To further explore this possibility and to determine if liver and kidney dysfunction could be a primary cause of the neuropathy phenotype, blood urea nitrogen (BUN), the liver enzymes glutamate dehydrogenase (GLDH) and alanine transaminase (ALT), and total bilirubin were tested in serum samples from four-week-old GarsNmf249/+ mice and littermate controls (Fig. 5). Here, GPT is linked to neuropathy.