1
|
Saito Y, Ishiyama A, Saito Y, Komaki H, Sasaki M. Myelin abnormalities in merosin-deficient congenital muscular dystrophy. Muscle Nerve 2024; 69:55-63. [PMID: 37933889 DOI: 10.1002/mus.28002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Revised: 10/19/2023] [Accepted: 10/21/2023] [Indexed: 11/08/2023]
Abstract
INTRODUCTION/AIMS Merosin is a protein complex located in the basement membrane of skeletal muscles and laminin α2-containing regions of the central and peripheral nervous systems. However, because of the prominence of muscle-related symptoms, peripheral neuropathy associated with merosin-deficient congenital muscular dystrophy type 1A (MDC1A) has received little clinical attention. This study aimed to present pathological changes in intramuscular nerves of three patients with MDC1A and discuss their relationship with electrophysiological findings to provide new evidence of peripheral nerve involvement in MDC1A. METHODS MDC1A was confirmed by clinical features, muscle biopsy, and genetic testing for variants in LAMA2. To clarify peripheral nerve involvement, we statistically evaluated electrophysiological and muscle pathology findings of intramuscular nerves. These findings were compared with those of age-matched boys with Duchenne muscular dystrophy (DMD) as controls with normal nerves. Nerve conduction studies (NCS) were performed before biopsy. Biopsied intramuscular nerves were examined with electron microscopy using g-ratio, which is the ratio of axon diameter to myelinated fiber diameter. RESULTS The myelin sheaths were significantly thinner in MDC1A patients than in age-matched DMD patients, with a mean g-ratio of 0.76 ± 0.07 in MDC1A patients and 0.65 ± 0.14 in DMD patients (p < .0001). No neuropathic changes were identified in muscle pathology. Low compound muscle action potential amplitudes, positive sharp waves and fibrillation potentials, and low-amplitude motor unit potentials with increased polyphasia indicated myopathic changes; no neurogenic changes were seen. DISCUSSION We postulate that the thin myelin associated with MDC1A reflects the role of merosin in myelin maturation.
Collapse
Affiliation(s)
- Yoshihiko Saito
- Department of Child Neurology, National Center Hospital, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan
- Department of Neuromuscular Research, National Institute of Neuroscience, NCNP, Tokyo, Japan
| | - Akihiko Ishiyama
- Department of Child Neurology, National Center Hospital, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan
- Department of Neuromuscular Research, National Institute of Neuroscience, NCNP, Tokyo, Japan
| | - Yuko Saito
- Department of Clinical Laboratory, National Center Hospital, NCNP, Tokyo, Japan
| | - Hirofumi Komaki
- Department of Child Neurology, National Center Hospital, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan
| | - Masayuki Sasaki
- Department of Child Neurology, National Center Hospital, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan
| |
Collapse
|
2
|
Wang H, Wan Y, Yang Y, Li H, Mao L, Gao S, Xu J, Wang J. Novel compound heterozygous mutations in OCA2 gene associated with non-syndromic oculocutaneous albinism in a Chinese Han patient: a case report. BMC MEDICAL GENETICS 2019; 20:130. [PMID: 31345173 PMCID: PMC6659248 DOI: 10.1186/s12881-019-0850-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 06/19/2019] [Indexed: 11/24/2022]
Abstract
Background Oculocutaneous albinism (OCA) is a group of rare genetically heterogeneous disorders. The present study aimed to identify the genetic cause of a Chinese Han family with non-syndromic oculocutaneous albinism (OCA). Case presentation Here, we report an 11-month-old male proband from a Chinese Han non-consanguineous family, who presented with milky skin, yellow white hair, nystagmus, astigmatism, and hypermetropia. We performed the targeted next-generation sequencing (NGS) on the proband and identified two novel compound heterozygous variants (c.1865 T > C (p.Leu622Pro) and exons 17–21 deletion) in OCA2 gene associated with OCA type 2 (OCA2, OMIM 203200). Meanwhile, a previously reported heterozygous mutation (c.4805G > A) in MYO7 gene related with Usher syndrome type 1B was found. The online tools SIFT, PolyPhen-2, and Mutation Taster predicted variant c.1865 T > C was probably damaging. The residue p.Leu622 was in a highly conserved region among species by CLUSTALW. Three-dimensional homology model with I-TASSER indicated that p.Leu622Pro variant disturbed the formation of the α-helix, resulting in a random coil structure. The gross deletion (exons 17–21) in OCA2 gene has was not been reported previously. These two novel variants in OCA2 gene were inherited from each parent respectively, after verification by Sanger sequencing and quantitative PCR (qPCR) in the family. Conclusions This study indicates the two novel compound heterozygous mutations in OCA2 gene may be responsible for clinical manifestations of OCA2. It expands the mutation spectrum of OCA2 gene and is helpful to screen for large deletions with targeted NGS protocol in monogenic disease. It also assists the genetic counselling, carrier screening and personalized healthcare of the disease. Electronic supplementary material The online version of this article (10.1186/s12881-019-0850-7) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Hairong Wang
- Anhui Clinical Laboratories, BGI-Anhui, BGI-Shenzhen, Weisan Road, Fuyang, 236000, China
| | - Yang Wan
- Department of Obstetrics and Gynecology, Fuyang People's Hospital, Fuyang, 236000, China
| | - Yun Yang
- Anhui Clinical Laboratories, BGI-Anhui, BGI-Shenzhen, Weisan Road, Fuyang, 236000, China.,Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Hao Li
- Anhui Clinical Laboratories, BGI-Anhui, BGI-Shenzhen, Weisan Road, Fuyang, 236000, China
| | - Liangwei Mao
- Anhui Clinical Laboratories, BGI-Anhui, BGI-Shenzhen, Weisan Road, Fuyang, 236000, China.,College of Life Sciences, Hubei University, Wuhan, 430062, China
| | - Shuyang Gao
- BGI Genomics, BGI-Shenzhen, Shenzhen, 518083, China
| | - Jingjing Xu
- Prenatal diagnosis center, Department of Obstetrics and Gynecology, The First Affiliated Hospital of University of Science and Technology of China, Hefei, 230071, China
| | - Jing Wang
- Prenatal diagnosis center, Department of Obstetrics and Gynecology, The First Affiliated Hospital of University of Science and Technology of China, Hefei, 230071, China.
| |
Collapse
|
3
|
Wang J, Pu Z, Lu Z. Targeted next‑generation sequencing reveals two novel mutations of NBAS in a patient with infantile liver failure syndrome‑2. Mol Med Rep 2017; 17:2245-2250. [PMID: 29207168 PMCID: PMC5783466 DOI: 10.3892/mmr.2017.8191] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 11/21/2017] [Indexed: 11/12/2022] Open
Abstract
Mutations in neuroblastoma amplified sequence (NBAS) cause infantile liver failure syndrome-2 (ILFS2). NBAS is a protein involved in Golgi-to-endoplasmic reticulum retrograde transport. Exon capture in combination with high-throughput sequencing was used to detect NBAS mutations. Via targeted sequencing, two causative mutations were identified from 358 selected genes associated with growth and development diseases; one was a missense mutation, c.3596G>A (p.C1199Y), detected in the coding region of NBAS (NM_015909.3), and the other a splice site mutation, c.209+1G>A. Both of these were heterozygous. The SEC39 structure of the wild-type NBAS protein was compared with a model of the mutated protein. The overall structure of the SEC39 after mutation did not change; however, steric hindrance did increase. In conclusion, two novel NBAS mutations were identified in a 4-year-old Chinese girl with ILFS2.
Collapse
Affiliation(s)
- Jiao Wang
- Department of Clinical Laboratory, Hubei Provincial Hospital of Traditional Chinese Medicine, Wuhan, Hubei 430074, P.R. China
| | - Zhongji Pu
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, Liaoning 116024, P.R. China
| | - Zhenhua Lu
- Department of Clinical Laboratory, Hubei Provincial Hospital of Traditional Chinese Medicine, Wuhan, Hubei 430074, P.R. China
| |
Collapse
|