POLR3B and leukodystrophy: In skin fibroblasts of hypomyelinating leukodystrophy patients with a biallelic pR41W mutation in POLR3K predicted to disrupt its interaction with POLR3B, no changes in the level of the few tRNAs tested by RT-qPCR were observed, with the notable exception of tRNAiMet (initiator methionine tRNA), which showed a mild decrease.