Differential Gene Expression In Young Patients Before And After Free Tissue Transfer For Parry Romberg Disease
Jacqueline S. Israel, MD, Rebecca L. Farmer, MD, PhD, Sarah M. Lyon, MD, Kirsten A. Gunderson, BS, Jenny T. Chen, MD, Samuel O. Poore, MD, PhD, John W. Siebert, MD.
University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
Purpose: The pathophysiology of hemifacial atrophy (Parry Romberg disease) remains poorly understood. The purpose of this study was to evaluate differences in affected soft tissue gene expression in young patients with Parry Romberg before and after free tissue transfer, using each subjectís contralateral, unaffected tissue as a control.
Methods: Patients with hemifacial atrophy underwent reconstruction with a free parascapular flap. Revisions were performed in all patients 6 months postoperatively. Skin samples were obtained from the affected hemiface at the time of free tissue transfer (stage 1), and revision (stage 2). Each subject was their own control. RNA sequencing was performed using Illumina HiSeq. Reads were mapped back to the genome and differentially expressed genes were identified.
Results: Eight subjects were included, with ages ranging from 4-29 years (mean 12 years). For the 1,991 differentially expressed (DE) genes identified when stage 1 samples were compared to stage 2 (p<0.05), high resolution was noted. When all three groups were compared, stage 2 samples more closely resembled the control group. Significant pathways amongst the DE genes included protein digestion, IL-17 and TNF signaling, and immune regulation.
Conclusion: This is the first study to use internal controls to compare molecular signatures of affected tissue in young patients with Parry Romberg disease undergoing free tissue transfer. We have identified several gene pathways for ongoing study. A multi-center study incorporating fat grating as a treatment option may allow for a more nuanced understanding of the pathophysiology of this disease process and the effects of treatment.
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