Uncommon Combination of Hemoglobin Jax and Hemoglobin Constant Spring Leading to Microcytic Anemia.

BACKGROUND Thalassemia and hemoglobin (Hb) variants are the most common hereditary red blood cell disorders worldwide. Alpha-thalassemia and alpha-globin variants are caused by mutations of the alpha-globin genes (HBA2 and HBA1), resulting in impaired alpha-globin production and structurally abnormal globin, respectively. Clinical severity of alpha-thalassemia correlates with the number of affected alpha-globin genes, yielding a spectrum of clinical manifestations from mild to severe anemia. Routine diagnosis involves Hb analysis and PCR-based methods, yet identifying rare variants necessitates comprehensive clinical and hematologic laboratory data. The knowledge of phenotype and genotype correlation is useful for genetic counseling and treatment planning. CASE REPORT A 59-year-old Thai woman presented with chronic anemia. Her baseline Hb level ranged between 8.0 and 9.0 g/dL, with no history of transfusion. Physical examination showed mild pallor, without enlarged liver and spleen. Laboratory investigations showed microcytic, hypochromic anemia and abnormal Hb peak by Hb analysis (retention time 4.58 min by HPLC method). Common alpha-globin gene deletions, including the Southeast-Asian/Thai 3.7 kb and 4.2 kb deletions were tested using gap-PCR, with none of these deletions detected. Direct DNA sequencing revealed a compound heterozygosity of Hb Jax (HBA2: c.44G>C) and Hb Constant Spring (HBA2: c.427T>C). CONCLUSIONS Compound heterozygosity of Hb Jax and Hb Constant Spring results in microcytic anemia. Hb Jax can be identified by Hb analysis, and diagnosis can be confirmed by direct DNA sequencing method. Coinheritance of Hb Jax and alpha-globin variants should be considered in cases with microcytic anemia and a specific Hb peak seen in Hb chromatogram.

Noninvasive Prenatal Diagnosis of Beta-Thalassemia Disease by Using Digital PCR Analysis of Cell-Free Fetal DNA in Maternal Plasma.

INTRODUCTION: Prenatal diagnosis of thalassemia disease was usually based on invasive technique. Noninvasive diagnosis using cell-free fetal DNA (cff-DNA) was described with various laboratory techniques. The aim of this study was to identify the performance of dPCR for analyzing cff-DNA in maternal plasma to diagnose fetal beta-thalassemia diseases. METHODS: Thirty-five couples at risk of fetal beta-thalassemia disease caused by four common mutations of HBB were enrolled at 12-18 weeks. The dPCR assay was designed to detect and quantify paternally inherited beta-thalassemia allele (PIB) and maternally inherited beta-thalassemia allele (MIB) from cff-DNA in maternal plasma. RESULTS: Of 29 couples with different paternal/maternal mutations, all cases who inherited paternal mutation had detectable PIB-M. The MIB-mutant/wild-type (MIB-M/MIB-N) ratio in the mothers whose fetuses did not inherit maternal mutation was 0.87 ± 0.07 which was significantly lower than that of the mothers whose fetuses inherited maternal mutation, 1.01 ± 0.05. The sensitivity and specificity of MIB-M/MIB-N ratio >0.95 in predicting fetus inheriting maternal mutation were 100 and 92.3%, respectively. In four couples with same paternal/maternal mutation, IB-M/IB-N ratio of >0.95 correctly predicted the presence of an inheritance of at least one beta-thalassemia allele. In two couples with paternal Hb E/beta-thalassemia, the presence of PIB-M and the MIB-M/MIB-N ratio of >0.95 correctly predicted the presence of paternal/maternal mutations, respectively. CONCLUSIONS: The method of analyzing cff-DNA in maternal plasma by dPCR is efficient for prenatal diagnosis of beta-thalassemia.

Severe neonatal haemolytic anaemia caused by compound heterozygous KLF1 mutations: report of four families and literature review.

Mutations in the KLF1 gene, which encodes a transcription factor playing a role in erythropoiesis, have recently been demonstrated to be a rare cause of hereditary haemolytic anaemia. We described the genotypic and phenotypic spectra of four unrelated families with compound heterozygous class 2/class 3 KLF1 mutations. All patients had p.G176RfsX179 on one allele and either p.A298P, p.R301H or p.G335R on the other allele. All presented on the first day of life with severe haemolytic anaemia with abnormal red blood cell morphology, markedly increased nucleated red blood cells and hyperbilirubinaemia. Three patients later became transfusion-dependent. All parents with heterozygous KLF1 mutation without co-inherited thalassaemia had normal to borderline mean corpuscular volume (MCV) and normal to slightly elevated Hb F. Fifteen previously reported cases of biallelic KLF1 mutations were identified from a literature review. All except one presented with severe haemolytic anaemia in the neonatal period. Our finding substantiates that compound heterozygous KLF1 mutations are associated with severe neonatal haemolytic anaemia and expands the haematologic phenotypic spectrum. In carriers, the previously suggested findings of low MCV, high Hb A2 and high Hb F are inconsistent; thus this necessitates molecular studies for the identification of carriers.

Coinherited Hemoglobin H/Constant Spring Disease and Heterozygous Hemoglobin Tak Causing Severe Hemolytic Anemia in a Thai Boy.

Hemoglobin (Hb) H/Constant Spring disease is a common nondeletional Hb H disease, typically causing a more severe phenotype than the deletional Hb H disease counterpart. Hb Tak, resulting from a dinucleotide insertion (+AC) at codon 146 of beta-globin gene, has an increased oxygen affinity and usually presents with polycythemia. We studied a case of a 4-year-old Thai boy with a severe, early-onset anemia. To our knowledge, he is the first reported patient with Hb H/Constant Spring disease and heterozygous Hb Tak. Trio-whole-exome sequencing does not identify other genetic variants that may contribute to the severity of anemia. The observation suggests that coinherited Hb H/Constant Spring and heterozygous Hb Tak lead to severe hemolytic anemia.

Molecular characteristics of thalassemia and hemoglobin variants in prenatal diagnosis program in northern Thailand.

Molecular analysis of globin genes is an essential process for prenatal diagnosis (PND) of severe thalassemia. This study aimed to describe the molecular characteristics of thalassemia and hemoglobin (Hb) variants in PND program in northern Thailand. The type and frequency of globin gene mutations from 1290 couples at risk of fetal severe thalassemia diseases that were tested at Thalassemia Laboratory at Chiang Mai University from 2012 to 2017 were retrospectively reviewed. The PND program detected 444 (34.4%), 196 (15.2%) and 642 (49.8%) couples at risk of fetal Hb Bart's hydrops fetalis, beta-thalassemia major (BTM) and beta-thalassemia/Hb E disease, respectively. Coinheritance of more than one type of thalassemia was common and eight (0.6%) couples were at risk of two types of severe thalassemia. There were two types of alpha0-thalassemia; 893 (99.7%) Southeast Asian and 3 (0.3%) Thai deletions. Twenty beta-globin gene mutations were found with 94.3% of beta0-thalassemia. The codon 41/42 (- TTCT), codon 17 (A>T), IVS-I-1 (G>T) and codon 71/72 (+ A) comprised 90% of beta-thalassemia mutations. The study shows a high percentage of couples at risk of fetal Hb Bart's hydrops fetalis and BTM. The percentage of beta0-thalassemia is higher than those seen in other regions of Thailand.

Borderline hemoglobin A2 levels in northern Thai population: HBB genotypes and effects of coinherited alpha-thalassemia.

INTRODUCTION: Identification of beta-thalassemia carrier in prenatal screening relies on the elevated Hb A2 level. Borderline Hb A2 levels pose a diagnostic challenge. We determined the HBB genotypes in subjects with borderline Hb A2 in northern Thailand and studied the effects of coinherited alpha0-thalassemia on Hb A2 levels. METHODS: Blood samples with Hb A2 3.1-10.0% from 2193 samples submitted for prenatal thalassemia screening were selected. Information on HBB genotypes and coinherited alpha0-thalassemia were collected. All samples with unknown HBB genotypes underwent an automated DNA sequencing. The Hb A2 levels were compared according to the coinherited alpha0-thalassemia. RESULTS: HBB mutations were found in 298 (98.7%) of 302 samples with Hb A2 4.0-10.0%. In the 106 samples with Hb A2 3.1-3.9%, six had HBB mutations; four Hb Dhonburi [codon 126 (T > G)], one CAP site mutation [CAP + 1 (A > C)] and one beta0-thalassemia [codon 41/42 (-TTCT)] with a coinherited HBD mutation [nt-77 (T > C)]. The Hb A2 levels in beta-thalassemia carriers with and without coinherited alpha0-thalassemia were not significantly different. CONCLUSIONS: HBB mutations in northern Thais with borderline Hb A2 levels comprise an unstable variant Hb Dhonburi and CAP + 1 (A > C) mutation. Coinherited HBD mutation lowers Hb A2 and can cause a misidentification of a beta-thalassemia carrier.

Calreticulin mutation analysis in non-mutated Janus kinase 2 essential thrombocythemia patients in Chiang Mai University: analysis of three methods and clinical correlations.

OBJECTIVES: The primary objective was to determine the prevalence of calreticulin (CALR) mutation in patients with non-JAK2V617F mutated essential thrombocythemia (ET). The secondary objectives were to evaluate the accuracy of CALR mutation analysis by high-resolution melting (HRM) analysis and real-time polymerase chain reaction (PCR) compared with DNA sequencing and to compare clinical characteristics of CALR mutated and JAK2V617F mutated ET. METHODS: This was a prospective cohort study involving ET patients registered at Chiang Mai University in the period September 2015-September 2017 who were aged more than 2 years, and did not harbor JAK2V617F mutation. The presence of CALR mutation was established by DNA sequencing, HRM, and real-time PCR for type 1 and type 2 mutation. Clinical data were compared with that from ET patients with mutated JAK2V617F. RESULTS: Twenty-eight patients were enrolled onto the study. CALR mutations were found in 10 patients (35.7%). Three patients had type 1 mutation, 5 patients had type 2 mutation, 1 patient had type 18 mutation, and 1 patients had novel mutations (c.1093 C-G, c.1098_1131 del, c.1135 G-A). HRM could differentiate between the types of mutation in complete agreement with DNA sequencing. Patients with a CALR mutation showed a significantly greater male predominance and had a higher platelet count when compared with 42 JAK2V617F patients. DISCUSSION AND CONCLUSIONS: The prevalence of CALR mutation in JAK2V617F-negative ET in this study is 35.7%. HRM is an effective method of detecting CALR mutation and is a more advantageous method of screening for CALR mutation.

High-resolution melting analysis for prenatal diagnosis of beta-thalassemia in northern Thailand.

High-resolution melting (HRM) analysis is a rapid mutation analysis which assesses the pattern of reduction of fluorescence signal after subjecting the amplified PCR product with saturated fluorescence dye to an increasing temperature. We used HRM analysis for prenatal diagnosis of beta-thalassemia disease in northern Thailand. Five PCR-HRM protocols were used to detect point mutations in five different segments of the beta-globin gene, and one protocol to detect the 3.4 kb beta-globin deletion. We sought to characterize the mutations in carriers and to enable prenatal diagnosis in 126 couples at risk of having a fetus with beta-thalassemia disease. The protocols identified 18 common mutations causing beta-thalassemia, including the rare codon 132 (A-T) mutation. Each mutation showed a specific HRM pattern and all results were in concordance with those from direct DNA sequencing or gap-PCR methods. In cases of beta-thalassemia disease resulting from homozygosity for a mutation or compound heterozygosity for two mutations on the same amplified segment, the HRM patterns were different to those of a single mutation and were specific for each combination. HRM analysis is a simple and useful method for mutation identification in beta-thalassemia carriers and prenatal diagnosis of beta-thalassemia in northern Thailand.

Prevalence and molecular characterization of glucose-6-phosphate dehydrogenase deficiency in northern Thailand.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is one of the most common inherited enzymopathies in endemic areas of malaria including Southeast Asia. The molecular features of G6PD deficiency are similar among Southeast Asian population, with differences in the type of the prominent variants in each region. This study determined the prevalence and molecular characteristics of G6PD deficiency in northern Thailand. Quantitative assay of G6PD activity was conducted in 566 neonatal cord blood samples and 6 common G6PD mutations were determined by PCR-restriction fragment length polymorphism method on G6PD complete and intermediate deficiency samples. Ninety newborns had G6PD deficiency, with prevalence in male newborns of 17% and that of female newborns having an intermediate and complete deficiency of 13% and 2%, respectively. From 95 G6PD alleles tested, G6PD Mahidol, G6PD Kaiping, G6PD Canton, G6PD Viangchan, G6PD Union, and G6PD Chinese-5 was detected in 19, 17, 15, 13, 7, and 2 alleles, respectively. Our study shows that the prevalence of G6PD deficiency in northern Thai population is high and combination of the common Chinese mutations is the majority, a distribution different from central and southern Thailand where G6PD Viangchan is the prominent variant. These findings suggest a higher proportion of assimilated Chinese ethnic group in the northern Thai population.

Analysis of real-time SYBR-polymerase chain reaction cycle threshold for diagnosis of the alpha-thalassemia-1 Southeast Asian type deletion: application to carrier screening and prenatal diagnosis of Hb Bart's hydrops fetalis.

Without gel electrophoresis and specific probes, the two tubes real-time SYBR-polymerase chain reaction (SYBR-PCR) was setup by using different primer sets: P1/P2 for the detection of wild type alpha-globin gene alleles and P1/P3 for detection of the allele bearing the Southeast Asian (SEA) type (--SEA) deletion. Analyses of the cycle threshold (CT) values obtained by each primer set together with a delta-cycle threshold (DeltaCT) and CT ratio, showed that lower CT values generated by primer sets P1/P2 and P1/P3 were observed in normal and Hb Bart's hydrops fetalis subjects, respectively. In heterozygous subjects the CT values generated by both sets of primers were similar to each other. There was no overlapping of DeltaCT and CT ratio between normal, heterozygous and Hb Bart's hydrops fetalis subjects. Therefore, the two tubes real-time SYBR-PCR could represent a rapid, cost effective, high-throughput assay for screening of carriers and prenatal diagnosis of alpha-thalassemia-1 (alpha-thal-1) with the SEA type (--SEA) deletion.

Detection of alpha-thalassemia-1 Southeast Asian type using real-time gap-PCR with SYBR Green1 and high resolution melting analysis.

Alpha-thalassemia-1 Southeast Asian (SEA) type is the most common genetic disorder in the Asian population. Couples who are both carriers have a 25% chance of conceiving Bart's hydrops fetalis. Therefore, results from carrier screening and prenatal diagnosis frequently need to be available rapidly. A rapid technique for diagnosis of alpha-thalassemia-1 SEA type was implemented. The technique used is based on real-time gap-PCR and high resolution melting (HRM) analysis of the amplified fragment using the Rotor-Gene 6000. The DNA samples used for amplification were obtained from whole blood, cord blood, and chorionic villus sampling (CVS). With this method, the alpha-thalassemia-1 SEA allele can be easily distinguished from wild type alpha-globin gene allele. The real-time gap-PCR and HRM analysis offers additional benefits including minimal labor, rapid turnaround time, and a decreased risk of PCR carryover contamination. It is cost-effective and safe, does not require fluorescently labeled probe and hazardous chemicals. Moreover, it is accurate showing 100% concordance with conventional gap-PCR analysis.