Abstract:

Somatic mosaic mutations in several genes including in the G-protein coupled receptor subunit GNAQ are associated with vascular anomalies such as port-wine stains and Sturge-Weber syndrome. The downstream molecular changes at the mRNA and protein level resulting from these mutations remain uncertain, resulting in a lack of treatments. We utilized a first-of-its-kind, multimodal approach to address gaps in knowledge. First, we performed high-resolution whole exome sequencing to determine the genotype of affected skin in four pediatric patients. We then coupled genotyping to novel deep clinical phenotyping, including clinical images, colorimetric analysis, and optical coherence tomography. Finally, we established an experimental and computational pipeline for spatial transcriptomics to determine differential gene expression in affected skin compared to anatomically matched normal skin. High-resolution sequencing primed for low variant allele frequency detection confirmed the most common somatic mosaic variant (GNAQ R183Q) without co-occurring mutations. Deep clinical phenotyping, including OCT imaging, revealed a statistically significant increase in vessel diameter and density in affected skin but not in anatomically matched normal skin. Unbiased spatial transcriptomics yielded high quality data, establishing the utility of this method; the proportion of reads confidently mapped to the genome was ≥ 90% for all samples, and on average 17,602 genes were detected per sample (out of ~25,000 expected in the human genome) with at least 5 mRNAs. Our results reveal novel and important findings to guide the development of targeted treatment, including unexpected alterations in MAP kinase pathway members and endothelial sheer stress regulators.

Financial Disclosure:
No current or relevant financial relationships exist.

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Aman Prasad, MD, PhD