_:vb50946193 . _:vb50946193 . . _:vb50946193 . . _:vb50946193 . "disease_ontology"^^ . . "OMIM:619071"^^ . . "DOID:0112153"^^ . _:vb50946193 . "HLD20"^^ . "hypomyelinating leukodystrophy 20"^^ . "A hypomyelinating leukodystrophy characterized by progressive loss of developmental milestones starting at about 12 to 16 months of age after normal early development that has_material_basis_in homozygous or compound heterozygous mutation in CNP on chromosome 17q21.2."^^ .