Table 2.

Clinical, Neuroimaging, and Metabolic Findings in FARS2 Deficiency

Infantile OnsetLater Onset
Number of families 196
Number of individuals 2611
Age at presentation Birth-6 mos (median 35 days; mean 62 days)6 mos-5 yrs (median 2 yrs; mean 2.1 yrs)
Outcome Alive8/23 (age range: 4 mos-3.5 yrs; median 1.6 yrs; mean 1.8 yrs)11/11 (age range: 5.5-41 yrs; median 17 yrs; mean 20 yrs) 1
Deceased15/23 (age range 2 days-15 yrs; median 4 mos; mean 20 mos)0/11
Neurologic manifestations DD/ID24/246/11
Truncal hypotonia16/192/9
Spasticity11/1910/10 (spastic paraplegia)
Seizures24/253/11
Neuroimaging MRI: brain atrophy15/192/11
MRI: thin corpus callosum12/190/11
MRI: hyperintensity of dentate nuclei4/191/11
MRS: ↑ lactate peak8/11NA
Liver Enlarged5/190/11
↑ transaminases14/190/11
↑ GGT 28/8NA
Growth Failure to thrive9/170/8
Microcephaly14/180/7
Metabolic Lactic acidosis21/223/10
↑ CSF lactate7/72/3
↑ plasma alanine13/174/6
ETC enzyme activity Low complex I activity3/71/2
Low complex IV activity4/71/2
Normal activity2/70/2

CSF = cerebrospinal fluid; DD = developmental delay; ETC = electron transport chain; GGT = gamma-glutamyl transferase; ID = intellectual disability; MRI = magnetic resonance imaging; MRS = magnetic resonance spectroscopy

1.

One individual who had hypoxic-ischemic encephalopathy was not included in age-of-onset calculations. For another individual (who had seizures with a normal EEG following vaccination at age 2 months), age of onset was considered to be 3 years (the age at which he was evaluated for developmental delay [Vernon et al 2015].

2.

Elevations up to 1,700 U/L were observed.

From: FARS2 Deficiency

Cover of GeneReviews®
GeneReviews® [Internet].
Adam MP, Feldman J, Mirzaa GM, et al., editors.
Seattle (WA): University of Washington, Seattle; 1993-2024.
Copyright © 1993-2024, University of Washington, Seattle. GeneReviews is a registered trademark of the University of Washington, Seattle. All rights reserved.

GeneReviews® chapters are owned by the University of Washington. Permission is hereby granted to reproduce, distribute, and translate copies of content materials for noncommercial research purposes only, provided that (i) credit for source (http://www.genereviews.org/) and copyright (© 1993-2024 University of Washington) are included with each copy; (ii) a link to the original material is provided whenever the material is published elsewhere on the Web; and (iii) reproducers, distributors, and/or translators comply with the GeneReviews® Copyright Notice and Usage Disclaimer. No further modifications are allowed. For clarity, excerpts of GeneReviews chapters for use in lab reports and clinic notes are a permitted use.

For more information, see the GeneReviews® Copyright Notice and Usage Disclaimer.

For questions regarding permissions or whether a specified use is allowed, contact: ude.wu@tssamda.

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.