The objective of the study is to detail clinical and NOTCH3 gene mutational spectrum in a large group of Italian CADASIL patients. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a familial cerebral small vessels disease caused by mutations in the NOTCH3 gene on 19p13 usually presenting in young or middle adulthood. Characteristic features include migraine, recurrent lacunar stroke, subcortical dementia, mood disturbances and leukoencephalopathy. The disorder is often overlooked and misdiagnosed. CADASIL prevalence and disease burden is still undetermined. We retrospectively reviewed demographic, clinical, and mutational characteristic of all CADASIL patients diagnosed from January 2002 to December 2012 in three referral centers for neurogenetic and cerebrovascular diseases in central Italy. 229 NOTCH3 positive subjects were identified. Mean age at diagnosis was 57.8 ± 14.7 years, and 48.6 ± 17.1 years at first symptom onset. Most frequent clinical symptoms were ischemic events (59 %) and psychiatric disturbances (48 %). The highest percentage of mutations were found on exons 4 and 19 (20.6 and 17.6 % respectively), the remaining being dispersed over the entire EGF-like region of the NOTCH3 gene. 209 patients resided in a circumscribed geographic area which included three regions of the central Italy, yielding a minimum prevalence of 4.1 per 100.000 adult inhabitants. This is the most extensive study on CADASIL in Italy. Clinical phenotype showed several peculiarities in frequency and presentation of the main disease manifestations. Our study enlarges the number of pathogenic NOTCH3 mutations and due to the heterogeneous mutational spectrum observed suggests that full sequencing of exons 2-24 is mandatory for CADASIL screening in the Italian population.

Overall, the recognition of the disease before the development of the full clinical-neuroimaging picture may be challenging. Moreover, as we recently reported, none of the Background and Purpose-Cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) phenotype is highly variable, and, although the full clinical-neuroimaging picture may be suggestive of the disease, no characteristic is pathognomonic. Thus, a genetic test remains the diagnostic gold standard, but because it is costly and time-consuming, a pregenetic screening appears desirable. We aimed at developing the CADASIL scale, a screening tool to be applied in the clinical setting. Methods-A preliminary scale was created assigning weighted scores to common disease features based on their frequencies obtained in a pooled analysis of selected international CADASIL series. The accuracy of the scale versus the genetic diagnosis was tested with receiver operating characteristic analysis after the application of this scale to 61 CADASIL and 54 NOTCH3-negative patients (no pathogenic mutation on exons 2-23 of the NOTCH3 gene). To improve the scale accuracy, we then developed an ad hoc optimization algorithm to detect the definitive scale. A third group of 39 patients affected by sporadic small-vessel disease was finally included in the algorithm to evaluate the stability of the scale. Results-The cutoff score of the definitive CADASIL scale had a sensitivity of 96.7% and a specificity of 74.2%. This scale was robust to contamination of patients with sporadic small-vessel disease. Conclusions-The CADASIL scale is a simple and sufficiently accurate screening tool to select patients with a high probability to be affected by the disease and therefore to be subjected to the genetic testing.

Background and purpose

Although certain clinical and neuroimaging features are more frequent in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) than in NOTCH3-negative patients, none is pathognomonic. Clinicians should be aware that when diagnosing CADASIL, a number of patients with a cerebral disease phenotypically similar to CADASIL emerge. The genetic profile of these diseases and the full phenotypic difference with CADASIL remain to be further defined.