Hemoglobin; Humans; Male; Young Adult; alpha-Thalassemia
PubMed: 27184351
DOI: 10.1002/jcla.21983 -
Journal of Clinical Laboratory Analysis Feb 2019There is paucity of data on the influence of alpha thalassemia on the clinical and laboratory parameters among Nigerian sickle cell anemia (SCA) patients. This study...
BACKGROUND
There is paucity of data on the influence of alpha thalassemia on the clinical and laboratory parameters among Nigerian sickle cell anemia (SCA) patients. This study aimed to determine the prevalence of alpha thalassemia and the influence of alpha thalassemia on laboratory parameters and clinical manifestations in a group of young Nigerian SCA patients.
METHODS
This was a cross-sectional retrospective study conducted on 100 patients with SCA and 63 controls. The diagnosis of SCA was confirmed by DNA studies. Alpha thalassemia genotyping was performed by multiplex gap-PCR method. Laboratory parameters including complete blood count, hemoglobin quantitation, serum lactate dehydrogenase (LDH), and bilirubin were determined with standard techniques.
RESULTS
Alpha thalassemia was found in 41 (41.0%) patients compared to 24 (38.1%) controls (P = 0.744), and all were due to the 3.7 κb α-globin gene deletions. Alpha thalassemia was associated with more frequent bone pain crisis, higher hemoglobin concentration, red blood cell count, and HbA level among the patients. On the contrary, patients with alpha thalassemia had lower mean corpuscular volume, mean corpuscular hemoglobin, and white blood cell count (WBC) (P ˂ 0.05). There were 6 (6.0%) patients with leg ulcers, and none of them had alpha thalassemia, P = 0.04.
CONCLUSION
This study confirms that coexistence of alpha thalassemia with SCA significantly influences both the clinical and laboratory manifestations of young Nigerian SCA patients. The coexistence of this genetic modifier is associated with increased bone pain crisis and protects against sickle leg ulcers among the patients.
Topics: Adolescent; Adult; Anemia, Sickle Cell; Blood Cell Count; Child; Child, Preschool; Cross-Sectional Studies; Female; Gene Frequency; Hemoglobins; Humans; Male; Nigeria; Polymerase Chain Reaction; Retrospective Studies; Young Adult; alpha-Thalassemia
PubMed: 30129219
DOI: 10.1002/jcla.22656 -
Pediatric Blood & Cancer Jan 2015Hemoglobinopathies are the most common reported monogenic disorders worldwide. It is well established that Mediterranean and Arab countries are high risk areas for...
BACKGROUND
Hemoglobinopathies are the most common reported monogenic disorders worldwide. It is well established that Mediterranean and Arab countries are high risk areas for thalassemia in general, and for alpha thalassemia in particular. Reports of alpha thalassemia gene mutations from the Lebanese population are limited.
PROCEDURE
We investigated the spectrum of alpha thalassemia mutations in a sample of 70 unrelated Lebanese families. Six different mutations of alpha thalassemia gene were identified.
RESULTS
The most prevalent mutations were the single gene deletion -α(3.7) (43%) and the non-gene deletion α2 IVS1 [-5nt] (37%). The double deletional determinant -(MED) was detected only in 14% of thalassemic chromosomes.
CONCLUSION
We determined the mutational spectrum of alpha thalassemia which might be used in the future for molecular investigations of the disease in susceptible patients in our population.
Topics: Family; Female; Follow-Up Studies; Gene Frequency; Humans; Lebanon; Male; Mutation; Polymerase Chain Reaction; Prognosis; Retrospective Studies; alpha-Globins; alpha-Thalassemia
PubMed: 25284125
DOI: 10.1002/pbc.25242 -
Human Genomics Aug 2023Thalassemia is an extremely prevalent monogenic inherited blood disorder in southern China. It is important to comprehensively understand the molecular spectrum of...
BACKGROUND
Thalassemia is an extremely prevalent monogenic inherited blood disorder in southern China. It is important to comprehensively understand the molecular spectrum of thalassemia in an area with such a high prevalence of thalassemia before taking appropriate actions for the prevention and treatment of this disorder. Herein, we explored the clinical feasibility of using next-generation sequencing (NGS) for large-scale population screening to illustrate the prevalence and spectrum of thalassemia in Southern Jiangxi.
METHODS
Blood samples collected from 136,312 residents of reproductive age in Southern Jiangxi were characterized for thalassemia by NGS. A retrospective analysis was then conducted on blood samples determined to be positive for thalassemia.
RESULTS
In total, 19,827 (14.545%) subjects were diagnosed as thalassemia carriers, and the thalassemia prevalence rate significantly varied by geographical region (p < 0.001). A total of 40 α-thalassemia genotypes including 21 rare genotypes were identified, with -@-/αα being the most prevalent genotype. 42 β-thalassemia genotypes including 27 rare genotypes were identified, with the most common mutation IVS II-654 C > T accounting for 35.257% of these β-thalassemia genotypes. Furthermore, 74 genotypes were identified among 608 individuals with combined α- and β-thalassemia. Notably, most individuals with rare thalassemia mutations had mildly abnormal hematologic parameters including microcytic hypochromia.
CONCLUSIONS
Our findings demonstrate the great heterogeneity and diverse spectrum of thalassemia in Southern Jiangxi, emphasizing the importance and necessity of persistent prevention and control of thalassemia in this region. Additionally, our findings further suggest that NGS can effectively identify rare mutations and reduce the misdiagnosis rate of thalassemia.
Topics: Humans; beta-Thalassemia; Retrospective Studies; alpha-Thalassemia; High-Throughput Nucleotide Sequencing; China
PubMed: 37592328
DOI: 10.1186/s40246-023-00520-5 -
Scientific Reports Jun 2023α-Thalassaemia is an inherited haemoglobin disorder that results from the defective synthesis of α-globin protein. Couples whom both carry the α-thalassaemia 1 gene...
α-Thalassaemia is an inherited haemoglobin disorder that results from the defective synthesis of α-globin protein. Couples whom both carry the α-thalassaemia 1 gene are at risk of having a foetus with the most severe thalassaemia, Hb Bart's hydrops fetalis, with a risk of maternal mortality. However, haematological parameters alone cannot distinguish between a α-thalassaemia 1 carrier and a homozygous α-thalassaemia 2, in which one α-globin gene has been deleted on each chromosome. A rapid and accurate molecular detection assay is essential for prevention of the disease in populations where α-thalassaemia 1 is common. Multiplex Gap-PCR analysis is widely used for diagnosis of α-thalassaemia. However, the technique requires a thermocycler and post-amplification processing, which limits its application in primary care or in rural areas in developing countries. Loop mediated isothermal amplification (LAMP) amplifies target DNA at a constant temperature and does not require a thermocycler. This study developed a colorimetric Gap-LAMP using malachite green to allow naked eye visualization of two deletional α-thalassaemia 1 commonly found in Asian populations, the Southeast Asian type (--) and the Thai type (--) deletions. The Gap-LAMP was performed on DNA samples from 410 individuals carrying various α-thalassaemia gene defects with 100% concordance with conventional Gap-PCR analysis. This method eliminates post-amplification processing or the use of expensive sophisticated equipment and allows screening large populations for the prevention and control of α-thalassaemia.
Topics: Humans; Female; alpha-Thalassemia; Colorimetry; Hemoglobinopathies; Hydrops Fetalis
PubMed: 37311778
DOI: 10.1038/s41598-023-36676-2