Whole transcriptome analysis of unmutated sporadic ALS patients' peripheral blood reveals phenotype-specific gene expression signature

Amyotrophic lateral sclerosis (ALS) is an adult neurodegenerative disorder. According to clinical criteria, ALS patients can be classified into eight subgroups: classic, bulbar, pyramidal, pure lower motor neuron, flail arm, pure upper motor neuron, flail leg, and respiratory. There are no well-established molecular biomarkers for early diagnosis, prognosis, and progression monitoring of this fatal disease. Classification based on clinical phenotypes could be associated with peculiar gene expression patterns shaped during lifespan, allowing the identification of specific sporadic ALS (sALS) subtypes with less heterogeneous clinical and biological features. Our objective was to define a phenotype-specific transcriptomic signature of distinct ALS phenotypes, and lay the foundation for biomarkers development. We characterized 48 sALS patients by clinical and paraclinical parameters, and subdivided them in "Classic" (n = 12), "Bulbar" (n = 10), "Flail Arm" (n = 7), "Flail Leg" (n = 10) and "Pyramidal" (n = 9) phenotypes. RNAs extracted from patients' PBMCs and 19 controls were sequenced. Our analysis allowed the visualization of gene expression differential clusters between patients and controls. Interestingly, only one gene (Y3_RNA, a misc_RNA component of the Ro60 ribonucleoprotein involved in cellular response to interferon-alpha) was upregulated at different levels across all phenotypes, whereas other genes appeared phenotype-specific. The work proposed stress the innovative view of ALS as a multi-systemic disorder rather than a pure motor neuron-associated and 'neurocentric' pathology. The possibility to cluster ALS patients based on their molecular signature pave the way for future personalized clinical trials and early diagnosis.

Neurophysiological Alterations of the Visual Pathway in Posterior Cortical Atrophy: Systematic Review and a Case Series

Background

The clinical features of posterior cortical atrophy (PCA), a rare condition often caused by Alzheimer's disease, have been recently defined, while little is known about its neurophysiological correlates.

Objective

To describe neurophysiological alterations of the visual pathway as assessed using visual field test (VF), visual evoked potentials (VEP), and electroretinogram (ERG) in PCA patients.

Methods

Studies reporting VF, VEPs, and ERG in PCA patients were selected according PRISMA method. Of the 323 articles that emerged from the literature, 17 included the outcomes of interest. To these data, we added those derived from a patient cohort enrolled at our clinic.

Results

The literature review included 140 patients, half of them (50%) presented with homonymous hemianopia or quadrantanopia. VEPs were available in 4 patients (2 normal findings, 1 decreased amplitude, and 1 increased latency) and ERG in 3 patients (substantially normal findings). Our case series included 6 patients, presenting with homonymous lateral hemianopia in 50% and contralateral cortical atrophy. VEPs showed normal amplitude in 66-83% according to the stimulation check, and increased latency in 67% in absence of myelin damage on MRI. Latency was increased in both eyes in 50% and only on one side in the other 50%. Such alterations were observed in patients with more severe and symmetric atrophy. ERG showed normal findings.

Conclusions

Neurophysiological investigations of the visual pathway in PCA are almost absent in literature. Alterations involve both amplitude and latency and can be also monocular. A multiple-point involvement of the optical pathway can be hypothesized.