PMC6064823_01
The novel glycyl-tRNA synthetase (GARS) mutation was detected in five individuals with distal hereditary motor neuropathy type V (dHMN-V). (A) Images of the hands of the patients with dHMN-V. II-1: The proband's aunt experienced weakness and muscle atrophy in the upper extremities bilaterally at 20 years of age. The lower extremities were less affected. II-5: The proband's father experienced weakness and muscle atrophy in the upper and lower extremities bilaterally at 16 years of age. III-2: The proband's cousin experienced muscle atrophy in the bilateral interosseous muscle at 6 years of age. III-7: The proband experienced weakness and muscle atrophy in the upper and lower extremities with pes cavus bilaterally at 10 years of age. III-8: The proband's young sister experienced weakness and muscle atrophy in the upper and lower extremities at 9 years of age. (B) The pedigree of the family with dHMN-V. Square = male; circle = female; diagonal black line = deceased individual; black filled symbol = clinically and electromyogram confirmed affected individual; empty symbol = clinically healthy relative; syringe symbol = blood sampled individual; asterisk: individual showing a GARS deleterious variant. (C) Chromatograms of the mutation sites confirmed by Sanger sequencing. Note that the five patients with dHMN-V had a novel homozygous mutation consisting of a guanine-to-thymine substitution at codon 383. Unaffected individuals had T/T, and the affected individuals with symptoms had the heterozygous mutation T/G at the corresponding codon. The red circle indicates codon 383.
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F1
The physical examination revealed pes cavus in the bilateral feet and atrophy in the interosseous muscle and thenar eminence (Figure 1, III-7). The family history showed similar symptoms in five other family members (Figure 1).
Magnetic resonance imaging of II-1 with combined dHMN-V and cerebral small vessel disease (CSVD). Fluid-attenuated inversion recovery (FLAIR) imaging revealed a hyperintensity (yellow arrow) surrounding the lateral ventricle and the bilateral centrum semiovale. Microbleeds (red arrow) and lacunar infarction (blue arrow) were present in the brainstem as observed using susceptibility weighted imaging (SWI) and T2. Magnetic resonance angiography (MRA) revealed normal intracranial arteries.
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F2
The physical examination revealed pes cavus in the bilateral feet and atrophy in the interosseous muscle and thenar eminence (Figure 1, III-7). The brain magnetic resonance imaging of this patient showed key markers of CSVD as follows: white matter hyperintensities around the lateral ventricle and bilateral centrum semiovale; multiple lacunar infarctions and microbleeds in the brainstem; and relatively normal major intracranial arteries (Figure 2).
Schematic representation of GARS gene/protein and location of mutations. (A) cDNA structure of human GARS transcript and domain organization of human GARS protein. Above: mutations that have been previously reported in patients with CMT2D or dHMN. Below: positions of GARS protein changes (L128R) identified in patients with dHMN-V in this study. (B) The human GARS protein contains four functional domains, and the L128R mutation is located in the second catalytic domain. (C) The GARS monomer is displayed as a ribbon diagram. The positions of the amino acids that were substituted in the mutations found in the patients are highlighted in red. (D) Conservation analysis confirmed that the L128R mutation and surrounding amino acid sequences are well conserved among species.
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F3
The physical examination revealed pes cavus in the bilateral feet and atrophy in the interosseous muscle and thenar eminence (Figure 1, III-7). This mutation site and surrounding amino acid sequences were well conserved among different species (Figure 3).
Functional analyses of disease-associated GARS mutations in an in vitro study. Wild-type (WT) and mutant GARS-EGFP were expressed in HEK-293T cells and examined by fluorescence microscopy. WT GARS-EGFP-associated granules within the cell body are indicated by white arrows.
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F4
The physical examination revealed pes cavus in the bilateral feet and atrophy in the interosseous muscle and thenar eminence (Figure 1, III-7). In contrast, L128P GARS-EGFP did not associate with these granules (Figure 4).