Biallelic truncating variants in ATP9A cause a novel neurodevelopmental disorder involving postnatal microcephaly and failure to thrive.

BACKGROUND: Genes implicated in the Golgi and endosomal trafficking machinery are crucial for brain development, and mutations in them are particularly associated with postnatal microcephaly (POM). METHODS: Exome sequencing was performed in three affected individuals from two unrelated consanguineous families presenting with delayed neurodevelopment, intellectual disability of variable degree, POM and failure to thrive. Patient-derived fibroblasts were tested for functional effects of the variants. RESULTS: We detected homozygous truncating variants in ATP9A. While the variant in family A is predicted to result in an early premature termination codon, the variant in family B affects a canonical splice site. Both variants lead to a substantial reduction of ATP9A mRNA expression. It has been shown previously that ATP9A localises to early and recycling endosomes, whereas its depletion leads to altered gene expression of components from this compartment. Consistent with previous findings, we also observed overexpression of ARPC3 and SNX3, genes strongly interacting with ATP9A. CONCLUSION: In aggregate, our findings show that pathogenic variants in ATP9A cause a novel autosomal recessive neurodevelopmental disorder with POM. While the physiological function of endogenous ATP9A is still largely elusive, our results underline a crucial role of this gene in endosomal transport in brain tissue.

Identification and characterization of a phage display-derived peptide for orthopoxvirus detection.

Fast and reliable diagnostic assays are required for a resilient detection of clinical infections or biothreat-relevant pathogens. While PCR has proven to be the gold standard for nucleic acid detection, the identification of pathogen particles is still challenging and depends on the availability of well-characterized, chemically stable, and selective recognition molecules. Here, we report the screening of a phage display random peptide library for vaccinia virus-binding peptides. The identified peptide was extensively characterized using peptide-probe ELISA, surface plasmon resonance, nLC-MS/MS, Western Blot, peptide-based immunofluorescence assay, and electron microscopy. Following identification, the phage-free, synthetic peptide, designated αVACVpep05, was shown to bind to vaccinia virus and other orthopoxviruses. We can demonstrate that the highly conserved orthopoxvirus surface protein D8 is the interaction partner of αVACVpep05, thus enabling the peptide to bind to other orthopoxviruses, including cowpox virus and monkeypox virus, viruses that cause clinically relevant zoonotic infections in humans. The process of phage display-mediated peptide identification has been optimized intensively, and we provide recommendations for the identification of peptides suitable for the detection of further pathogens. The peptide described here was critically characterized and seems to be a promising reagent for the development of diagnostic platforms for orthopoxviruses. We believe that our results will help to promote the development of alternative, nonantibody-based synthetic detection molecules for further pathogens.