Braun, Daniela A., Shril, Shirlee, Sinha, Aditi, Schneider, Ronen, Tan, Weizhen, Ashraf, Shazia, Hermle, Tobias, Jobst-Schwan, Tilman, Widmeier, Eugen, Majmundar, Amar J., Daga, Ankana, Warejko, Jillian K., Nakayama, Makiko, Schapiro, David, Chen, Jing, Airik, Merlin, Rao, Jia, Schmidt, Johanna Magdalena, Hoogstraten, Charlotte A., Hugo, Hannah, Meena, Jitendra, Lek, Monkol, Laricchia, Kristen M., Bagga, Arvind, and Hildebrandt, Friedhelm
INTRODUCTION: Galloway-Mowat syndrome (GAMOS) is a phenotypically heterogeneous disorder characterized by neurodevelopmental defects combined with renal-glomerular disease, manifesting with proteinuria. To identify additional monogenic disease causes, we subjected three affected siblings of an Indian family with GAMOS to mutation analysis. METHODS: We performed whole exome sequencing (WES), linkage analysis, and homozygosity mapping. RESULTS: Applying established criteria for variant filtering, we identify a novel homozygous splice site mutation in the gene WDR4 as the likely disease-causing mutation in this family. In line with previous reports, we observe growth deficiency, microcephaly, developmental delay, and intellectual disability as phenotypic features resulting from WDR4 mutations. However, the newly identified allele additionally gives rise to proteinuria and nephrotic syndrome, a phenotype that was never reported in patients with WDR4 mutations. CONCLUSION: Our data expand the phenotypic spectrum of WDR4 mutations by demonstrating that, depending on the specific mutated allele, a renal phenotype may be present. This finding suggests that GAMOS may occupy a phenotypic spectrum with other microcephalic diseases. Furthermore, WDR4 is an additional example of a gene that encodes a tRNA modifying enzyme and gives rise to GAMOS, if mutated. Our findings thereby support the recent observation that, like neurons, podocytes of the renal glomerulus are particularly vulnerable to cellular defects resulting from altered tRNA modifications.