Biallelic PI4KA variants cause a novel neurodevelopmental syndrome with hypomyelinating leukodystrophy

Phosphoinositides are lipids that play a critical role in processes such as cellular signalling, ion channel activity and membrane trafficking. When mutated, several genes that encode proteins that participate in the metabolism of these lipids give rise to neurological or developmental phenotypes. PI4KA is a phosphoinositide kinase that is highly expressed in the brain and is essential for life. Here we used whole exome or genome sequencing to identify 10 unrelated patients harbouring biallelic variants in PI4KA that caused a spectrum of conditions ranging from severe global neurodevelopmental delay with hypomyelination and developmental brain abnormalities to pure spastic paraplegia. Some patients presented immunological deficits or genito-urinary abnormalities. Functional analyses by western blotting and immunofluorescence showed decreased PI4KA levels in the patients’ fibroblasts. Immunofluorescence and targeted lipidomics indicated that PI4KA activity was diminished in fibroblasts and peripheral blood mononuclear cells. In conclusion, we report a novel severe metabolic disorder caused by PI4KA malfunction, highlighting the importance of phosphoinositide signalling in human brain development and the myelin sheath.

[Novel therapies in neurometabolic diseases: the importance of early intervention]

INTRODUCTION

Individually, neurometabolic diseases are ultra rare, but for some of them there is an effective treatment.

DEVELOPMENT

Several recent therapeutic advances are reviewed. Today, the possibilities of treatment for lysosomal diseases have improved. In recent years the use of enzyme replacement therapy has become more widely extended to treat mucopolysaccharidosis type IVA (Morquio A), mucopolysaccharidosis type VII (Sly syndrome), lysosomal acid lipase deficiency and alpha-mannosidosis. It has been proven that very early treatment of mucopolysaccharidoses can change their natural course. Intrathecal enzyme replacement therapy is being tried in some mucopolysaccharidoses with cognitive involvement, in an attempt to halt neurodegeneration. Very positive results have been obtained with genetically modified autotransplants in late-onset infantile metachromatic leukodystrophy and research is being conducted on other pathologies (mucopolysaccharidosis type III, X-linked adrenoleukodystrophy). Novel outcomes are also being achieved in the treatment of some encephalopathies that are sensitive to vitamins or cofactors: triple therapy in pyridoxine dependency, treatment with thiamine for some subacute encephalopathies with involvement of the basal ganglia, treatment with folinic acid for children with cerebral folate deficiency, or treatment with cyclic pyranopterin monophosphate in molybdenum cofactor deficiency type A.

CONCLUSIONS

As neuropaediatricians we must update our knowledge, especially in the case of treatable neurometabolic pathologies, since early treatment can change their prognosis significantly.

Procalcitonin, a high acute phase reactant in antiepileptic hypersentivity syndrome in pediatric age

Antiepileptic hypersensitivity syndrome (AHS) is a potentially life-threatening syndrome in pediatric cases. It is associated with aromatic anticonvulsivant drugs and others antibiotics with or without associated reactivation of virus. The pathogenesis of the process is not clear. Clinical feature of this syndrome include cutaneous reactions, fever and lymphadenopathies, but different organs can be involved. In laboratory analyses we can find leucocytosis, eosinophilia, and increase in transaminase levels. Significant elevation of procalcitonin (PCT) has been described in two adults patients. This study we report two cases of a 14-year-old male and a 13-year-old female with a AHS and a high level of the PCT. These are the first cases described in pediatric age. Establishing a diagnosis of AHS is important to avoid the use of the involved drug. The treatment is based on the withdrawal of the drugs that are supposed and if there is no improvement or a deterioration of the patient, the use of systemic corticosteroids is often useful.