Leukodystrophy, Hypomyelinating, 21 (HLD21)

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OMIM®: ⁵⁷ Hypomyelinating leukodystrophy-21 (HLD21) is an autosomal recessive neurodegenerative disorder characterized by global developmental delay apparent from infancy with loss of motor, speech, and cognitive milestones in the first decades of life. Affected individuals show cerebellar and pyramidal signs, including nystagmus, ataxia, dystonia, and spasticity, resulting in the loss of ambulation. Other more variable features include feeding difficulties, poor overall growth with microcephaly, optic atrophy, and seizures. Brain imaging shows diffuse hypomyelination of the white matter and atrophy of the cerebellum and corpus callosum. The disorder is progressive and may lead to premature death (summary by Dorboz et al., 2018). For a general phenotypic description and a discussion of genetic heterogeneity of HLD, see 312080. (619310) (Updated 08-Dec-2022)

MalaCards based summary: Leukodystrophy, Hypomyelinating, 21, is also known as hld21. An important gene associated with Leukodystrophy, Hypomyelinating, 21 is POLR3K (RNA Polymerase III Subunit K). Affiliated tissues include cerebellum and brain, and related phenotypes are failure to thrive and nystagmus

UniProtKB/Swiss-Prot: ⁷³ An autosomal recessive neurodegenerative disorder characterized by global developmental delay, loss of motor, speech and cognitive milestones in the first decades of life, and diffuse hypomyelination of the white matter and atrophy of the cerebellum and corpus callosum observed on brain imaging. Clinical features include nystagmus, ataxia, dystonia, and spasticity. Other more variable features are feeding difficulties, poor overall growth with microcephaly, optic atrophy, and seizures.The disorder is progressive and may lead to premature death.

Clinical features from OMIM®:

Search Clinical Trials, NIH Clinical Center for Leukodystrophy, Hypomyelinating, 21