Insights into phenotypic variability caused by GARS1 pathogenic variants

• Published in: European journal of neurology Vol. 31; no. 10; pp. e16416 - n/a
• Main Authors: Jiménez‐Jiménez, Jesús, Navarrete, Irene, Azorín, Inmaculada, Martí, Pilar, Vílchez, Roger, Muelas, Nuria, Cabello‐Murgui, Javier, Millet, Elvira, Vázquez‐Costa, Juan Francisco, Vílchez, Juan J., Sevilla, Teresa, Sivera, Rafael
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.10.2024; John Wiley and Sons Inc
• Subjects: Adolescent; Adult; Atrophy; axonal CMT; Biopsy; Charcot-Marie-Tooth disease; Charcot-Marie-Tooth Disease - diagnostic imaging; Charcot-Marie-Tooth Disease - genetics; Charcot-Marie-Tooth Disease - pathology; Charcot-Marie-Tooth Disease - physiopathology; Child; Child, Preschool; Cross-Sectional Studies; Density; Female; GARS1 gene; Genetic variability; Glycine-tRNA Ligase - genetics; Hereditary Sensory and Motor Neuropathy - genetics; Hereditary Sensory and Motor Neuropathy - pathology; Hereditary Sensory and Motor Neuropathy - physiopathology; Humans; Magnetic Resonance Imaging; Male; Muscle, Skeletal - diagnostic imaging; Muscle, Skeletal - pathology; Muscle, Skeletal - physiopathology; Muscles; Mutation, Missense; Nerve conduction; Nerve endings; Nerves; Neural Conduction - physiology; Neuropathies; Neuropathy; Observational studies; Original; Phenotype; Phenotypes; Retrospective Studies; Sensory neurons; Skin; skin biopsy; Spinal muscular atrophy; split hand; tRNA; Young Adult; Charcot–Marie–Tooth disease; GARS1 gene; axonal CMT; split hand; skin biopsy
• ISSN: 1351-5101; 1468-1331; 1468-1331
• DOI: 10.1111/ene.16416

Background and Purpose Pathogenic variants of the glycyl‐tRNA synthetase 1 (GARS1) gene have been described as a cause of Charcot–Marie–Tooth disease type 2D, motor axonal neuropathy with upper limb predominance (distal hereditary motor neuropathy [dHMN] type V), and infantile spinal muscular atrophy. Methods This cross‐sectional, retrospective, observational study was carried out on 12 patients harboring the c.794C>T (p.Ser265Phe) missense pathogenic variant in GARS1. The patients' clinical data, nerve conduction studies, magnetic resonance imaging (MRI), and intraepidermal nerve fiber density in skin biopsies were reviewed. Results The mean age at onset was 9.5 years; the intrinsic hand muscles were affected before or at the same time as the distal leg musculature. The clinical examination revealed greater weakness of the distal muscles, with a more pronounced involvement of the thenar complex and the first dorsal interosseous in upper limbs. Electrophysiological studies were concordant with an exclusively motor axonal neuropathy. A pathologic split hand index was found in six patients. Muscle MRI showed predominant fatty infiltration and atrophy of the anterolateral and superficial posterior compartment of the legs. Most patients reported distal pinprick sensory loss. A reduced intraepidermal nerve fiber density was evident in skin biopsies from proximal and distal sites in nine patients. Conclusions GARS1 variants may produce a dHMN phenotype with “split hand” and sensory disturbances, even when sensory nerve conduction studies are normal. This could be explained by a dysfunction of sensory neurons in the dorsal ganglion that is reflected as a reduction of dermal nerve endings in skin biopsies without a distal gradient.