WARS2 and Failure to thrive: However, the clinical spectrum of WARS2 mutations seems to be quite broad, including fatal and nonfatal neonatal lactic acidosis, infantile leukoenchephalopathy, spastic quadriplegia, epilepsy, microcephaly, failure to thrive, developmental delay, intellectual disability, ataxia, athetosis, and muscular hypotonia (summarized in Table 1).