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Xu L, Chen M, Zheng J, Zhang S, Zhang M, Chen L, He Q, Guo D, Lin N, Huang H. Identification of a novel 91.5 kb-deletion (αα) FJ in the α-globin gene cluster using single-molecule real-time (SMRT) sequencing. J Matern Fetal Neonatal Med 2023; 36:2254890. [PMID: 37673790 DOI: 10.1080/14767058.2023.2254890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 08/01/2023] [Accepted: 08/29/2023] [Indexed: 09/08/2023]
Abstract
OBJECTIVES To present a novel 91.5-kb deletion of the α-globin gene cluster (αα)FJ identified by genetic assay and prenatal diagnosis in a Chinese family. SUBJECTS AND METHODS The proband was a 34-year-old G3P1 (Gravida 3, Para 1) female at the gestational age of 21+ weeks with a history of an edematous fetus. A routine genetic assay (reverse dot blot hybridization, RDB) was performed to detect common thalassemia mutations. Multiplex ligation-dependent probe amplification (MLPA) and single-molecule real-time technology (SMRT) were used to detect rare thalassemia mutations. RESULTS The hematological phenotypes of the proband, her mother, elder sister, husband, daughter, and nephew were consistent with the phenotype of α-thalassemia trait. No mutations were found in these family members by RDB, except for the proband's husband who carried an α-globin gene deletion --SEA/αα. MLPA results showed that the proband and other α-thalassemia-suspected relatives had heterozygous deletions around the POLR3K-3-463nt, HS40-178nt, and HBA-HS40-382nt probes. The 5'-breakpoint was out of probe scope and could not be determined. SMRT was performed and a 91.5-kb deletion (NC_000016.10: g.39268_130758del) in the α-globin gene cluster (αα)FJ was identified in the proband and other suspected relatives, which could explain their phenotypes. At the proband's gestational age of 22+ weeks, an amniotic fluid sample was collected and analyzed. As only the 91.5-kb deletion (αα)FJ was identified in the fetus with RDB, MLPA, and SMRT. The proband was suggested to continue the pregnancy. CONCLUSION We first reported a 91.5-kb deletion (NC_000016.10: g.hg38-chr16:39268-_130758del) of the HS-40 region in the α-globin gene cluster (αα)FJ identified in a Chinese family. Since the HS-40 loss of heterozygosity in combination with the heterozygous deletion --SEA might result in Hb Bart's hydrops fetalis, routine genetic assay, and SMRT were recommended to individuals at risk for prenatal diagnosis.
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Affiliation(s)
- Liangpu Xu
- Medical Genetic Diagnosis and Therapy Center of Fujian Maternity and Child Health Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, China
| | - Meihuan Chen
- Medical Genetic Diagnosis and Therapy Center of Fujian Maternity and Child Health Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, China
| | - Junhao Zheng
- Medical Genetic Diagnosis and Therapy Center of Fujian Maternity and Child Health Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, China
- Medical Technology and Engineering College, Fujian Medical University, Fuzhou, China
| | - Siwen Zhang
- Medical Genetic Diagnosis and Therapy Center of Fujian Maternity and Child Health Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, China
- Medical Technology and Engineering College, Fujian Medical University, Fuzhou, China
| | - Min Zhang
- Medical Genetic Diagnosis and Therapy Center of Fujian Maternity and Child Health Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, China
| | - Lingji Chen
- Medical Genetic Diagnosis and Therapy Center of Fujian Maternity and Child Health Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, China
| | - Qianqian He
- Medical Genetic Diagnosis and Therapy Center of Fujian Maternity and Child Health Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, China
| | - Danhua Guo
- Medical Genetic Diagnosis and Therapy Center of Fujian Maternity and Child Health Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, China
| | - Na Lin
- Medical Genetic Diagnosis and Therapy Center of Fujian Maternity and Child Health Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, China
| | - Hailong Huang
- Medical Genetic Diagnosis and Therapy Center of Fujian Maternity and Child Health Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, China
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Feng J, Mao A, Lu Y, Shi H, Meng W, Liang C. Molecular characterization of a novel 83.9-kb deletion of the α-globin upstream regulatory elements by long-read sequencing. Blood Cells Mol Dis 2023; 103:102764. [PMID: 37336681 DOI: 10.1016/j.bcmd.2023.102764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 05/31/2023] [Accepted: 06/06/2023] [Indexed: 06/21/2023]
Abstract
Inherited deletions of upstream regulatory elements of α-globin genes give rise to α-thalassemia, which is an autosomal recessive monogenic disease. However, conventional thalassemia target diagnosis often fails to identify these rare deletions. Here we reported a family with two previous pregnancies of Hb Bart's hydrops fetalis and was seeking for prenatal diagnosis during the third pregnancy. Both parents had low level of Hemoglobin A2 indicating α-thalassemia. Conventional Gap-PCR and PCR-reverse dot blot showed the father carried -SEA deletion but did not identify any variants in the mother. Multiplex ligation-dependent probe amplification identified a deletion containing two HS-40 probes but could not determine the exact region. Finally, a long-read sequencing (LRS)-based approach directly identified that the exact deletion region was chr16: 48,642-132,584, which was located in the α-globin upstream regulatory elements and named (αα)JM after the Jiangmen city. Gap-PCR and Sanger sequencing confirmed the breakpoint. Both the mother and fetus from the third pregnancy carried heterozygous (αα)JM, and the fetus was normally delivered at gestational age of 39 weeks. This study demonstrated that LRS technology had great advantages over conventional target diagnosis methods for identifying rare thalassemia variants and assisted better carrier screening and prenatal diagnosis of thalassemia.
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Affiliation(s)
- Jianjiang Feng
- Center for Medical Genetics, Jiangmen Maternal & Child Health Care Hospital, Jiangmen 529000, Guangdong, China
| | - Aiping Mao
- Berry Genomics Corporation, Beijing 102200, China
| | - Ye Lu
- Center for Medical Genetics, Jiangmen Maternal & Child Health Care Hospital, Jiangmen 529000, Guangdong, China
| | - Haihong Shi
- Center for Medical Genetics, Jiangmen Maternal & Child Health Care Hospital, Jiangmen 529000, Guangdong, China
| | - Wanli Meng
- Berry Genomics Corporation, Beijing 102200, China
| | - Chen Liang
- Center for Medical Genetics, Jiangmen Maternal & Child Health Care Hospital, Jiangmen 529000, Guangdong, China.
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Capasso S, Cardiero G, Musollino G, Prezioso R, Testa R, Dembech S, Piluso G, Nigro V, Digilio FA, Lacerra G. Functional analysis of three new alpha-thalassemia deletions involving MCS-R2 reveals the presence of an additional enhancer element in the 5' boundary region. PLoS Genet 2023; 19:e1010727. [PMID: 37216374 DOI: 10.1371/journal.pgen.1010727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 03/31/2023] [Indexed: 05/24/2023] Open
Abstract
We report three novel deletions involving the Multispecies Conserved Sequences (MCS) R2, also known as the Major Regulative Element (MRE), in patients showing the α-thalassemia phenotype. The three new rearrangements showed peculiar positions of the breakpoints. 1) The (αα)ES is a telomeric 110 kb deletion ending inside the MCS-R3 element. 2) The (αα)FG, 984 bp-long, ends 51 bp upstream to MCS-R2; both are associated with a severe α-thalassemia phenotype. 3) The (αα)CT, 5058 bp-long starts at position +93 of MCS-R2 and is the only one associated to a mild α-thalassemia phenotype. To understand the specific role of different segments of the MCS-R2 element and of its boundary regions we carried out transcriptional and expression analysis. Transcriptional analysis of patients' reticulocytes showed that (αα)ES was unable to produce α2-globin mRNA, while a high level of expression of the α2-globin genes (56%) was detected in (αα)CT deletion, characterized by the presence of the first 93 bp of MCS-R2. Expression analysis of constructs containing breakpoints and boundary regions of the deletions (αα)CT and (αα)FG, showed comparable activity both for MCS-R2 and the boundary region (-682/-8). Considering that the (αα)CT deletion, almost entirely removing MCS-R2, has a less severe phenotype than the (αα)FG α0thalassemia deletion, removing both MCS-R2 almost entirely and an upstream 679 bp, we infer for the first time that an enhancer element must exist in this region that helps to increase the expression of the α-globin genes. The genotype-phenotype relationship of other previously published MCS-R2 deletions strengthened our hypothesis.
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Affiliation(s)
- Serena Capasso
- Institute of Genetics and Biophysics "Adriano Buzzati Traverso" (IGB-ABT), National Research Council (CNR), Naples, Italy
| | - Giovanna Cardiero
- Institute of Genetics and Biophysics "Adriano Buzzati Traverso" (IGB-ABT), National Research Council (CNR), Naples, Italy
| | - Gennaro Musollino
- Institute of Genetics and Biophysics "Adriano Buzzati Traverso" (IGB-ABT), National Research Council (CNR), Naples, Italy
| | - Romeo Prezioso
- Institute of Genetics and Biophysics "Adriano Buzzati Traverso" (IGB-ABT), National Research Council (CNR), Naples, Italy
| | - Rosario Testa
- A.O.U. Policlinico Rodolico-San Marco, University of Catania, Catania, Italy
| | - Sabrina Dembech
- Central analysis laboratory, Azienda Ospedaliero-Universitaria, Ospedali Riuniti, Foggia, Italy
| | - Giulio Piluso
- Department of Precision Medicine, University of Campania L. Vanvitelli, Naples, Italy
| | - Vincenzo Nigro
- Department of Precision Medicine, University of Campania L. Vanvitelli, Naples, Italy
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy
| | - F Anna Digilio
- Research Institute on Terrestrial Ecosystems (IRET-CNR), National Research Council (CNR), Naples, Italy
| | - Giuseppina Lacerra
- Institute of Genetics and Biophysics "Adriano Buzzati Traverso" (IGB-ABT), National Research Council (CNR), Naples, Italy
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Li Z, Shang X, Luo S, Zhu F, Wei X, Zhou W, Ye Y, Yan T, Cai R, Xu X. Characterization of two novel Alu element-mediated α-globin gene cluster deletions causing α 0-thalassemia by targeted next-generation sequencing. Mol Genet Genomics 2020; 295:505-514. [PMID: 31897801 DOI: 10.1007/s00438-019-01637-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 12/06/2019] [Indexed: 10/25/2022]
Abstract
α-thalassemia is an inherited blood disorder commonly caused by deletions or point mutations involving one or both α-globin genes. Recent studies shed new light on the critical role of upstream enhancers multi-species conserved sequences (MCSs) in the ordered regulation of α-globin gene expression. Herein, we reported two unrelated probands with deletions in α-globin genes and MCSs, respectively. The proband from Family A is a compound heterozygote carrying a known α+ mutation (-α3.7) and a novel 60.2 kb deletion causing the absence of both α-globin genes. The proband from Family B, on the other hand, is a compound heterozygote with a known α0 mutation (--SEA) and a novel deletion involving only upstream regulatory elements MCS-R1, R2 and R3, while the α-globin genes remain intact. Notably, both these two patients suffered varied extent of anemia, indicating that the loss of enhancer elements could equally lead to reduced synthesis of α-globin. Upon these observations, we then confirmed the exact breakpoints of these two novel deletions using a targeted next-generation sequencing (NGS) previously established by our group, which may enable further elucidation of the rearrangement mechanisms on these deletions and functional dissection of MCSs. Taken together, our study reports a reliable NGS-based molecular screening approach for accurate identification of copy number variations (CNVs) in the α-globin cluster and the genetic diagnosis of these two probands may help to extend the spectrum of α-thalassemia mutations in Chinese population.
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Affiliation(s)
- Zhiming Li
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, Guangdong, China
| | - Xuan Shang
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, Guangdong, China.,Guangdong Genetics Testing Engineering Research Center, Guangzhou, 510515, Guangdong, China
| | - Shiqiang Luo
- Department of Medical Genetics, Liuzhou Municipal Maternity and Child Healthcare Hospital, Liuzhou, 545001, Guangxi, China
| | - Fei Zhu
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, Guangdong, China
| | - Xiaofeng Wei
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, Guangdong, China.,Guangdong Genetics Testing Engineering Research Center, Guangzhou, 510515, Guangdong, China
| | - Wanjun Zhou
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, Guangdong, China.,Guangdong Genetics Testing Engineering Research Center, Guangzhou, 510515, Guangdong, China
| | - Yuhua Ye
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, Guangdong, China.,Guangdong Genetics Testing Engineering Research Center, Guangzhou, 510515, Guangdong, China
| | - Tizhen Yan
- Department of Medical Genetics, Liuzhou Municipal Maternity and Child Healthcare Hospital, Liuzhou, 545001, Guangxi, China
| | - Ren Cai
- Department of Medical Genetics, Liuzhou Municipal Maternity and Child Healthcare Hospital, Liuzhou, 545001, Guangxi, China
| | - Xiangmin Xu
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, Guangdong, China. .,Guangdong Genetics Testing Engineering Research Center, Guangzhou, 510515, Guangdong, China.
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Cheng Y, Cai D, Shang X, Pang D, Wei X, Zhong J, Xu X. A combination of the (αα)
GZ
and ‐‐
SEA
deletions causing a severe form of hemoglobin H disease. Int J Lab Hematol 2019; 42:e80-e83. [DOI: 10.1111/ijlh.13122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 10/24/2019] [Accepted: 11/03/2019] [Indexed: 11/28/2022]
Affiliation(s)
- Yi Cheng
- Department of Medical Genetics School of Basic Medical Sciences Southern Medical University Guangzhou China
| | - Decheng Cai
- Department of Medical Genetics School of Basic Medical Sciences Southern Medical University Guangzhou China
| | - Xuan Shang
- Department of Medical Genetics School of Basic Medical Sciences Southern Medical University Guangzhou China
| | - Dejian Pang
- Department of Medical Genetics School of Basic Medical Sciences Southern Medical University Guangzhou China
| | - Xiaofeng Wei
- Department of Medical Genetics School of Basic Medical Sciences Southern Medical University Guangzhou China
| | - Jianmei Zhong
- Department of Medical Genetics School of Basic Medical Sciences Southern Medical University Guangzhou China
| | - Xiangmin Xu
- Department of Medical Genetics School of Basic Medical Sciences Southern Medical University Guangzhou China
- Guangdong Genetics Testing Engineering Research Center Guangzhou China
- Guangdong Provincial Key Laboratory of Single Cell Technology and Application Guangzhou China
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Abstract
Thalassemia is a disorder of hemoglobin characterized by reduced or absent production of one of the globin chains in human red blood cells with relative excess of the other. Impaired synthesis of β-globin results in β-thalassemia, whereas defective synthesis of α-globin leads to α-thalassemia. Despite being a monogenic disorder, thalassemia exhibits remarkable clinical heterogeneity that is directly related to the intracellular imbalance between α- and β-like globin chains. Novel insights into the genetic modifiers have contributed to the understanding of the correlation between genotype and phenotype and are being explored as therapeutic pathways to cure this life-limiting disease.
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Affiliation(s)
- Sachith Mettananda
- Molecular Hematology Unit, Medical Research Council (MRC), Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Headington, Oxford OX3 9DS, UK; Department of Paediatrics, Faculty of Medicine, University of Kelaniya, Thalagolla Road, Ragama 11010, Sri Lanka
| | - Douglas R Higgs
- Molecular Hematology Unit, Medical Research Council (MRC), Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Headington, Oxford OX3 9DS, UK; National Institute for Health Research, Oxford Biomedical Research Centre, Blood Theme, Oxford University Hospitals, Headington, Oxford OX3 9DU, UK.
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