Myofibrillar myopathies caused by a de novo heterozygous mutation in MYOT gene: a family report and literature review
10.3760/cma.j.cn115354-20241108-00695
- VernacularTitle:MYOT基因新发杂合变异致肌原纤维肌病一家系报道并文献复习
- Author:
Cong HU
1
;
Xianzhao ZHENG
1
;
Qianqian QU
1
;
Xiaoli MA
1
;
Wenhao CUI
1
;
Yaguang ZHOU
1
;
Jiaxuan WANG
1
;
Haidong LYU
1
Author Information
1. 新乡医学院附属焦作市人民医院神经内科，焦作 454002
- Publication Type:Journal Article
- Keywords:
Myofibrillar myopathy;
MYOT gene;
Clinical feature;
Muscle MRI;
Muscle pathology
- From:
Chinese Journal of Neuromedicine
2024;23(12):1234-1241
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To investigate the clinical phenotypes, muscle magnetic resonance imaging (MRI) and pathological changes, and genetic characteristics of myfibrillar myopathies (MFMs) cuased by MYOT gene mutation. Methods:(1) The clinical data of a MFMs family caused by a de novo frameshift mutation in MYOT gene admitted to Department of Neurology, Jiaozuo People's Hospital Affiliated to Xinxiang Medical University in February 2021 were collected. Electromyography, muscle MRI, and pathological examination were used to confirm the changes of the muscle lesions. MYOT gene mutation in the proband and other patients was detected by next generation sequencing (NGS) and Sanger sequencing, respectively. The 3D structure models of myotilin protein before and after gene mutation were predicted by AlphaFold3 and pymol3. (2) Literature on MFMs caused by MYOT gene mutation was searched from Pubmed and China National Knowledge Infrastructure from the establishment of these databases to July 2024; clinical and genetic characteristics of MFMs caused by MYOT gene mutation were summarized. Results:(1) In the 9 patients from this family, 8 had onset in adolescence (16-20 years old). Unilateral or bilateral hand muscle weakness as the first symptoms appeared in most patients, and then, hand muscle atrophy gradually appeared and slowly progressed to the proximal limbs. Electromyography showed myogenic damage. Muscle MRI showed patchy long T1 and long T2 signal intensity in the bilateral anterior tibial muscles. Muscle pathological staining showed typical rimbed vacuoles, cytoplasm, smear-like muscle fibers and desmin abnormal deposition in some muscle fibers; electron microscopy revealed disorganized myofibril structures, focal myofibril lysis, Z-band streaming, and subsarcolemmal or myofibril mitochondrial accumulation. Heterozygous mutation in MYOT gene c.680_683del (p.Val227GlufsTer10) locus was noted in 8 patients and daughter of the proband. Bioinformatics analysis suggested that MYOT gene c.680_683del mutation could cause premature termination of myotilin translation, leading to the production of a truncated protein, thereby disrupting its normal structure and function. (2) Eighty-nine patients with MFMs caused by MYOT gene mutation in previous literature mainly manifested as chronic progressive weakness of the distal or proximal limbs, with some involving the myocardium, respiratory muscles, or peripheral nerves. A total of 12 MYOT gene mutations were identified, with p. Ser60phe being the most common mutation. Except for p.Tyr4_his9del, being an in-frame mutation, the others were missense mutations. Conclusion:MFMs caused by MYOT gene mutation exhibit obvious clinical heterogeneity, characterized by very slow progression of muscle weakness; MYOT gene locus c.680_683del (p.Val227GlufsTer10) is a de novo heterozygous mutation.
