Congenital Disorders of Autophagy: What a Pediatric Neurologist Should Know

Abstract

Autophagy is a fundamental and conserved intracellular pathway that mediates the degradation of macromolecules and organelles in lysosomes. Proper autophagy function is important for central nervous system development and neuronal function. Over the last 5 years, several single gene disorders of the autophagy pathway have emerged: -associated Vici syndrome,-associated β-propeller protein-associated neurodegeneration, -associated autosomal-recessive spinocerebellar ataxia 20,-associated autosomal-recessive ataxia syndrome, -associated childhood-onset neurodegeneration, and several forms of the hereditary spastic paraplegias. This novel and evolving group of disorders is characterized by prominent central nervous system involvement leading to brain malformations, developmental delay, intellectual disability, epilepsy, movement disorders, and neurodegeneration. Predominant involvement of the long white matter tracts and the cerebellum are anatomic and imaging hallmarks, with common findings that include a thinning of the corpus callosum and cerebellar hypoplasia or atrophy. A storage disease phenotype by clinical or imaging criteria is present in some diseases. Most congenital disorders of autophagy are progressive and over time involve pathology in multiple brain regions. This review provides a detailed clinical, imaging and genetic characterization of congenital disorders of autophagy and highlights the importance of this pathway for childhood-onset neurological diseases.

Novel insights into the clinical and molecular spectrum of congenital disorders of autophagy

“…Over the last decades, autophagy has been shown to be involved in the turnover of different cargo in mammalian cells including mitochondria (‘mitophagy’), the endoplasmic reticulum (‘reticulophagy’), peroxisomes (‘pexophagy’), lysosomes (‘lysophagy’), lipid droplets (‘lipophagy’), glycogen (‘glycophagy’), iron (‘ferritinophagy’) and invading pathogens (‘xenophagy’) . Single‐gene disorders of the autophagy pathway, so‐called congenital disorders of autophagy , are an emerging group of inborn errors of metabolism . Defective autophagy has also been implicated in a myriad of sporadic and other inherited diseases including major neurodegenerative diseases and lysosomal storage disorders .…”

EPG5 Variants with Modest Functional Impact Result in an Ameliorated and Primarily Neurological Phenotype in a 3.5-Year-Old Patient with Vici Syndrome

“…Vici syndrome (OMIM 242840) is a severe, multisystem disorder presenting with agenesis of the corpus callosum (ACC), oculocutaneous hypopigmentation, bilateral cataracts, combined immunodeficiency, hypertrophic, or dilated cardiomyopathy. [1][2][3][4][5] Nearly all patients reported to date also showed profound early-onset global developmental delay, postnatal microcephaly, and failure to thrive, adding these to the eight cardinal features of Vici syndrome (►Table 1). Other less common manifestations include facial dysmorphism, sensorineural hearing loss, optic nerve atrophy, hypotonia, myopathy, and seizures.…”

Novel genetic features of human and mouse Purkinje cell differentiation defined by comparative transcriptomics

“…PCs are particularly affected in mice conditionally mutant for autophagy genes Atg5 or Atg7 (54,55). In humans, a handful of congenital disorders of autophagy have been described with mutations in SNX14, ATG5, and SQSTM1/p62 affecting the cerebellum (56). Like mitochondria genes, our findings define P0-P7 as the time when autophagy genes are upregulated during mouse PC development.…”