Bi-allelic variants in HOPS complex subunit VPS41 cause cerebellar ataxia and abnormal membrane trafficking

Membrane trafficking is a complex, essential process in eukaryotic cells responsible for protein transport and processing. Deficiencies in vacuolar protein sorting (VPS) proteins, key regulators of trafficking, cause abnormal intracellular segregation of macromolecules and organelles and are linked to human disease. VPS proteins function as part of complexes such as the homotypic fusion and vacuole protein sorting (HOPS) tethering complex, composed of VPS11, VPS16, VPS18, VPS33A, VPS39 and VPS41. The HOPS-specific subunit VPS41 has been reported to promote viability of dopaminergic neurons in Parkinson’s disease but to date has not been linked to human disease. Here, we describe five unrelated families with nine affected individuals, all carrying homozygous variants in VPS41 that we show impact protein function. All affected individuals presented with a progressive neurodevelopmental disorder consisting of cognitive impairment, cerebellar atrophy/hypoplasia, motor dysfunction with ataxia and dystonia, and nystagmus. Zebrafish disease modelling supports the involvement of VPS41 dysfunction in the disorder, indicating lysosomal dysregulation throughout the brain and providing support for cerebellar and microglial abnormalities when vps41 was mutated. This provides the first example of human disease linked to the HOPS-specific subunit VPS41 and suggests the importance of HOPS complex activity for cerebellar function.

Passive smoking and nonrecurrent acute otitis media in children

INTRODUCTION

It remains uncertain whether passive smoking is a risk factor (RF) for nonrecurrent acute otitis media (AOM). The aim of this study was to evaluate whether exposure to second-hand smoke at home increased the prevalence of an isolated single episode of nonrecurrent AOM in children.

METHODS AND MATERIAL

We performed a cross-sectional study with 192 children younger than 3 years who were seen at a general pediatric clinic. A questionnaire was used to quantify the exposure to cigarette smoke at home and to assess other RFs for AOM. The diagnosis of AOM was made by pediatricians using otoscopy. The results of the associations were reported by prevalence ratios with 95% confidence intervals. Multiple logistic regression was used to investigate the role of confounding variables among other potential RFs and passive smoking.

RESULTS

The prevalence ratio of an isolated single episode of nonrecurrent AOM between patients exposed and those not exposed to passive smoking was 0.82 (0.67 to 1.02). In logistic regression, any RF changed the main association significantly.

CONCLUSION

Exposure to passive smoking did not change the prevalence of an isolated single episode of nonrecurrent AOM in children.