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Neurology. 2014 Nov 18;83(21):1898-905. doi: 10.1212/WNL.0000000000001002. Epub 2014 Oct 22.

Clinical spectrum of 4H leukodystrophy caused by POLR3A and POLR3B mutations.

Author information

1
From the Departments of Child Neurology (N.I.F., M.B., M.S.v.d.K.), Clinical Genetics (R.M.L.v.S., E.S.), and Pathology (M.B.), Neuroscience Campus (N.I.F., M.B., M.S.v.d.K.), and the Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (M.S.v.d.K.), VU University Medical Center, Amsterdam, the Netherlands; the Center for Genetic Medicine Research, Department of Neurology (A.V., A.P.), Children's National Medical Center, Washington, DC; the Institute of Metabolic Disease (R.S.), Baylor Research Institute, Dallas, TX; the Departments of Neurology and Neurosurgery and Human Genetics (B.B.), Montreal Neurological Institute, Canada; the Department of Paediatric Neurology (C.C.-B.), Erasmus University Hospital-Sophia Children's Hospital; the Department of Pathology (J.M.K.), Erasmus Medical Center, Rotterdam, the Netherlands; the Neuroradiology Department (P.S.P.), Centro Hospitalar do Porto, Portugal; the Division of Neurology (D.P.), Children's Hospital of Eastern Ontario, University of Ottawa, Canada; the Department of Paediatric Neurology (S.T.), Royal Belfast Hospital for Sick Children, UK; the Department of Clinical Neurosciences for Children (P.S.), Oslo University Hospital, Ullevål; University of Oslo (P.S.), Norway; the Department of Neurology (T.d.G.), Cincinnati School of Medicine and Cincinnati Children's Hospital Medical Center, OH; INSERM-IECB (S.F.), Pessac, France; the Department of Pediatric Neurology (M.D.), University of British Columbia and British Columbia Children's Hospital, Vancouver, Canada; Kennedy Krieger Institute/Johns Hopkins Medical Institutions (S.N.), Baltimore, MD; and the Departments of Pediatrics, Neurology, and Neurosurgery, Division of Pediatric Neurology (K.G., G.B.), Montreal Children's Hospital, McGill University Health Center, Montreal, Canada. n.wolf@vumc.nl.
2
From the Departments of Child Neurology (N.I.F., M.B., M.S.v.d.K.), Clinical Genetics (R.M.L.v.S., E.S.), and Pathology (M.B.), Neuroscience Campus (N.I.F., M.B., M.S.v.d.K.), and the Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (M.S.v.d.K.), VU University Medical Center, Amsterdam, the Netherlands; the Center for Genetic Medicine Research, Department of Neurology (A.V., A.P.), Children's National Medical Center, Washington, DC; the Institute of Metabolic Disease (R.S.), Baylor Research Institute, Dallas, TX; the Departments of Neurology and Neurosurgery and Human Genetics (B.B.), Montreal Neurological Institute, Canada; the Department of Paediatric Neurology (C.C.-B.), Erasmus University Hospital-Sophia Children's Hospital; the Department of Pathology (J.M.K.), Erasmus Medical Center, Rotterdam, the Netherlands; the Neuroradiology Department (P.S.P.), Centro Hospitalar do Porto, Portugal; the Division of Neurology (D.P.), Children's Hospital of Eastern Ontario, University of Ottawa, Canada; the Department of Paediatric Neurology (S.T.), Royal Belfast Hospital for Sick Children, UK; the Department of Clinical Neurosciences for Children (P.S.), Oslo University Hospital, Ullevål; University of Oslo (P.S.), Norway; the Department of Neurology (T.d.G.), Cincinnati School of Medicine and Cincinnati Children's Hospital Medical Center, OH; INSERM-IECB (S.F.), Pessac, France; the Department of Pediatric Neurology (M.D.), University of British Columbia and British Columbia Children's Hospital, Vancouver, Canada; Kennedy Krieger Institute/Johns Hopkins Medical Institutions (S.N.), Baltimore, MD; and the Departments of Pediatrics, Neurology, and Neurosurgery, Division of Pediatric Neurology (K.G., G.B.), Montreal Children's Hospital, McGill University Health Center, Montreal, Canada.

Abstract

OBJECTIVE:

To study the clinical and radiologic spectrum and genotype-phenotype correlation of 4H (hypomyelination, hypodontia, hypogonadotropic hypogonadism) leukodystrophy caused by mutations in POLR3A or POLR3B.

METHODS:

We performed a multinational cross-sectional observational study of the clinical, radiologic, and molecular characteristics of 105 mutation-proven cases.

RESULTS:

The majority of patients presented before 6 years with gross motor delay or regression. Ten percent had an onset beyond 10 years. The disease course was milder in patients with POLR3B than in patients with POLR3A mutations. Other than the typical neurologic, dental, and endocrine features, myopia was seen in almost all and short stature in 50%. Dental and hormonal findings were not invariably present. Mutations in POLR3A and POLR3B were distributed throughout the genes. Except for French Canadian patients, patients from European backgrounds were more likely to have POLR3B mutations than other populations. Most patients carried the common c.1568T>A POLR3B mutation on one allele, homozygosity for which causes a mild phenotype. Systematic MRI review revealed that the combination of hypomyelination with relative T2 hypointensity of the ventrolateral thalamus, optic radiation, globus pallidus, and dentate nucleus, cerebellar atrophy, and thinning of the corpus callosum suggests the diagnosis.

CONCLUSIONS:

4H is a well-recognizable clinical entity if all features are present. Mutations in POLR3A are associated with a more severe clinical course. MRI characteristics are helpful in addressing the diagnosis, especially if patients lack the cardinal non-neurologic features.

PMID:
25339210
PMCID:
PMC4248461
DOI:
10.1212/WNL.0000000000001002
[Indexed for MEDLINE]
Free PMC Article

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