Prevalence of CADASIL and Fabry Disease in a Cohort of MRI Defined Younger Onset Lacunar Stroke

Abstract

Background and purpose: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), caused by mutations in the NOTCH3 gene, is the most common monogenic disorder causing lacunar stroke and cerebral small vessel disease (SVD). Fabry disease (FD) due to mutations in the GLA gene has been suggested as an underdiagnosed cause of stroke, and one feature is SVD. Previous studies reported varying prevalence of CADASIL and FD in stroke, likely due to varying subtypes studied; no studies have looked at a large cohort of younger onset SVD. We determined the prevalence in a well-defined, MRI-verified cohort of apparently sporadic patients with lacunar infarct.

Methods: Caucasian patients with lacunar infarction, aged ≤70 years (mean age 56.7 (SD8.6)), were recruited from 72 specialist stroke centres throughout the UK as part of the Young Lacunar Stroke DNA Resource. Patients with a previously confirmed monogenic cause of stroke were excluded. All MRI's and clinical histories were reviewed centrally. Screening was performed for NOTCH3 and GLA mutations.

Results: Of 994 subjects five had pathogenic NOTCH3 mutations (R169C, R207C, R587C, C1222G and C323S) all resulting in loss or gain of a cysteine in the NOTCH3 protein. All five patients had confluent leukoaraiosis (Fazekas grade ≥2). CADASIL prevalence overall was 0.5% (95% CI 0.2%-1.1%) and among cases with confluent leukoaraiosis 1.5% (95% CI 0.6%-3.3%). No classic pathogenic FD mutations were found; one patient had a missense mutation (R118C), associated with late-onset FD.

Conclusion: CADASIL cases are rare and only detected in SVD patients with confluent leukoaraiosis. No definite FD cases were detected.

Fig 1. FLAIR Brain MRIs scans from two of the patients with notch 3 mutations.

The upper panel 1 shows images from patient 1 (R169C), and the lower panel two shows images from patient 2 panel 2 (C1222G). These show leukoaraiosis in both cases (images C and D) but minimal anterior pole involvement in patient 1 (image upper panel A) and no involvement in patient 2 (image lower panel A). Patient 1 also shows confluent external capsule involvement (image B), but this is absent from patient 4 (lower panel B).

Fig 2. Brain MRI (T2-Weighted) of the patient carrying the GLA mutation R118C.

Two lacunes are present in the right caudate nucleus and external capsule (C). An area of white matter hyperintensity is present in the peripheral right posterior frontal white matter (D). There were no abnormalities in the posterior circulation.