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Rioux AV, Bergeron NA, Riopel J, Marcoux N, Thériault C, Gould PV, Garneau AP, Isenring P. The ever wider clinical spectrum of RMND1-related disorders and limitedness of phenotype-based classifications. J Mol Med (Berl) 2023; 101:1229-1236. [PMID: 37584739 PMCID: PMC10560146 DOI: 10.1007/s00109-023-02356-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 07/10/2023] [Accepted: 08/02/2023] [Indexed: 08/17/2023]
Abstract
RMND1 has been identified as a mitochondriopathy-associated gene less than 12 years ago. The most common phenotype related to this gene is an early onset, severe form of encephalomyopathy that leads to death in a medium time of three years after birth. However, milder and later onset presentations have been reported in some individuals, including two in whom the mitochondriopathy was identified at ~ 40 years of age, and the early onset presentations have been the object of no reports in those who survived beyond age 10. It is thus unclear how lethal RMND1-related conditions really are. We herein describe the oldest case to have been identified hitherto with this condition, i.e., that of a white female who was 61 at the time of diagnosis but was still active in her everyday life. The gene defect identified was nonetheless associated with many manifestations including ovarian insufficiency and sensorineural hearing loss (two features of what is currently designated as Perrault syndrome) as well as chronic renal failure, asymptomatic myopathy, leukopenia, and a few others. In our opinion, this case is of great translational interest for at least three reasons. First, it hints towards the possibility of near-normal life expectancies in some if not many individuals with RMND1 insufficiency. Second, it underlines the wide clinical spectrum associated with this gene. Third, it brings us to question the use of eponyms and syndromic features to identify the true etiology of multisystemic phenotypes. KEY MESSAGES: RMND1-related conditions typically manifest at an early age with a progressive and lethal form of encephalomyopathy. More benign presentations have been described with some being categorized as Perrault syndrome but none have been diagnosed after the age of 45. The clinical spectrum and presenting age of RMND1-related mitochondriopathies are probably much more varied than implied in the current literature. The case reported in this manuscript illustrates the limitedness of phenotype-based classifications of genetic disorders to identify the defect at cause.
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Affiliation(s)
- Alexis V Rioux
- CHU de Québec, Service of Nephrology, Faculty of Medicine, Université Laval, QC, G1R 2J6, Québec, Canada
| | - Nicolas Ad Bergeron
- CHU de Québec, Service of Nephrology, Faculty of Medicine, Université Laval, QC, G1R 2J6, Québec, Canada
| | - Julie Riopel
- CHU de Québec, Service of Pathology, Faculty of Medicine, Université Laval, Québec, QC, G1R 2J6, Canada
| | - Nicolas Marcoux
- CHU de Québec, Service of Hematology, Faculty of Medicine, Université Laval, Québec, QC, G1R 2J6, Canada
| | - Catherine Thériault
- CHU de Québec, Service of Pathology, Faculty of Medicine, Université Laval, Québec, QC, G1R 2J6, Canada
| | - Peter V Gould
- CHU de Québec, Service of Pathology, Faculty of Medicine, Université Laval, Québec, QC, G1R 2J6, Canada
| | - Alexandre P Garneau
- Service de Néphrologie-Transplantation Rénale Adultes, Hôpital Necker‑Enfants Malades, AP‑HP, Inserm U1151, Université Paris Cité, rue de Sèvres, Paris, France
| | - Paul Isenring
- CHU de Québec, Service of Nephrology, Faculty of Medicine, Université Laval, QC, G1R 2J6, Québec, Canada.
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Lin L, Zhang D, Jin Q, Teng Y, Yao X, Zhao T, Xu X, Jin Y. Mutational Analysis of Mitochondrial tRNA Genes in 200 Patients with Type 2 Diabetes Mellitus. Int J Gen Med 2021; 14:5719-5735. [PMID: 34557026 PMCID: PMC8454214 DOI: 10.2147/ijgm.s330973] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 08/25/2021] [Indexed: 12/12/2022] Open
Abstract
Objective Previous studies showed that variants in mitochondrial DNA (mtDNA) are associated with type 2 diabetes mellitus (T2DM). However, the relationships between mitochondrial tRNA (mt-tRNA) variants and T2DM remain poorly understood. Methods In this study, we performed a mutational screening of 22 mt-tRNA genes in a cohort of 200 Han Chinese subjects with T2DM and 200 control subjects through PCR–Sanger sequencing. The identified mt-tRNA variants were assessed for their pathogenicity via the phylogenetic approach, structural and functional analysis. Furthermore, two Han Chinese pedigrees with maternally inherited diabetes and deafness (MIDD) were reported by clinical and genetic assessments. Results A total of 49 genetic variants in mt-tRNA genes were identified; among them, 31 variants (17 pathogenic/likely pathogenic) were absent in controls, located at extremely conserved nucleotides, may have potential structural and functional significance, thereby considered to be T2DM-associated variants. In addition, sequence analysis of entire mitochondrial genomes of the matrilineal relatives from two MIDD pedigrees revealed the occurrence of tRNALeu(UUR) A3243G and T3290C mutations, as well as sets of polymorphisms belonging to mitochondrial haplogroups F2 and D4. However, the lack of any functional variants in connexin 26 gene (GJB2) and tRNA 5-methylaminomethyl-2-thiouridylate (TRMU) suggested that nuclear genes may not play active roles in clinical expression of MIDD in these pedigrees. Conclusion Our data indicated that mt-tRNA variants were associated with T2DM, screening for mt-tRNA pathogenic mutations was recommended for early detection and prevention of mitochondrial diabetes.
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Affiliation(s)
- Liangyan Lin
- Department of Endocrinology and Metabolism, Yantai Affiliated Hospital of Binzhou Medical University, Yantai, Shandong, People's Republic of China
| | - Dongdong Zhang
- Department of Endocrinology and Metabolism, Yantai Affiliated Hospital of Binzhou Medical University, Yantai, Shandong, People's Republic of China
| | - Qingsong Jin
- Department of Endocrinology and Metabolism, Yantai Affiliated Hospital of Binzhou Medical University, Yantai, Shandong, People's Republic of China
| | - Yaqin Teng
- Department of Endocrinology and Metabolism, Yantai Affiliated Hospital of Binzhou Medical University, Yantai, Shandong, People's Republic of China
| | - Xiaoyan Yao
- Department of Endocrinology and Metabolism, Yantai Affiliated Hospital of Binzhou Medical University, Yantai, Shandong, People's Republic of China
| | - Tiantian Zhao
- Department of Endocrinology and Metabolism, Yantai Affiliated Hospital of Binzhou Medical University, Yantai, Shandong, People's Republic of China
| | - Xinmiao Xu
- Department of Endocrinology, Yantai Yeda Hospital, Yantai, Shandong, People's Republic of China
| | - Yongjun Jin
- Department of Endocrinology and Metabolism, Yantai Affiliated Hospital of Binzhou Medical University, Yantai, Shandong, People's Republic of China
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