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Expanding the spectrum of PEX16 mutations and novel insights into disease mechanisms

Abstract

Zellweger syndrome spectrum disorders are caused by mutations in any of at least 12 different PEX genes. This includes PEX16, an important regulator of peroxisome biogenesis. Using whole genome sequencing, we detected previously unreported, biallelic variants in PEX16 [NM_004813.2:c.658G>A, p.(Ala220Thr) and NM_004813.2:c.830G>A, p.(Arg277Gln)] in an individual with leukodystrophy, spastic paraplegia, cerebellar ataxia, and craniocervical dystonia with normal plasma very long chain fatty acids. Using olfactory-neurosphere derived cells, a population of neural stem cells, we showed patient cells had reduced peroxisome density and increased peroxisome size, replicating previously reported findings in PEX16 cell lines. Along with alterations in peroxisome morphology, patient cells also had impaired peroxisome function with reduced catalase activity. Furthermore, patient cells had reduced oxidative stress levels after exposure to hydrogen-peroxide (H2O2), which may be a result of compensation by H2O2 metabolising enzymes other than catalase to preserve peroxisome-related cell functions. Our findings of impaired catalase activity and altered oxidative stress response are novel. Our study expands the phenotype of PEX16 mutations by including dystonia and provides further insights into the pathological mechanisms underlying PEX16-associated disorders. Additional studies of the full spectrum of peroxisomal dysfunction could improve our understanding of the mechanism underlying PEX16-associated disorders.

Type Journal
ISBN 2214-4269 (Print) 2214-4269
Authors Kumar, K. R.; Wali, G.; Davis, R. L.; Mallawaarachchi, A. C.; Palmer, E. E.; Gayevskiy, V.; Minoche, A. E.; Veivers, D.; Dinger, M. E.; Mackay-Sim, A.; Cowley, M. J.; Sue, C. M.
Responsible Garvan Author Dr Mark Cowley
Publisher Name MOLECULAR GENETICS AND METABOLISM
Published Date 2018-07-20
Published Volume 16
Published Pages 46-51
Status Published in-print
DOI 10.1016/j.ymgmr.2018.07.003
URL link to publisher's version https://www.ncbi.nlm.nih.gov/pubmed/30094183