A hypomyelinating leukodystrophy characterized by autosomal recessive inheritance of childhood onset of progressive motor decline manifest as spasticity, ataxia, tremor, and cerebellar signs, as well as mild cognitive regression that has material basis in homozygous or compound heterozygous mutation in the POLR3A gene on chromosome 10q22. The disease is Monarch Disease Ontology entry MONDO_0011897 (leukodystrophy, hypomyelinating, 7, with or without oligodontia and/or hypogonadotropic hypogonadism). Also known as: 4H syndrome, HLD7, ataxia-delayed dentition-hypomyelination syndrome; odontoleukodystrophy, hypomyelinating leukodystrophy 7 with or without oligodontia and-or hypogonadotropic hypogonadism, leukodystrophy, hypomyelinating, with hypodontia and hypogonadotropic hypogonadism, leukoencephalopathy, hypomyelinating, with ataxia and delayed dentition, leukoencephalopathy-ataxia-hypodontia-hypomyelination syndrome.