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Technological Improvements in the Genetic Diagnosis of Rett Syndrome Spectrum Disorders. Int J Mol Sci 2021; 22:ijms221910375. [PMID: 34638716 PMCID: PMC8508637 DOI: 10.3390/ijms221910375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/17/2021] [Accepted: 09/22/2021] [Indexed: 11/17/2022] Open
Abstract
Rett syndrome (RTT) is a severe neurodevelopmental disorder that constitutes the second most common cause of intellectual disability in females worldwide. In the past few years, the advancements in genetic diagnosis brought by next generation sequencing (NGS), have made it possible to identify more than 90 causative genes for RTT and significantly overlapping phenotypes (RTT spectrum disorders). Therefore, the clinical entity known as RTT is evolving towards a spectrum of overlapping phenotypes with great genetic heterogeneity. Hence, simultaneous multiple gene testing and thorough phenotypic characterization are mandatory to achieve a fast and accurate genetic diagnosis. In this review, we revise the evolution of the diagnostic process of RTT spectrum disorders in the past decades, and we discuss the effectiveness of state-of-the-art genetic testing options, such as clinical exome sequencing and whole exome sequencing. Moreover, we introduce recent technological advancements that will very soon contribute to the increase in diagnostic yield in patients with RTT spectrum disorders. Techniques such as whole genome sequencing, integration of data from several “omics”, and mosaicism assessment will provide the tools for the detection and interpretation of genomic variants that will not only increase the diagnostic yield but also widen knowledge about the pathophysiology of these disorders.
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Velasco K, St-Louis JL, Hovland HN, Thompson N, Ottesen Å, Choi MH, Pedersen L, Njølstad PR, Arnesen T, Fjeld K, Aukrust I, Myklebust LM, Molven A. Functional evaluation of 16 SCHAD missense variants: Only amino acid substitutions causing congenital hyperinsulinism of infancy lead to loss-of-function phenotypes in vitro. J Inherit Metab Dis 2021; 44:240-252. [PMID: 32876354 DOI: 10.1002/jimd.12309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 08/24/2020] [Accepted: 08/28/2020] [Indexed: 12/26/2022]
Abstract
Short-chain 3-hydroxyacyl-CoA dehydrogenase (SCHAD), encoded by the HADH gene, is a ubiquitously expressed mitochondrial enzyme involved in fatty acid oxidation. This protein also plays a role in insulin secretion as recessive HADH mutations cause congenital hyperinsulinism of infancy (CHI) via loss of an inhibitory interaction with glutamate dehydrogenase (GDH). Here, we present a functional evaluation of 16 SCHAD missense variants identified either in CHI patients or by high-throughput sequencing projects in various populations. To avoid interactions with endogenously produced SCHAD protein, we assessed protein stability, subcellular localization, and GDH interaction in a SCHAD knockout HEK293 cell line constructed by CRISPR-Cas9 methodology. We also established methods for efficient SCHAD expression and purification in E. coli, and tested enzymatic activity of the variants. Our analyses showed that rare variants of unknown significance identified in populations generally had similar properties as normal SCHAD. However, the CHI-associated variants p.Gly34Arg, p.Ile184Phe, p.Pro258Leu, and p.Gly303Ser were unstable with low protein levels detectable when expressed in HEK293 cells. Moreover, CHI variants p.Lys136Glu, p.His170Arg, and p.Met188Val presented normal protein levels but displayed clearly impaired enzymatic activity in vitro, and their interaction with GDH appeared reduced. Our results suggest that pathogenic missense variants of SCHAD either make the protein target of a post-translational quality control system or can impair the function of SCHAD without influencing its steady-state protein level. We did not find any evidence that rare SCHAD missense variants observed only in the general population and not in CHI patients are functionally affected.
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Affiliation(s)
- Kelly Velasco
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Johanna L St-Louis
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Henrikke N Hovland
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Nels Thompson
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Åsta Ottesen
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Man Hung Choi
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
- Department of Pathology, Haukeland University Hospital, Bergen, Norway
| | - Line Pedersen
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Pål R Njølstad
- Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway
- Department of Pediatrics and Adolescent Medicine, Haukeland University Hospital, Bergen, Norway
| | - Thomas Arnesen
- Department of Biomedicine, University of Bergen, Bergen, Norway
- Department of Biological Sciences, University of Bergen, Bergen, Norway
- Department of Surgery, Haukeland University Hospital, Bergen, Norway
| | - Karianne Fjeld
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
- Department of Medical Genetics, Haukeland University Hospital, Bergen, Norway
| | - Ingvild Aukrust
- Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway
- Department of Medical Genetics, Haukeland University Hospital, Bergen, Norway
| | - Line M Myklebust
- Department of Biomedicine, University of Bergen, Bergen, Norway
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Anders Molven
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
- Department of Pathology, Haukeland University Hospital, Bergen, Norway
- Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway
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Trifonova EA, Swarovskaja MG, Serebrova VN, Kutsenko IG, Agarkova LA, Stepanov IA, Zhilyakova OV, Gabidulina TV, Ijoykina EV, Stepanov VA. Genomic and Postgenomic Technologies in Preeclampsia Genetics. RUSS J GENET+ 2020. [DOI: 10.1134/s1022795420050130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Andrei L, Kasas S, Ochoa Garrido I, Stanković T, Suárez Korsnes M, Vaclavikova R, Assaraf YG, Pešić M. Advanced technological tools to study multidrug resistance in cancer. Drug Resist Updat 2020; 48:100658. [DOI: 10.1016/j.drup.2019.100658] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 09/26/2019] [Accepted: 09/27/2019] [Indexed: 02/06/2023]
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