Detecting rare thalassemia in children with anemia using third-generation sequencing.

BACKGROUND: In China, conventional genetic testing methods can only detect common thalassemia variants. Accurate detection of rare thalassemia is crucial for clinical diagnosis, especially for children that need long-term blood transfusion. This study aims to explore the application value of third-generation sequencing (TGS) in the diagnosis of rare thalassemia in children with anemia. METHODS: We enrolled 20 children with anemia, excluding from iron deficiency anemia (IDA). TGS was employed to identify both known and novel thalassemia genotypes, while sanger sequencing was used to confirm the novel mutation detected. RESULTS: Among the 20 samples, we identified 5 cases of rare thalassemia. These included ß-4.9 (hg38,Chr11:5226187-5231089) at HBB gene, α-91(HBA2:c.*91delT), αCD30(HBA2:c.91-93delGAG), Chinese Gγ+(Aγδß)0(NG_000007.3: g .48795-127698 del 78904) and delta - 77(T > C)(HBD:c.-127T>C). Notably, the -SEA/α-91α genotype associated with severe non-deletional hemoglobin H disease (HbH disease) has not been previously reported. Patients with genotypes ß654/ß-4.9 and -SEA/α-91α necessitate long-term blood transfusions, and those with the -SEA/αCD30α, Chinese Gγ+(Aγδß)0 and delta thalassemia demonstrate mild anemia. CONCLUSIONS: TGS demonstrates promising potential as a diagnostic tool for suspected cases of rare thalassemia in children, especially those suspected to have transfusion-dependent thalassemia (TDT).

Identification of a Novel Hb H Disease with Glucose-6-Phosphate Dehydrogenase Deficiency Using Whole Genome Sequencing.

With the development of sequencing technology, more and more rare thalassemia types have been found. In this article, we found a novel Hb H disease combined with glucose-6-phosphate dehydrogenase (G6PD) deficiency through whole genome sequencing (WGS), which was verified by Sanger sequencing and polymerase chain reaction (PCR)-reverse dot-blot hybridization, respectively.

[Application Value of Capillary Electrophoresis in Screeningß-Thalassemia of Children].

OBJECTIVE: to explore the value of capillary electrophoresis in screening ß- thalassemia of children, and to establish the cutoff values of HbA2 and HbF in our laboratory. METHODS: The data of hemoglobin capillary electrophoresis and genetic diagnosis of ß- thalassemia from 886 examined children were retrospectively analyzed. The cutoff values of HbA2 and HbF were determined by ROC curve. RESULTS: The cutoff value of HbA2 screening minor ß- thalassemia was 3.65%, the specificity was 0.996, and the sensitivity was 0.995. The cut-off value of HbF for screening minor ß- thalassemia was 1.45%, specificity was 0.751 and sensitivity was 0.675. Thus, 1 case with codon5 (CCT→C) mutation, 1 case with SEA -HPFH ß deletion, 1 case with - 28 (A→G) merger IVS-Ι-128 (T→G) double heterozygous mutations yet were found out, 1 case with 47 bp ß gene missing has not yet been reported in literature. CONCLUSION: Capillary electrophoresis has more high sensitivity and specificity in the screening of ß- thalassemia in children, especially for the detection of rare ß- thalassemia.

[Serum level of soluble transferrin receptor in children with hemoglobin H disease].

OBJECTIVE: To investigate the serum level of soluble transferrin receptor (sTfR) and its association with the degree of anemia in children with hemoglobin H (HbH) disease. METHODS: A total of 55 children with HbH disease were enrolled as the HbH group, and 30 healthy children were enrolled as the control group. The HbH group was further divided into a deletional HbH disease group and a non-deletional HbH disease group. A retrospective analysis was performed for hematological parameters and serum sTfR level in all groups. RESULTS: Of the 55 children with HbH disease, 39 had deletional HbH disease and 16 had non-deletional HbH disease. Compared with the control group, the deletional and non-deletional HbH disease groups had significantly lower hemoglobin (Hb), mean corpuscular volume (MCV), and mean corpuscular hemoglobin (MCH) and a significantly higher serum level of sTfR. Compared with the deletional HbH disease group, the non-deletional HbH disease group had significantly lower red blood cell count (RBC) and Hb level and significantly higher MCV, MCH, and serum sTfR level. In children with HbH disease, serum sTfR level was negatively correlated with RBC and Hb level (r=-0.739 and -0.667 respectively, P<0.05) and positively correlated with MCV and MCH (r=0.750 and 0.434 respectively, P<0.05). CONCLUSIONS: Serum sTfR level is associated the degree of anemia in children with HbH disease, and sTfR may be a target for the treatment of HbH disease.

[Genotypic and Phenotypic Analysis of αß-Thalassemia in Children].

OBJECTIVE: To analyze the genotype and hematological characteristics of children with αß-thalassemia in Shenzhen area of China. METHODS: The erythrocyte parameters and hemoglobin components of the children were determined by blood routine examination and capillary electrophoresis (CE). Reverse dot blot (RDB) -polymerase chain reaction (PCR) was used to determine gene mutations in α- and ß-thalassemia children. The Gap-PCR was used to determine the gene deletion of α-thalassemia children，while specimens suspected HKαα were determined with nested PCR. RESULTS: Total of 29 complex genotypes were detected from 74 cases of αß-thalassemia, among which 1 case was determined as ß-thalassemia with αααanti4.2/αα and 5 cases were double heterozygous ß-thalassemia combining α-thalassemia with intermediate phenotype. 1 case of ß-28/ßcap+40-43 double heterozygotes combined with --SEA/αα and the other 62 cases were characterized by light ß-thalassemia, 2 cases ofßCAP+40-43/ßN with --SEA/αα showed light α-thalassemia. CONCLUSION: The genotypes of αß-thalassemia in Shenzhen area of China are complex and diverse. The common complex genotypes are similar to those of simple ß-thalassemia. If the genotype and phenotype are not consistent, the existence of rare genotype should be considered.