In Vivo Diagnosis of Synucleinopathies: A Comparative Study of Skin Biopsy and RT-QuIC.

OBJECTIVE: To determine whether (1) immunofluorescence is a reproducible technique in detecting misfolded α-synuclein in skin nerves and subsequently whether (2) immunofluorescence and real-time quaking-induced conversion (RT-QuIC) (both in skin and CSF) show a comparable in vivo diagnostic accuracy in distinguishing synucleinopathies from non-synucleinopathies in a large cohort of patients. METHODS: We prospectively recruited 90 patients fulfilling clinical and instrumental diagnostic criteria for all synucleinopathies variants and non-synucleinopathies (mainly including Alzheimer disease, tauopathies, and vascular parkinsonism or dementia). Twenty-four patients with mainly peripheral neuropathies were used as controls. Patients underwent skin biopsy for immunofluorescence and RT-QuIC; CSF was examined in patients who underwent lumbar puncture for diagnostic purposes. Immunofluorescence and RT-QuIC analysis were made blinded to the clinical diagnosis. RESULTS: Immunofluorescence showed reproducible results between 2 pairs of neighboring skin samples. Both immunofluorescence and RT-QuIC showed high sensitivity and specificity in discriminating synucleinopathies from non-synucleinopathies and controls but immunofluorescence presented higher diagnostic accuracy. Immunofluorescence presented a good level of agreement with RT-QuIC in both skin and CSF in synucleinopathies. CONCLUSIONS: Both immunofluorescence and RT-QuIC showed high diagnostic accuracy, although immunofluorescence displayed the better value as well as optimal reproducibility; they presented a good level of agreement in synucleinopathies, supporting the use of less invasive tests such as skin immunofluorescence or RT-QuIC instead of CSF RT-QuIC as a diagnostic tool for synucleinopathies. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that immunofluorescence or RT-QuIC accurately distinguish synucleinopathies from non-synucleinopathies.

Identification of rare genetic variants in Italian patients with dementia by targeted gene sequencing.

Genetics is intricately involved in the etiology of neurodegenerative dementias. The incidence of monogenic dementia among all neurodegenerative forms is unknown due to the lack of systematic studies and of patient/clinician access to extensive diagnostic procedures. In this study, we conducted targeted sequencing in 246 clinically heterogeneous patients, mainly with early-onset and/or familial neurodegenerative dementia, using a custom-designed next-generation sequencing panel covering 27 genes known to harbor mutations that can cause different types of dementia, in addition to the detection of C9orf72 repeat expansions. Forty-nine patients (19.9%) carried known pathogenic or novel, likely pathogenic, variants, involving both common (presenilin 1, presenilin 2, C9orf72, and granulin) and rare (optineurin, serpin family I member 1 and protein kinase cyclic adenosine monophosphate (cAMP)-dependent type I regulatory subunit beta) dementia-associated genes. Our results support the use of an extended next-generation sequencing panels as a quick, accurate, and cost-effective method for diagnosis in clinical practice. This approach could have a significant impact on the proportion of tested patients, especially among those with an early disease onset.

A new potential biomarker for dementia with Lewy bodies: Skin nerve α-synuclein deposits.

OBJECTIVE: To investigate whether (1) phosphorylated α-synuclein (p-syn) deposits in skin nerves could be useful in differentiating dementia with Lewy bodies (DLB) from different forms of dementia and (2) small fiber neuropathy (SFN) is associated with DLB. METHODS: We studied 18 well-characterized patients with DLB (11 with autonomic dysfunction), 23 patients with nonsynucleinopathy dementia (NSD; 13 with young-onset Alzheimer disease dementia, 6 frontotemporal dementia, and 4 vascular dementia), and 25 healthy controls. All participants underwent skin biopsies from proximal (i.e., cervical) and distal (i.e., thigh and distal leg) sites to study small nerve fibers and deposits of p-syn, considered the pathologic form of α-synuclein. RESULTS: No p-syn was detected in any skin sample in patients with NSD and controls but was found in all patients with DLB. SFN was found in patients with DLB and the autonomic denervation of skin was more severe in patients with autonomic dysfunctions. CONCLUSIONS: (1) In autonomic skin nerves, p-syn is a sensitive biomarker for DLB diagnosis, helping to differentiate DLB from other forms of dementia, although this needs to be confirmed in a larger, more representative sample; and (2) skin autonomic neuropathy is part of the DLB pathology and may contribute to autonomic symptoms. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that p-syn in skin nerve fibers on skin biopsy accurately distinguishes DLB from other forms of dementia.

Multiple variants in families with amyotrophic lateral sclerosis and frontotemporal dementia related to C9orf72 repeat expansion: further observations on their oligogenic nature.

The C9orf72 repeat expansion (RE) is one of the most frequent causative mutations of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). However, it is still unclear how the C9orf72 RE can lead to a heterogeneous phenotype. Several reports have shown the coexistence of mutations in multiple ALS/FTD causative genes in the same family, suggesting an oligogenic etiology for ALS and FTD. Our aim was to investigate this phenomenon in an Italian group of ALS/FTD pedigrees carrying the C9orf72 RE. We included 11 subjects from 11 pedigrees with ALS/FTD and the C9orf72 RE. Mutation screening of FUS, SOD1 and TARDBP genes was performed by direct sequencing. A dementia-specific custom-designed targeted next-generation sequencing panel was used for screening dementia-associated genes mutations. We found genetic variants in additional ALS or dementia-related genes in four pedigrees, including the p.V47A variant in the TYROBP gene. As a group, double mutation carriers displayed a tendency toward a younger age at onset and a higher frequency of positive familiar history and of parkinsonism. Our observation supports the hypothesis that the co-presence of mutations in different genes may be relevant for the clinical expression of ALS/FTD and of their oligogenic nature.

Migraine attacks, aura, and polycythemia: a vasculoneural pathogenesis?

Headache is a frequent symptom of polycythemia. A case study of a polycythemia vera patient affected by migraines, with and without aura, who developed headache attacks with aura in association with elevated haematocrit and haemoglobin levels is presented. A vasculoneural pathogenesis is supposed.