Hypomyelinating leukodystrophy 7 (HLD7) is an autosomal recessive oligodendroglial cell-related myelin disease, which is associated with some nucleotide mutations of the RNA polymerase 3 subunit a (polr3a) gene. Here, POLR3A is linked to leukodystrophy, hypomyelinating, 7, with or without oligodontia and/or hypogonadotropic hypogonadism.