Intrafamilial clinical variability in individuals carrying the CHCHD10 mutation Gly66Val

• Published in: Acta neurologica Scandinavica Vol. 133; no. 5; pp. 361 - 366
• Main Authors: Pasanen, P., Myllykangas, L., Pöyhönen, M., Kiuru-Enari, S., Tienari, P. J., Laaksovirta, H., Toppila, J., Ylikallio, E., Tyynismaa, H., Auranen, M.
• Format: Journal Article
• Language: English
• Published: Denmark Blackwell Publishing Ltd 01-05-2016; Hindawi Limited
• Subjects: Adult; Charcot-Marie-Tooth Disease - diagnosis; Charcot-Marie-Tooth Disease - genetics; CHCHD10; clinical variability; Female; Humans; Male; Middle Aged; Mitochondrial Proteins - genetics; Mutation, Missense; Pedigree; Phenotype; proximal sensorimotor neuropathy; spinal muscular atrophy; proximal sensorimotor neuropathy; CHCHD10; clinical variability; spinal muscular atrophy
• ISSN: 0001-6314; 1600-0404
• DOI: 10.1111/ane.12470

Objectives
Mutations in the CHCHD10 gene, which encodes a mitochondrially targeted protein, have emerged as an important cause of motor neuron disease and frontotemporal lobar degeneration. The aim of this study was to assess the clinical variability in a large family carrying the p.Gly66Val mutation of the CHCHD10 gene. This mutation has recently been reported to cause late‐onset spinal muscular atrophy (SMAJ) or sensorimotor axonal Charcot–Marie–Tooth neuropathy (CMT2) in the Finnish population.
Materials and methods
Nine affected members of an extended Finnish pedigree were included in the study. Detailed clinical and neurophysiological examinations were performed. The CHCHD10 p.Gly66Val mutation was examined by Sanger sequencing.
Results
The heterozygous p.Gly66Val mutation was present in all affected individuals from whom a DNA sample was available. The clinical phenotype varied from proximal sensorimotor neuropathy to spinal muscular atrophy and in one case resembled motor neuron disease ALS at its early stages. The age of onset varied from 30 to 73 years.
Conclusions
Our data demonstrate that even within the same family, the p.Gly66Val variant can cause variable phenotypes ranging from CMT2‐type axonal neuropathy to spinal muscular atrophy, which may also present as an ALS‐like disease. The spectrum of CHCHD10‐related neuromuscular disease has widened rapidly, and we recommend keeping the threshold for genetic testing low particularly when dominant inheritance or mitochondrial pathology is present.