Neurogenic bladder and neuroendocrine abnormalities in Pol III-related leukodystrophy.

BACKGROUND: Pol III-related leukodystrophies, including 4H leukodystrophy, are recently recognized disorders that comprise hypomyelination and various neurologic and non-neurologic clinical manifestations. We report the unique neurologic presentation of the micturition dysfunction in Pol III-related leukodystrophy and describe the novel endocrine abnormalities in this entity. CASE PRESENTATION: A 32-year-old Caucasian female exhibited chronic urinary incontinence that commenced at the age of 7 years and remained the unexplained symptom more than two decades before the onset of progressive neurologic decline. A transient growth failure and absent sexual development with hypoprolactinemia appeared in the meanwhile. Neurologic, endocrine, neuroradiologic, and genetic evaluation performed only in the patient's thirties, confirmed the diagnosis of 4H leukodystrophy as the only cause of the micturition disturbance. CONCLUSION: The report shows for the first time that an unexplained chronic bladder dysfunction should be evaluated also as a possible 4H leukodystrophy, thus alerting to the unexpected neurologic and endocrine features in 4H leukodystrophy.

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

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.

More than hypomyelination in Pol-III disorder.

The 4H syndrome (hypomyelination, hypodontia, hypogonadotropic hypogonadism) is a newly recognized leukodystrophy. The classical form is characterized by the association of hypomyelination, abnormal dentition, and hypogonadotropic hypogonadism, but the recent identification of 2 genes responsible for the syndrome demonstrates that these 3 main characteristics can be variably combined among "Pol-III (polymerase III)-related leukodystrophies." The pathophysiology of this group of diseases is still to be elucidated, and there are no neuropathologic descriptions of brain tissue. We report the clinical, neuroradiologic, and neuropathologic findings of a patient affected by 4H syndrome with confirmed POLR3A mutations. We found a marked loss of oligodendrocytes, varying in severity in different brain regions, and accompanied by severe loss of myelin, moderately severe loss of axons, and patchy perivascular regions of better preserved white matter. There was relatively mild white matter astrogliosis and microgliosis. A macrophage reaction involving viable normal-appearing oligodendroglia suggests the possibility of an immunologic process in this disorder. Cortical laminar astrogliosis and mineralization of Layers I and II in particular were present. Thus, despite the uniformly hypomyelinating pattern seen on magnetic resonance imaging, neuropathologic examination reveals a complex heterogeneous leukodystrophy with prominent neuroaxonal and glial involvement in this disorder.

4H syndrome with late-onset growth hormone deficiency caused by POLR3A mutations.

OBJECTIVE: To report a novel clinical and genetic presentation of a patient with 4H syndrome, which is a recently described leukodystrophy syndrome characterized by ataxia, hypomyelination, hypodontia, and hypogonadotropic hypogonadism. DESIGN: Case report. SETTING: University teaching hospital. PATIENT: A 20-year-old male patient with 4H syndrome. RESULTS: The patient was found to have delayed tooth eruption and a late-onset growth hormone deficiency without overt growth failure. He was a compound heterozygote for the novel missense mutations R1005H and A1331T of POLR3A, which codes for the largest subunit of RNA polymerase III. CONCLUSION: This is the first report of this type of leukodystrophy from southeastern Europe, which suggests that POLR3A mutations should be suspected in patients with hypomyelination and various central nervous system­based endocrine abnormalities.