1. POLR3A variants in striatal involvement without diffuse hypomyelination
- Author
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Toshiyuki Fukao, Seiji Watanabe, Tsutomu Ogata, Yu Kono, Takuya Hiraide, Tadashi Kaname, Hirotomo Saitsu, Kazuo Kubota, Mitsuko Nakashima, Nobuyuki Shimozawa, and Tomoko Matsubayashi
- Subjects
Pathology ,medicine.medical_specialty ,Striatum ,Biology ,Compound heterozygosity ,White matter ,03 medical and health sciences ,0302 clinical medicine ,Atrophy ,Developmental Neuroscience ,medicine ,4H leukodystrophy ,POLR3-related leukodystrophy ,whole-exome sequencing ,Exome sequencing ,striatal involvement ,Dystonia ,POLR3A ,Leukodystrophy ,General Medicine ,medicine.disease ,medicine.anatomical_structure ,Pediatrics, Perinatology and Child Health ,Neurology (clinical) ,Abnormality ,030217 neurology & neurosurgery - Abstract
Background Biallelic variants in POLR3A encoding the largest subunit of RNA polymerase III cause POLR3-related (or 4H) leukodystrophy characterized by neurologic dysfunction, abnormal dentition, endocrine abnormalities and ocular abnormality. Recently, whole-exome sequencing enabled the discovery of POLR3A variants in cases lacking diffuse hypomyelination, the principal MRI phenotype of POLR3-related leukodystrophy. Homozygous c.1771-6C > G variants in POLR3A were recently suggested to cause striatal and red nucleus involvement without white matter involvement. Case report: Here, we report three cases in two families with biallelic POLR3A variants. We identified two sets of compound heterozygous variants in POLR3A, c.1771-6C > G and c.791C > T, p.(Pro264Leu) for family 1 and c.1771-6C > G and c.2671C > T, p.(Arg891*) for family 2. Both families had the c.1771-6C > G variant, which led to aberrant mRNA splicing. Neuropsychiatric regression and severe intellectual disability were identified in three patients. Two cases showed dystonia and oligodontia. Notably, characteristic bilateral symmetric atrophy and abnormal signal of the striatum without diffuse white matter signal change were observed in brain MRI of all three individuals. Conclusions Striatum abnormalities may be another distinctive MRI finding associated with POLR3A variants, especially in cases including c.1771-6C > G variants and our cases can expand the phenotypic spectrum of POLR3A-related disorders.
- Published
- 2020