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Mansour-Hendili L, Aissat A, Badaoui B, Sakka M, Gameiro C, Ortonne V, Wagner-Ballon O, Pissard S, Picard V, Ghazal K, Bahuau M, Guitton C, Mansour Z, Duplan M, Petit A, Costedoat-Chalumeau N, Michel M, Bartolucci P, Moutereau S, Funalot B, Galactéros F. Exome sequencing for diagnosis of congenital hemolytic anemia. Orphanet J Rare Dis 2020; 15:180. [PMID: 32641076 PMCID: PMC7341591 DOI: 10.1186/s13023-020-01425-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 05/27/2020] [Indexed: 02/07/2023] Open
Abstract
Background Congenital hemolytic anemia constitutes a heterogeneous group of rare genetic disorders of red blood cells. Diagnosis is based on clinical data, family history and phenotypic testing, genetic analyses being usually performed as a late step. In this study, we explored 40 patients with congenital hemolytic anemia by whole exome sequencing: 20 patients with hereditary spherocytosis and 20 patients with unexplained hemolysis. Results A probable genetic cause of disease was identified in 82.5% of the patients (33/40): 100% of those with suspected hereditary spherocytosis (20/20) and 65% of those with unexplained hemolysis (13/20). We found that several patients carried genetic variations in more than one gene (3/20 in the hereditary spherocytosis group, 6/13 fully elucidated patients in the unexplained hemolysis group), giving a more accurate picture of the genetic complexity of congenital hemolytic anemia. In addition, whole exome sequencing allowed us to identify genetic variants in non-congenital hemolytic anemia genes that explained part of the phenotype in 3 patients. Conclusion The rapid development of next generation sequencing has rendered the genetic study of these diseases much easier and cheaper. Whole exome sequencing in congenital hemolytic anemia could provide a more precise and quicker diagnosis, improve patients’ healthcare and probably has to be democratized notably for complex cases.
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Affiliation(s)
- Lamisse Mansour-Hendili
- Département de Biochimie-Biologie Moléculaire, Pharmacologie, Génétique Médicale, AP-HP, Hôpitaux Universitaires Henri Mondor, F-94010, Creteil, France. .,Univ Paris Est Creteil, INSERM, IMRB, F-94010, Creteil, France.
| | - Abdelrazak Aissat
- Département de Biochimie-Biologie Moléculaire, Pharmacologie, Génétique Médicale, AP-HP, Hôpitaux Universitaires Henri Mondor, F-94010, Creteil, France.,Univ Paris Est Creteil, INSERM, IMRB, F-94010, Creteil, France
| | - Bouchra Badaoui
- Département d'hématologie et d'immunologie, AP-HP, Hôpitaux Universitaires Henri Mondor, F-94010, Creteil, France
| | - Mehdi Sakka
- Département de Biochimie-Biologie Moléculaire, Pharmacologie, Génétique Médicale, AP-HP, Hôpitaux Universitaires Henri Mondor, F-94010, Creteil, France.,Univ Paris Est Creteil, INSERM, IMRB, F-94010, Creteil, France
| | - Christine Gameiro
- Département de Biochimie-Biologie Moléculaire, Pharmacologie, Génétique Médicale, AP-HP, Hôpitaux Universitaires Henri Mondor, F-94010, Creteil, France
| | - Valérie Ortonne
- Département de Biochimie-Biologie Moléculaire, Pharmacologie, Génétique Médicale, AP-HP, Hôpitaux Universitaires Henri Mondor, F-94010, Creteil, France
| | - Orianne Wagner-Ballon
- Univ Paris Est Creteil, INSERM, IMRB, F-94010, Creteil, France.,Département d'hématologie et d'immunologie, AP-HP, Hôpitaux Universitaires Henri Mondor, F-94010, Creteil, France
| | - Serge Pissard
- Département de Biochimie-Biologie Moléculaire, Pharmacologie, Génétique Médicale, AP-HP, Hôpitaux Universitaires Henri Mondor, F-94010, Creteil, France.,Univ Paris Est Creteil, INSERM, IMRB, F-94010, Creteil, France
| | - Véronique Picard
- Département d'hématologie, AP-HP, Hôpital Bicêtre, F-94270, Le Kremlin-Bicêtre, France
| | - Khaldoun Ghazal
- Département de Biochimie, AP-HP, Hôpital Bicêtre, F-94270, Le Kremlin-Bicêtre, France
| | - Michel Bahuau
- Département de Biochimie-Biologie Moléculaire, Pharmacologie, Génétique Médicale, AP-HP, Hôpitaux Universitaires Henri Mondor, F-94010, Creteil, France
| | - Corinne Guitton
- Département d'hématologie pédiatrique, AP-HP, Hôpital Bicêtre, F-94270, Le Kremlin-Bicêtre, France
| | - Ziad Mansour
- Clinique ADASSA, Maternité, F-67000, Strasbourg, France
| | - Mylène Duplan
- Département d'onco-hématologie pédiatrique, CHU d'Angers, 4 Rue Larrey, 49100, Angers, France
| | - Arnaud Petit
- Département d'onco-hématologie pédiatrique, AP-HP, Hôpital Armand Trousseau, F-75012, Paris, France
| | | | - Marc Michel
- Univ Paris Est Creteil, INSERM, IMRB, F-94010, Creteil, France.,Département de médecine interne, AP-HP, Hôpitaux Universitaires Henri Mondor, F-94010, Creteil, France
| | - Pablo Bartolucci
- Univ Paris Est Creteil, INSERM, IMRB, F-94010, Creteil, France.,Département de médecine interne, AP-HP, Hôpitaux Universitaires Henri Mondor, F-94010, Creteil, France.,Unité des maladies génétiques du globule rouge (UMGGR), AP-HP, Hôpitaux Universitaires Henri Mondor, F-94010, Creteil, France
| | - Stéphane Moutereau
- Département de Biochimie-Biologie Moléculaire, Pharmacologie, Génétique Médicale, AP-HP, Hôpitaux Universitaires Henri Mondor, F-94010, Creteil, France.,Univ Paris Est Creteil, INSERM, IMRB, F-94010, Creteil, France
| | - Benoît Funalot
- Département de Biochimie-Biologie Moléculaire, Pharmacologie, Génétique Médicale, AP-HP, Hôpitaux Universitaires Henri Mondor, F-94010, Creteil, France.,Univ Paris Est Creteil, INSERM, IMRB, F-94010, Creteil, France
| | - Frédéric Galactéros
- Univ Paris Est Creteil, INSERM, IMRB, F-94010, Creteil, France.,Département de médecine interne, AP-HP, Hôpitaux Universitaires Henri Mondor, F-94010, Creteil, France.,Unité des maladies génétiques du globule rouge (UMGGR), AP-HP, Hôpitaux Universitaires Henri Mondor, F-94010, Creteil, France
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Abstract
alpha-Thalassaemias are genetic defects extremely frequent in some populations and are characterized by the decrease or complete suppression of alpha-globin polypeptide chains. The gene cluster, which codes for and controls the production of these polypeptides, maps near the telomere of the short arm of chromosome 16, within a G + C rich and early-replicating DNA region. The genes expressed during the embryonic (zeta) or fetal and adult stage (alpha 2 and alpha 1) can be modified by point mutations which affect either the processing-translation of mRNA or make the polypeptide chains extremely unstable. Much more frequent are the deletions of variable size (from approximately 3 to more than 100 kb) which remove one or both alpha genes in cis or even the whole gene cluster. Deletions of a single gene are the result of unequal pairing during meiosis, followed by reciprocal recombination. These unequal cross-overs, which produce also alpha gene triplications and quadruplications, are made possible by the high degree of homology of the two alpha genes and of their flanking sequences. Other deletions involving one or more genes are due to recombinations which have taken place within non-homologous regions (illegitimate recombinations) or in DNA segments whose homology is limited to very short sequences. Particularly interesting are the deletions which eliminate large DNA areas 5' of zeta or of both alpha genes. These deletions do not include the structural genes but, nevertheless, suppress completely their expression. Larger deletions involving the tip of the short arm of chromosome 16 by truncation, interstitial deletions or translocations result in the contiguous gene syndrome ATR-16. In this complex syndrome alpha-thalassaemia is accompanied by mental retardation and variable dismorphic features. The study of mutations of the 5' upstream flanking region has led to the discovery of a DNA sequence, localized 40 kb upstream of the zeta-globin gene, which controls the expression of the alpha genes (alpha major regulatory element or HS-40). In the acquired variant of haemoglobin H (HbH) disease found in rare individuals with myelodysplastic disorders and in the X-linked mental retardation associated with alpha-thalassaemia, a profound reduction or absence of alpha gene expression has been observed, which is not accompanied by structural alterations of the coding or controlling regions of the alpha gene complex. Most probably the acquired alpha-thalassaemia is due to the lack of soluble activators (or presence of repressors) which act in trans and affect the expression of the homologous clusters and are coded by genes not (closely) linked to the alpha genes. The ATR-X syndrome results from mutations of the XH2 gene, located on the X chromosome (Xq13.3) and coding for a transacting factor which regulates gene expression. The interaction of the different alpha-thalassaemia determinants results in three phenotypes: the alpha-thalassaemic trait, clinically silent and presenting only limited alterations of haematological parameters, HbH disease, characterized by the development of a haemolytic anaemia of variable degree, and the (lethal) Hb Bart's hydrops fetalis syndrome. The diagnosis of alpha-thalassaemia due to deletions is implemented by the electrophoretic analysis of genomic DNA digested with restriction enzymes and hybridized with specific molecular probes. Recently polymerase chain reaction (PCR) based strategies have replaced the Southern blotting methodology. The straightforward identification of point mutations is carried out by the specific amplification of the alpha 2 or alpha 1 gene by PCR followed by the localization and identification of the mutation with a variety of screening systems (denaturing gradient gel electrophoresis (DGGE), single strand conformation polymorphisms (SSCP)) and direct sequencing.
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Affiliation(s)
- L F Bernini
- Institute of Human Genetics, Medical Faculty, University of Leiden, Sylvius Laboratory, The Netherlands
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