4H or POLR3-related leukodystrophy is inherited in an autosomal recessive fashion and is caused by mutations in one of three genes encoding RNA polymerase III (POLR3) subunits, that is, POLR3A, POLR3B, and POLR1C [8, 12–17]. The gene discussed is POLR1C; the disease is leukodystrophy.