It is likely that HLD8-associated mutations of POLR3B proteins, another component forming the catalytic core of RNA polymerase III, appear to be linked to their decreased transcription abilities for rRNAs and tRNAs or downregulation of their expression. This evidence concerns the gene POLR3B and hypomyelinating leukodystrophy 8 with or without oligodontia and-or hypogonadotropic hypogonadism.