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Copy number variations (CNVs) involving the α-globin gene cluster can lead to an imbalance in the proportion of α- and β-globin chains and consequently cause clinical symptoms of β-thalassemia. In our case, a 6-year-old boy, clinically diagnosed with β thalassemia intermedia, was admitted for further genetic diagnosis with his family. Targeted sequencing and third generation sequencing (TGS) were used to detect the possible variants of the thalassemia genes. Low-pass whole genome sequencing (lpWGS) was conducted to specify the exact location of relevant CNVs across the genome, which was then validated by multiplex ligation-dependent probe amplification.The results revealed that the patient had a heterozygous β0 mutation of Codon17 (A > T) and a full duplication of the α-globin gene cluster, inherited from his mother and father, respectively. Besides, a novel point mutation within the 5′ untranslated region of β-Globin (HBB: c. −175 (G > A) was only detected in the patient. This study suggests that lpWGS seems a powerful alternative to detect large CNVs related to thalassemia with second intention for more information of the breakpoints and a simultaneous genome-scale detection of other pathogenic CNVs. [ABSTRACT FROM AUTHOR]

Hemoglobinopathies are caused by genetic defects on the globin genes. To date, more than 900 β-globin variants have been recorded worldwide. These gene alterations often cause either a decrease in β-globin synthesis or completely block synthesis, leading to a hemoglobinopathy. While most of these causative mutations are inherited, de novo mutations are quite rare. Here, we investigated three hemoglobinopathy cases. These patients developed severe hemolytic anemia at 3-5 months of age and were transfusion-dependent. In patient 1, a novel β variant, Hb Zunyi [β147(HC3)Stop→Gln; HBB: c.442T>C] was identified. This de novo mutation results in a stop codon substitution to a glutamine residue at codon 147 of the β-globin gene, and leads to severe thalassemia. In patient 2, we discovered the rare Hb Southampton mutation [β106(G8)Leu→Pro; HBB: c.320T>C], while in patient 3, the rare Hb Alesha mutation [β67(E11)Val→Met (GTG>ATG); HBB: c.202G>A] was detected. The identification of the novel β variant, Hb Zunyi, has added to the human globin database and will shed light on future diagnosis of hemoglobinopathy/thalassemia and genetic counseling. [ABSTRACT FROM AUTHOR]

We have developed a new method for non-invasive prenatal testing (NIPT) of paternally inherited fetal mutants for β-thalassemia (β-thal). Specially designed primer-introduced restriction analysis-polymerase chain reaction (PIRA-PCR) were used to detect four major mutations [IVS-II-654, HBB: c.316-197C > T; codon 17 (A > T), HBB: c.52A > T; −28 (A > G), HBB: c.-78A > G and codons 41/42 (-TTCT), HBB: c.126_129delCTTT] causing β-thal in China. The PIRA-PCR assay was first tested in a series of mixed DNA with different concentrations and mixed proportions. Subsequently, this assay was further tested in 10 plasma DNA samples collected from pregnant women. In the DNA mixture simulation test, the PIRA-PCR assay was able to detect 3.0% target genomic DNA (gDNA) mixed in 97.0% wild-type gDNA isolated from whole blood. For plasma DNA testing, the results detected by PIRA-PCR assay achieved 100.0% consistency with those obtained from the amniocentesis analysis. This new method could potentially be used for NIPT of paternally inherited fetal mutants for β-thal. [ABSTRACT FROM AUTHOR]

Here we report a novel β-globin gene mutation in the promoter ( HBB :c.-139_-138delAC) detected by next-generation sequencing (NGS). The proband was a 28-year-old Chinese male, living in Shenzhen City, Guangdong Province, who originates from Hunan Province. The red cell indices were almost normal, with a slightly decreased Red Cell volume Distribution Width(RDW). Capillary electrophoresis (CE) showed the Hb A (93.1%) value was below normal, while the Hb A 2 (4.2%) and Hb F (2.7%) values were both beyond normal. A set of genetic tests of the α and β-globin genes were then performed to determine whether the subject carried any causative mutations. The results of NGS revealed a two-base pair deletion at position -89 to -88( HBB :c.-139_-138delAC）in the heterozygous state, which was subsequently confirmed by Sanger sequencing.