COL4A1/COL4A2 gene duplication causing hereditary cerebral small vessel disease in a Chinese patient.

The pathogenic mechanisms and distinct clinical phenotypes associated with copy number variation (CNV)-mediated hereditary cerebral small vessel disease (hCSVD) remain poorly characterized in current literature. We report the case of a 49-year-old woman presenting with six confirmed episodes of acute ischemic stroke (AIS) over a 7-year disease course. Despite adherence to standardized neuroprotective and rehabilitation therapies, she exhibited persistent neurological deficits, including dysarthria, right-sided hemiparesis, and ataxia. Head MRI revealed prior ischemic infarctions in the bilateral centrum semiovale, periventricular regions, basal ganglia, thalamus, and brainstem. Whole-exome sequencing identified a pathogenic 13.4‑Mb duplication at 13q32.2‑q34, encompassing the COL4A1 and COL4A2 loci, consistent with the molecular diagnostic criteria for COL4A1/COL4A2-related hCSVD. In summary, we report a case of COL4A1/COL4A2 duplication-associated hCSVD in a Chinese patient. This finding expands the known phenotypic spectrum and contributes to the understanding of the pathogenicity of this CNV. It also provides a basis for future studies to investigate whether these underlying mechanisms are conserved across populations.