Introduction and objectives: Leukodystrophies and genetic leukoencephalopathiesconstitute a vast group of pathologies of the cerebral white matter. The large number of etiopathogenic genes and the frequent unspecificity on the clinical-radiological presentation generate remarkable difficulties in the diagnosis approach. Despite recent and significant developments, molecular diagnostic yield is still less than 50%. Our objective was to develop and explore the usefulness of a new diagnostic procedure using standardized molecular diagnostic tools, and next-generation sequencing techniques. Materials and methods:A prospective, observational, analytical study was conducted in a cohort of 46 patients, evaluated between May 2008 and December 2016, with a suspected genetic leukoencephalopathy or leukodystrophy. A diagnostic procedure was set up using classical monogenic tools in patients with characteristic phenotypes, and next-generation techniques in nonspecific ones.Results: Global diagnostic procedure yield was 57.9%, identifying the etiological pathogenesis in 22 of the 38 studied subjects. Analysis by subgroups, Sanger method, and next-generation sequencing showed a yield of 64%, and 46.1% respectively. The most common pathologies were adrenoleukodystrophy, cerebral autosomal-dominant arteriopathy with subcortical infarcts (CADASIL), and vanishing white matter disease. /journal/ahg 11 12 COHEN ET AL. Conclusions:Our results confirm the usefulness of the proposed diagnostic procedure expressed in a high diagnostic yield and suggest a more optimal cost-effectiveness in an etiological analysis phase. K E Y W O R D Sdiagnostic procedure, genetic leukoencephalopathies, leukodystrophies, next-generation sequencing

IMPORTANCE Cryptogenic strokes constitute approximately 40% of ischemic strokes in young adults, and most meet criteria for the embolic stroke of undetermined source (ESUS). Two randomized clinical trials, NAVIGATE ESUS and RESPECT ESUS, showed a high rate of stroke recurrence in older adults with ESUS but the prognosis and prognostic factors among younger individuals with ESUS is uncertain. OBJECTIVE To determine rates of and factors associated with recurrent ischemic stroke and death and new-onset atrial fibrillation (AF) among young adults. DESIGN, SETTING, AND PARTICIPANTSThis multicenter longitudinal cohort study with enrollment from October 2017 to October 2019 and a mean follow-up period of 12 months ending in October 2020 included 41 stroke research centers in 13 countries. Consecutive patients 50 years and younger with a diagnosis of ESUS were included. Of 576 screened, 535 participants were enrolled after 1 withdrew consent, 41 were found to be ineligible, and 2 were excluded for other reasons. The final follow-up visit was completed by 520 patients. MAIN OUTCOMES AND MEASURESRecurrent ischemic stroke and/or death, recurrent ischemic stroke, and prevalence of patent foramen ovale (PFO). RESULTSThe mean (SD) age of participants was 40.4 (7.3) years, and 297 (56%) participants were male. The most frequent vascular risk factors were tobacco use (240 patients [45%]), hypertension (118 patients [22%]), and dyslipidemia (109 patients [20%]). PFO was detected in 177 participants (50%) who had transthoracic echocardiograms with bubble studies. Following initial ESUS, 468 participants (88%) were receiving antiplatelet therapy, and 52 (10%) received anticoagulation. The recurrent ischemic stroke and death rate was 2.19 per 100 patient-years, and the ischemic stroke recurrence rate was 1.9 per 100 patient-years. Of the recurrent strokes, 9 (64%) were ESUS, 2 (14%) were cardioembolic, and 3 (21%) were of other determined cause. AF was detected in 15 participants (2.8%; 95% CI, 1.6-4.6). In multivariate analysis, the following were associated with recurrent ischemic stroke: history of stroke or transient ischemic attack (hazard ratio, 5.3; 95% CI,, presence of diabetes (hazard ratio, 4.4; 95% CI, 1.5-13), and history of coronary artery disease (hazard ratio, 10; 95% CI,. CONCLUSIONS AND RELEVANCEIn this large cohort of young adult patients with ESUS, there was a relatively low rate of subsequent ischemic stroke and a low frequency of new-onset AF. Most recurrent strokes also met the criteria for ESUS, suggesting the need for future studies to improve our understanding of the underlying stroke mechanism in this population.

This study was approved by the Institutional Ethics Committee of the Hospital JM Ramos Mejia of Buenos Aires, Argentina. All patients and parents provided written informed consent for genetic analyses and use of their anonymized data. All experiments and methods were carried out in accordance with the relevant guidelines and regulations of the Institutional Ethics Committee of the Hospital JM Ramos Mejia of Buenos Aires, Argentina. All clinical investigations have been conducted in accordance with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.Consent to participate: Informed consent for genetic analyses and use of their anonymized data, was obtained from all individual participants and/or parents included in the study. Consent to publish: Patients signed informed consent regarding publishing their dataAll rights reserved. No reuse allowed without permission.

Disability proved to be the main variable related to the presence of sexual dysfunction. Patients with ALS had the worst rates of sexual dysfunction. Patients with MS were similar to the control group. As for the PD group, no patient had normal sexuality. Finally, in stroke patients, the presence of comorbidities and their treatment may have negatively influenced sexuality. These findings showed that patients with chronic neurological diseases have sexual dysfunction and underscore the need for neurologists to know and address this problem.