Yong Oock Kim’s research while affiliated with Yonsei University Hospital and other places

Craniosynostosis (CRS) is characterized by the development of abnormal cranial suture ossification and premature fusion. Despite the identification of several associated genetic disorders, the genetic determinants of CRS remain poorly understood. In this study, we conducted integrative analyses on 225 exomes, comprising 121 CRS probands and 104 parental exomes (52 trios). These analyses encompassed de novo and pathogenic variants, and digenic combinations within haploinsufficient genes harboring rare variants. Our analysis unveils a shared molecular network between genes associated with CRS and those linked to skeletal and neurodevelopmental disorders, with a notable enrichment of deleterious variants within haploinsufficient genes. Additionally, we identified a unique digenic pair (IL6ST and TRPS1) within haploinsufficient genes that was present in 2 patients with nonsyndromic CRS but absent in parents or 1,048 population controls. In vitro experiments provided evidence that the identified missense variants were hypomorphs, and accelerated bone mineralization could result from the additive effects of diminished IL6ST and TRPS1 activities in osteoblasts. Overall, our study underscores the important role of rare variations in haploinsufficient genes and suggests that in a subset of undiagnosed patients, the CRS phenotype may arise from multiple genetic variations.

RASopathies represent a distinct class of neurodevelopmental syndromes caused by germline variants in the Ras/MAPK pathways. Recently, a novel disease‐gene association was implicated in MAPK kinase kinase kinase 4 (MAP4K4), which regulates the upstream signals of the MAPK pathways. However, to our knowledge, only two studies have reported the genotype–phenotype relationships in the MAP4K4‐related disorder. This study reports on a Korean boy harboring a novel de novo missense variant in MAP4K4 (NM_001242559:c.569G>T, p.Gly190Val), revealed by trio exome sequencing, and located in the hotspot of the protein kinase domain. The patient exhibited various clinical features, including craniofacial dysmorphism, language delay, congenital heart defects, genitourinary anomalies, and sagittal craniosynostosis. Our study expands the phenotypic association of the MAP4K4‐related disorder to include syndromic craniosynostosis, thereby providing further insights into the role of the RAS/MAPK pathways in the development of premature fusion of calvarial sutures.

Reconstructions of extensive composite scalp and cranial defects are challenging due to high incidence of postoperative infection and reconstruction failure. In such cases, cranial reconstruction and vascularized soft tissue coverage are required. However, optimal reconstruction timing and material for cranioplasty are not yet determined. Herein, we present a large skull defect with a chronically infected wound that was not improved by repeated debridement and antibiotic treatment for 3 months. It was successfully treated with anterolateral thigh (ALT) free flap transfer for wound salvage and delayed cranioplasty with a patient-specific polyetheretherketone implant. To reduce infection risk, we performed the cranioplasty 1 year after the infection had resolved. In the meantime, depression of ALT flap at the skull defect site was observed, and the midline shift to the contralateral side was reported in a brain computed tomography (CT) scan, but no evidence of neurologic deterioration was found. After the surgery, sufficient cerebral expansion without noticeable dead-space was confirmed in a follow-up CT scan, and there was no complication over the 1-year follow-up period.

Background: Although the benefits of helmet therapy for positional plagiocephaly are strongly correlated with age, the effective period remains controversial. However, most physicians agree that effective results can be obtained in patients within the age of 6 months. Owing to the characteristics of positional plagiocephaly in Koreans, many Korean patients have delayed diagnosis, and because this results in delayed onset of the helmet therapy, the outcomes remain largely underevaluated. In the management of late-diagnosed positional plagiocephaly, we aimed to determine the factors affecting the effective application of helmet therapy. Methods: We recruited 39 consecutive patients with positional plagiocephaly who received helmet therapy and completed the treatment between December 2008 and June 2016. The ages at initiation and completion of treatment, duration of daily use, initial and final absolute diagonal differences, cephalic index, and cranial vault asymmetry index (CVAI) were analysed using data retrospectively collected from the patients' medical records. Results: We identified 12 patients with late-diagnosed positional plagiocephaly, of whom 83.33% were effectively treated. The effective change in CVAI (%) was affected by age at treatment initiation (P = 0.001), initial absolute diagonal distance differences (P < 0.001), and initial CVAI (P < 0.001). Up to 9 months, a gradual change of at least 1% CVAI was attained. Treatment initiation at ages < 5.5 months was beneficial. Even at a later age, patients with an initial absolute diagonal distance difference of > 13.50 mm and initial CVAI of > 11.03% could receive effective helmet therapy. Conclusion: The efficacy of helmet therapy in late-diagnosed patients can be predicted on the basis of not only age at treatment initiation, but also initial absolute diagonal distance differences and initial CVAI. We anticipate that even patients with late-diagnosed positional plagiocephaly can expect better helmet therapy outcomes.

In article number 2000092, In Sik Yun, Jong‐Souk Yeo, and co‐workers show the quantitative relationship between nanotopography and cell spreading mediated by focal adhesions (FAs) using adipose‐derived stem cells (ASCs). Since FAs require a constant adhesive area to maintain cell attachment on nanotopography, larger FAs are supported by many smaller nanopillars that also control the spread of ASCs.

Nanotopography mimicking extracellular environments reportedly impact cell morphological changes; however, elucidating this relationship has been challenging. To control cellular responses using nanostructures, in this study, the quantitative relationship between nanotopography and cell spreading mediated by focal adhesions (FAs) is demonstrated using adipose‐derived stem cells (ASCs). The spreading of ASCs and area of FAs are analyzed for the distribution of filamentous actin and vinculin, respectively, using fluorescent images. FAs require a specific area for adhesion (herein defined as effective contact area [ECA]) to maintain cell attachment on nanopillar arrays. An ECA is the area of FAs supported by nanopillars, multiplying the area fraction (AF) of their top surface. Regarding the spreading of cells, the mean area of ASCs linearly decreases as the mean area of FAs increases. Because the area of FAs is inversely correlated to the AF of the nanopillar arrays, the spreading of cells can be quantitatively correlated with nanotopography. The results provide a conceptual framework for controlling cell behaviors to design artificial substrates for tissue‐engineering applications.

Background: Genetic factors play an important role in the pathogenesis of craniosynostosis (CRS). However, the molecular diagnosis of CRS in clinical practice is limited because of its heterogeneous etiology. Objective: To investigate the genomic landscape of CRS in a Korean cohort and also to establish a practical diagnostic workflow by applying targeted panel sequencing. Methods: We designed a customized panel covering 34 CRS-related genes using in-solution hybrid capture method. We enrolled 110 unrelated Korean patients with CRS, including 40 syndromic and 70 nonsyndromic cases. A diagnostic pipeline was established by combining in-depth clinical reviews and multiple bioinformatics tools for analyzing single-nucleotide variants (SNV)s and copy number variants (CNV)s. Results: The diagnostic yield of the targeted panel was 30.0% (33/110). Twenty-five patients (22.7%) had causal genetic variations resulting from SNVs or indels in 9 target genes (TWIST1, FGFR3, TCF12, ERF, FGFR2, ALPL, EFNB1, FBN1, and SKI, in order of frequency). CNV analysis identified 8 (7.3%) additional patients with chromosomal abnormalities involving 1p32.3p31.3, 7p21.1, 10q26, 15q21.3, 16p11.2, and 17p13.3 regions; these cases mostly presented with syndromic clinical features. Conclusion: The present study shows the wide genomic landscape of CRS, revealing various genetic factors for CRS pathogenesis. In addition, the results demonstrate that an efficient diagnostic workup using target panel sequencing provides great clinical utility in the molecular diagnosis of CRS.

Purpose: Relaxin (RLX) is a transforming growth factor-β1 (TGF-β1) antagonist that is believed to function as a potent collagen re-arranger and a major suppressor of extracellular matrix components. Adenoviruses (Ads) are accepted vectors for cancer gene therapy. However, repeated treatments of Ad are limited by short-term biological activity in vivo. The efficacy of sustained RLX expression to scar remodeling was assessed using an injectable alginate gel-matrix system. Materials and methods: Pig scar tissue was treated with relaxin-expressing Ad loaded in alginate gel (gel/Ad-RLX). Surface areas, color, and pliability of scars were compared, and various factors influencing scar formation and collagen arrangement were analyzed. Results: Gel/Ad-RLX decreased scar size, color index, and pliability. Immunohistochemistry showed decreased levels of major extracellular matrix proteins in the gel/Ad-RLX-treated group. Furthermore, treatment with gel/Ad-RLX reduced expression of tissue inhibitor of metalloproteinase-1 and alpha-smooth muscle actin and markedly increased expression of matrix metalloproteinase-1 in pig scar tissues. Gel/Ad-RLX also significantly downregulated TGF-β1 and upregulated TGF-β3 mRNAs in pig scar tissues. Conclusion: These results support a prominent role for RLX in scar remodeling and suggest that gel/Ad-RLX may have therapeutic effects on scar formation.