CRISPR-Based Gene Editing Techniques in Pediatric Neurological Disorders

The emergence of gene editing technologies offers a unique opportunity to develop mutation-specific treatments for pediatric neurological disorders. Gene editing systems can potentially alter disease trajectory by correcting dysfunctional mutations or therapeutically altering gene expression. Clustered regularly interspaced short palindromic repeats (CRISPR)-based approaches are attractive gene therapy platforms to personalize treatments because of their specificity, ease of design, versatility, and cost. However, many such approaches remain in the early stages of development, with ongoing efforts to optimize editing efficiency, minimize unintended off-target effects, and mitigate pathologic immune responses. Given the rapid evolution of CRISPR-based therapies, it is prudent for the clinically based child neurologist to have a conceptual understanding of what such therapies may entail, including both benefits and risks and how such therapies may be clinically applied. In this review, we describe the fundamentals of CRISPR-based therapies, discuss the opportunities and challenges that have arisen, and highlight preclinical work in several pediatric neurological diseases.

Neuronal sphingolipidoses: Membrane lipids and sphingolipid activator proteins regulate lysosomal sphingolipid catabolism

Glycosphingolipids and sphingolipids of cellular plasma membranes (PMs) reach luminal intra-lysosomal vesicles (LVs) for degradation mainly by pathways of endocytosis. After a sorting and maturation process (e.g. degradation of sphingomyelin (SM) and secretion of cholesterol), sphingolipids of the LVs are digested by soluble enzymes with the help of activator (lipid binding and transfer) proteins. Inherited defects of lipid-cleaving enzymes and lipid binding and transfer proteins cause manifold and fatal, often neurodegenerative diseases. The review summarizes recent findings on the regulation of sphingolipid catabolism and cholesterol secretion from the endosomal compartment by lipid modifiers, an essential stimulation by anionic membrane lipids and an inhibition of crucial steps by cholesterol and SM. Reconstitution experiments in the presence of all proteins needed, hydrolase and activator proteins, reveal an up to 10-fold increase of ganglioside catabolism just by the incorporation of anionic lipids into the ganglioside carrying membranes, whereas an additional incorporation of cholesterol inhibits GM2 catabolism substantially. It is suggested that lipid and other low molecular modifiers affect the genotype-phenotype relationship observed in patients with lysosomal diseases.

GM2-Gangliosidosis (Sandhoff and Tay Sachs disease): Diagnosis and Neuroimaging Findings (An Iranian Pediatric Case Series)

OBJECTIVE

GM2-Gangliosidosis disease is a rare autosomal recessive genetic disorder that includes two disorders (Tay-Sachs and Sandhoff disease).These disorders cause a progressive deterioration of nerve cells and inherited deficiency in creating hexosaminidases A, B, and AB.

MATERIALS & METHODS

Patients who were diagnosed withGM2-Gangliosidosis in the Neurology Department of Mofid Children's Hospital in Tehran, Iran from October 2009 to February 2014were included in our study. The disorder was confirmed by neurometabolic and enzyme level detection of hexosaminidases A, B, and AB in reference to Wagnester Laboratory in Germany. We assessed age, gender, past medical history, developmental status, clinical manifestations, and neuroimaging findings of 9 patients with Sandhoff disease and 9 with Tay Sachs disease.

RESULTS

83% of our patients were the offspring of consanguineous marriages. All of them had a developmental disorder as a chief complaint. 38%of patients had a history of developmental delay or regression and 22% had seizures. The patients with Sandhoff and Tay Sachs disease were followed for approximately 5 years and the follow-up showed all patients were bedridden or had expired due to refractory seizures, pneumonia aspiration, or swallowing disorders. Neuro-imaging findings included bilateral thalamic involvement, brain atrophy, and hypo myelination in near half of our patients (48%).

CONCLUSION

According to the results of this study, we suggest that cherry-red spots, hyperacusis, refractory seizures, and relative parents in children with developmental delay and/or regression should be considered for assessment of GM2-Gangliosidosis disease.