Three novel mutations in Chinese patients with CSF1R-related leukoencephalopathy

CSF1R-related encephalopathy refers to adult-onset leukodystrophy with neuroaxonal spheroids and pigmented glia (ALSP) due to CSF1R mutations, which is a rare autosomal dominant white matter disease including two pathological entities, hereditary diffuse leukoencephalopathy with spheroids (HDLS) and pigmentary orthochromatic leukodystrophy (POLD). The aim of this study was to identify additional causative mutations in the CSF1R gene and clarify their pathogenic effects.

Whole-exome sequencing was conducted for nine Chinese patients diagnosed with possible ALSP based on clinical and neuroimaging findings from March 2014 to June 2020 at Xuanwu Hospital (Beijing, China). Variant pathogenicity was assessed according to the American College of Medical Genetics and Genomics and Association for Molecular Pathology (ACMG/AMP) Standards and Guidelines.

Mean ± standard deviation (range) age of disease onset in the nine patients was 39.22±9.63 [25-54] years. Four of the nine patients were male, and four out of nine had a remarkable family history. Seven CSF1R mutations were identified in the nine patients; four (p.G17C, p.R579Q, p.I794T and c.2909_2910insATCA) have been previously reported, while three (p.V613L, p.W821R and c.2442+2_2442+3dupT) were novel. Of the latter, two (p.V613L and p.W821R) were likely pathogenic and 1 (c.2442+2_2442+3dupT) was of uncertain significance according to ACMG/AMP criteria.

These findings expand the mutational spectrum of ALSP and provide a basis for future investigations on etiologic factors and potential management strategies for this disease.