Calcific tendinitis of the shoulder in the Korean population: demographics and its relation with coexisting rotator cuff tear

Background@#To evaluate the demographics, clinical and radiographic features of calcific tendinitis of the shoulder in the Korean population, specifically focusing on the incidence of coexisting rotator cuff tear. @*Methods@#Between October 2014 and January 2015, we performed a prospective multicenter study with 506 patients from 11 training hospitals in Korea. We collected data of demographics and radiographic analysis based on simple radiographs, clinical assessments based on visual analog scale (VAS) and the American Shoulder Elbow Surgeons (ASES) score, and treatment modalities that are used currently. We also evaluated coexisting rotator cuff tear by ultrasonography (US) or magnetic resonance imaging (MRI) images. @*Results@#There were 402 female patients (79%) with mean age of 55 years (range, 31–87 years). Mean duration of symptoms was 16 months. Mean size of calcific materials was 11.4 mm (range, 0–35 mm). Mean value of VAS and ASES scores were 6.5 (range, 1–10) and 47 (range, 8–95), respectively. Of 383 patients (76%), 59 (15%) had rotator cuff tear including 15 full-thickness tears on US or MRI. Patients with rotator cuff tears were significantly associated with older age, recurrent symptoms, menstrual disorders in females, and having undergone calcification removal surgery and rotator cuff repair (all p<0.05). @*Conclusions@#This study reported demographic, radiographic, and clinical features of calcific tendinitis of the shoulder in Korean population, which were not different from those of Western population. Coexisting rotator cuff tear was found with 15% incidence in this large series, suggesting that further radiographic study to evaluate rotator cuff tear might be needed in some calcific tendinitis patients of older age and presenting with recurrent symptoms.

Calcific tendinitis of the shoulder in the Korean population: demographics and its relation with coexisting rotator cuff tear

Background@#To evaluate the demographics, clinical and radiographic features of calcific tendinitis of the shoulder in the Korean population, specifically focusing on the incidence of coexisting rotator cuff tear. @*Methods@#Between October 2014 and January 2015, we performed a prospective multicenter study with 506 patients from 11 training hospitals in Korea. We collected data of demographics and radiographic analysis based on simple radiographs, clinical assessments based on visual analog scale (VAS) and the American Shoulder Elbow Surgeons (ASES) score, and treatment modalities that are used currently. We also evaluated coexisting rotator cuff tear by ultrasonography (US) or magnetic resonance imaging (MRI) images. @*Results@#There were 402 female patients (79%) with mean age of 55 years (range, 31–87 years). Mean duration of symptoms was 16 months. Mean size of calcific materials was 11.4 mm (range, 0–35 mm). Mean value of VAS and ASES scores were 6.5 (range, 1–10) and 47 (range, 8–95), respectively. Of 383 patients (76%), 59 (15%) had rotator cuff tear including 15 full-thickness tears on US or MRI. Patients with rotator cuff tears were significantly associated with older age, recurrent symptoms, menstrual disorders in females, and having undergone calcification removal surgery and rotator cuff repair (all p<0.05). @*Conclusions@#This study reported demographic, radiographic, and clinical features of calcific tendinitis of the shoulder in Korean population, which were not different from those of Western population. Coexisting rotator cuff tear was found with 15% incidence in this large series, suggesting that further radiographic study to evaluate rotator cuff tear might be needed in some calcific tendinitis patients of older age and presenting with recurrent symptoms.

Essential Elements for Establishing Clinical Next-generation Sequencing Testing

Over the past decade, next-generation sequencing (NGS) has evolved at an astonishing pace and has revolutionized clinical medicine as well as genomics research. The rapid advancements in NGS technologies have been accompanied by accumulating evidence of the analytical and clinical validity, and clinical utility of NGS. NGS is used worldwide. This review provides medical technicians and laboratory physicians with the essential elements for establishing clinical NGS testing. Here the authors briefly describe the advantages and drawbacks of currently available NGS platforms, potential sources of error in NGS workflow, and reference materials.

Evaluation of Inferior Capsular Laxity in Patients with Atraumatic Multidirectional Shoulder Instability with Magnetic Resonance Arthrography

OBJECTIVE: To compare inferior capsular redundancy by using magnetic resonance arthrography (MRA) images in patients with multidirectional instability (MDI) of the shoulder and control subjects without instability and thereby develop a screening method to identify the presence of shoulder MDI. MATERIALS AND METHODS: The MRA images of patients with MDI of the shoulder (n = 65, 57 men, 8 women; mean age, 24.5 years; age range, 18–42 years) treated over an eight-year period were retrospectively reviewed; a control group (n = 65, 57 men, 8 women; mean age, 27.4 years; age range, 18–45 years) without instability was also selected. The inferior capsular redundancy was measured using a new method we named the glenocapsular (GC) ratio method. MRA images of both groups were randomly mixed together, and two orthopedic surgeon reviewers measured the cross-sectional areas (CSAs) and sagittal capsule-head ratios on oblique sagittal images, as well as the axial capsule-head ratios on axial images and GC ratios on oblique coronal images. RESULTS: The CSAs and GC ratios were significantly higher in patients than in controls (both, p 1.42 was found to be most suggestive of MDI of the shoulder, owing to its high sensitivity (92.3%) and specificity (89.2%). CONCLUSION: GC ratio can be easily measured and used to accurately screen for MDI of the shoulder.

Reducing the Reporting Time by Improving Laboratory Processing for Inpatient Routine Chemistry Tests

BACKGROUND: The returning time of inpatient specimen analysis is usually slow because phlebotomists deliver all the collected specimens at the end of their work cycle. In addition, manual specimen reception further delays the reporting time and imposes a heavy workload on the technical staff, thus compromising effectiveness. Therefore, we have created an automated specimen reception system to tackle testing delays and enhance the efficiency and quality of specimen collection and handling. METHODS: In May 2015, the pre-analytical processing of inpatient samples was renovated. We automated the specimen reception in parallel with barcode printing and introduced pneumatic tubes to deliver samples for routine chemistry tests. We compared the reporting time of the automated system with that of the manual system and analyzed the distribution pattern of the specimens according to handling time. RESULTS: The median reporting time was advanced by 41 minutes, from 09:33 AM to 08:52 AM for the manual and automated reception, respectively. Moreover, with the reduction in hands-on time, the blood specimens reached the laboratory immediately after phlebotomy, thereby improving the processing efficiency by spreading out the interval during which the specimens arrived in the laboratory. Additionally, the new system allowed the identification of the phlebotomist who collected the specimens and tracking the specimens from collection to test result. CONCLUSIONS: With the introduction of our automatic reception system, the reporting time was considerably reduced. Therefore, the satisfaction of the clinician and the technical staff was improved.

Germline Variants in MLH1, MSH2, and MSH6 in Korean Patients with Lynch Syndrome

BACKGROUND: The phenotypic and genetic spectrum of Lynch syndrome (LS) seems to differ according to ethnicity. The aim of this study was to investigate the clinical, pathological, and genetic features of LS in a large sample of Korean patients. METHODS: We enrolled a total of 232 patients who fulfilled the revised Bethesda criteria (81%, 232/286) from 286 individuals who underwent genetic screening for LS (MLH1, MSH2, and MSH6 sequencing) in the Samsung Medical Center in Korea from 2004 to 2015. Histopathologic findings, microsatellite instability data, and clinical information were collected. RESULTS: We identified 61 different pathogenic or likely pathogenic variants (39 in MLH1, 20 in MSH2, and 2 in MSH6), including 4 novel variants, in 101 unrelated Korean patients (101/232, 44%). When multiple tumor manifestations in a single patient were individually considered, there were 285 cancers recorded from 232 cases. A diverse spectrum of tumors, including colorectal cancer, endometrial cancer, stomach cancer, and ovary cancer, was observed. Patients with genetic alterations were more closely associated with a family history of cancers, double primary cancers, and the development of secondary neoplasms than patients without genetic alterations (P < 0.0001, P=0.0052, and P=0.0010, respectively). CONCLUSIONS: We report the distribution of pathogenic variants in MLH1, MSH2, and MSH6, as well as the tumor spectrum, in a large sample of Korean patients with LS. Genetic testing could be an effective stratification strategy for surveillance of LS. This study sheds light on the genetic features of Asian patients with LS.

A Comparison between Open Reduction/Internal Fixation and Minimally Invasive Plate Osteosynthesis Using a 3-Dimensional Printing Model for Displaced Clavicular Fractures / 대한정형외과학회잡지

PURPOSE: This study was performed to compare between open reduction/internal fixation (ORIF) and minimally invasive plate osteosynthesis (MIPO) using a 3-dimensional printing model for displaced clavicular fractures. MATERIALS AND METHODS: In a retrospective study, we compared the outcomes of 21 patients treated with MIPO (Group A) with those of 22 patients treated with ORIF (Group B) between January 2013 and December 2015. After the operation, bone union was evaluated using X-ray every 4 weeks. The radiologic outcome (bone union), functional outcome (Korean shoulder scale [KSS], The University of California Los Angeles [UCLA] score), scar length, and degree of satisfaction were evaluated. RESULTS: The mean time to union was 12.1 weeks in Group A and 12.8 weeks in Group B (p=0.524). There was no significant difference in the KSS score and UCLA score between the two groups (p=0.478, p=0.698). The mean length of scar was 4.9 cm (medial 2.6 cm, lateral 2.3 cm) in Group A and 9.7 cm in Group B (p=0.001), and Group A was more satisfied than Group B with respect to scarring (p=0.001). Nonunion developed in one case in each group. Five patients in Group B had skin numbness (1 in Group A, p=0.038). CONCLUSION: There were no significant differences in the radiologic and functional results between the two groups with respect to displaced clavicle shaft fracture. However, scar satisfaction was higher in MIPO than in ORIF.

Performance Evaluation of ADVIA Centaur XPT

We have evaluated the performance of a recently developed immunoassay analyzer, ADVIA Centaur XPT (Siemens, Germany). Precision, linearity, and comparison studies were performed according to the CLSI guidelines. The test items evaluated were ferritin, folate, human epidermal growth factor receptor 2/neu, homocysteine, vitamin B₁₂, B-type natriuretic peptide, creatine kinase–myocardial band, myoglobin, procalcitonin, troponin I. Bio-Rad control materials, linearity materials, and patients' samples were used for the evaluation. For the correlation study, ADVIA Centaur XP (Siemens) were used as comparative methods. The total coefficients of variations (CVs) of the analytes were between 2.5% and 7.0%. The results of linearity evaluation were also acceptable for the range tested. Correlations with comparative methods were good. The overall analytical performance of ADVIA Centaur XPT is acceptable for the immunology analyzer. Therefore, ADVIA Centaur XPT is expected to be widely used.

The First Korean Family With Hereditary Gelsolin Amyloidosis Caused by p.D214Y Mutation in the GSN Gene

Hereditary gelsolin amyloidosis (HGA) is an autosomal dominant hereditary disease characterized by corneal lattice dystrophy, peripheral neuropathy, and cutis laxa. So far, no Korean patients with HGA have been reported. A 58-yr-old man presented with involuntary facial twitching, progressive bilateral facial weakness, and tongue atrophy. His mother, maternal uncle, two sisters, and son suffered from the same symptoms. Electrophysiological studies revealed signs of chronic denervation in the cervical and lumbar regions, mild sympathetic autonomic dysfunction, and bilateral facial nerve dysfunction. Diagnostic whole-exome sequencing (WES) revealed a p.D214Y heterozygous mutation in the gelsolin gene in affected members. We present the first report of a Korean family with HGA diagnosed by WES. WES facilitated a clinical diagnosis of HGA in patients with undiagnosed neuropathies.

Germline TP53 Mutation and Clinical Characteristics of Korean Patients With Li-Fraumeni Syndrome

BACKGROUND: Little is known of the mutation and tumor spectrum of Korean patients with Li-Fraumeni syndrome (LFS). Owing to the rarity of LFS, few cases have been reported in Korea thus far. This study aimed to retrospectively review the mutations and clinical characteristics of Korean patients with LFS. METHODS: TP53 mutation was screened in 89 unrelated individuals at the Samsung Medical Center in Korea, from 2004 to 2015. Six additional mutation carriers were obtained from the literature. RESULTS: We identified nine different mutations in 14 Korean patients (male to female ratio=0.3:1). Two such frameshift mutations (p.Pro98Leufs*25, p.Pro27Leufs*17) were novel. The recurrent mutations were located at codons 31 (n=2; p.Val31Ile), 175 (n=3; p.Arg175His), and 273 (n=4; p.Arg273His and p.Arg273Cys). The median age at the first tumor onset was 25 yr. Ten patients (71%) developed multiple primary tumors. A diverse spectrum of tumors was observed, including breast (n=6), osteosarcoma (n=4), brain (n=4), leukemia (n=2), stomach (n=2), thyroid (n=2), lung (n=2), skin (n=2), bladder (n=1), nasal cavity cancer (n=1), and adrenocortical carcinoma (n=1). CONCLUSIONS: There was considerable heterogeneity in the TP53 mutations and tumor spectrum in Korean patients with LFS. Our results suggest shared and different LFS characteristics between Caucasian and Korean patients. This is the first report on the mutation spectrum and clinical characteristics from the largest series of Korean LFS patients.

Adeno-Associated Virus 2-Mediated Hepatocellular Carcinoma is Very Rare in Korean Patients

BACKGROUND: The incidence and etiology of hepatocellular carcinoma (HCC) vary widely according to race and geographic regions. The insertional mutagenesis of adeno-associated virus 2 (AAV2) has recently been considered a new viral etiology of HCC. The aim of this study was to investigate the frequency and clinical characteristics of AAV2 in Korean patients with HCC. METHODS: A total of 289 unrelated Korean patients with HCC, including 159 Hepatitis-B-related cases, 16 Hepatitis-C-related cases, and 114 viral serology-negative cases, who underwent surgery at the Samsung Medical Center in Korea from 2009 to 2014 were enrolled in this study. The presence of AAV2 in fresh-frozen tumor tissues was investigated by DNA PCR and Sanger sequencing. The clinical and pathological characteristics of AAV2-associated HCC in these patients were compared with previous findings in French patients. RESULTS: The AAV2 detection rate in Korean patients (2/289) was very low compared with that in French patients (11/193). Similar to the French patients, the Korean patients with AAV2-related HCC showed no signs of liver cirrhosis. The Korean patients were younger than the French patients with the same AAV2-associated HCC; the ages at diagnosis of the two Korean patients were 47 and 39 yr, while the median age of the 11 French patients was 55 yr (range 43-90 yr). CONCLUSIONS: AAV2-associated HCC was very rare in Korean patients with HCC. Despite a limited number of cases, this study is the first to report the clinical characteristics of Korean patients with AAV2-associated HCC. These findings suggest epidemiologic differences in viral hepatocarcinogenesis between Korean and European patients.

Is the Incidence Rate of Hip Fractures still Increasing in Korea?: An Epidemiologic Study Based on National Health Insurance Database / 대한정형외과학회잡지

PURPOSE: A retrospective study was conducted to examine the current trend in incidence rates of hip fractures among patients aged 50 years and older in Korea. MATERIALS AND METHODS: A retrospective study was conducted using data on the population, collected by Statistics Korea within the different gender and age groups in total population of Korea from 2007 to 2012. The International Classification of Diseases-10 classification method from the Health Insurance Review and Assessment Service was used to investigate the number of patients with hip fractures, and determine the crude incidence rate (CR) and the age-adjusted incidence rate (AR) for comparison. RESULTS: The CR of hip fractures for patients aged 50 years and older was 178 per 100,000 for men and 350 per 100,000 for women in 2007. In 2012, the CR was 194 per 100,000 for men, and 418 per 100,000 for women. The AR was 197 per 100,000 for men and 281 per 100,000 for women in 2007. In 2012, the AR was 206 per 100,000 for men, and 310 per 100,000 for women. During the observation period, the AR and the CR of hip fractures showed a statistically significant increase. However, the increasing trend has been slowing since its peak in 2010. Comparison of the AR of men and women, showed statistical significance only for women. CONCLUSION: In Korea, the incidence of hip fractures increased significantly from 2007 to 2012. The AR showed statistical significance only for women and the increasing trend is slowing down from 2010.

A Novel Method to Measure Superior Migration of the Humeral Head: Step-off of the C-line

BACKGROUND: Superior migration of humeral head has been conventionally determined by measuring the acromiohumeral distance (AHD), We sought to devise a novel measurement system more reliably and accurately than AHD. We described a structural landmark called 'C-line'. In this study, we investigated the clinical usefulness of 'step-off of the C-line (SOC)' compared to that of AHD. METHODS: The C-line formed from the medial margin of the proximal humeral head continuing up to the inferior margin of the articular glenoid and then to the lateral border of the scapula. The superior migration of the humeral head triggered by a rotator cuff tear introduces a discontinuity in this C-line. We measured the distance of this discontinuity. We enrolled 144 patients who underwent a rotator cuff repair. We selected 58 controls who didn't have any cuff lesions apparent on magnetic resonance imaging. Using radiographs derived from standardized true anteroposterior views of the shoulder, we measured the SOC and the AHD. We used t-tests for statistical analyses. RESULTS: A rotator cuff tear was associated with an increase in SOC and a decrease in AHD. In control group, the mean SOC was 1.29 ± 1.71 mm and AHD was 9.71 ± 2.65 mm. In cuff tear group, the mean SOC was 3.15 ± 3.41 mm and AHD was 8.28 ± 1.76 mm. The mean SOCs of the patient group in relation to the mean SOC of the control group according to tear size, the SOCs of medium tear and lager groups showed statistically significant increase (p<0.05). CONCLUSIONS: The SOC may be a similarly effective to diagnose cuff tears of medium size and larger compared with AHD.

Arthroscopic Treatment for Septic Arthritis of the Shoulders in Neonates: A Case Report

Septic arthritis in neonates is a rare condition. A failure to make an early diagnosis of septic arthritis in neonates may leave a permanent disability as a result of a delayed treatment. Thus, septic arthritis, requires a prompt diagnosis and a timely treatment especially in this subset of patients. In this case report, we describe our treatment protocol for septic arthritis and concurrent osteomyelitis in the right shoulder of a 28-day-old newborn. Using 2.4 mm wrist arthroscopy, we performed an arthroscopic irrigation and drainage, to remove intra-articular debris and inflammatory tissue, and multiple drilling. We report a satisfactory clinical outcome without any postoperative complications or side effects.

Biomechanical Test for Repair Technique of Full-thickness Rotator Cuff Tear

The arthroscopic rotator cuff repair is now considered a mainstream technique with highly satisfactory clinical results. However, concerns remain regarding healing failures for large and massive tears and high revision rate. In recent decades, various repair strategies and construct configurations have been developed for rotator cuff repair with the understanding that many factors contribute to the structural integrity of the repaired construct. The focus of biomechanical test in arthroscopic repair has been on increasing fixation strength and restoration of the footprint contact characteristics to provide early rehabilitation and improve healing. These include repaired rotator cuff tendon-footprint motion, increased tendon-footprint contact area and pressure, and tissue quality of tendon and bone. Recent studies have shown that a transosseous tunnel technique provides improved contact area and pressure between rotator cuff tendon and insertion footprint, and the technique of using double rows of suture anchors to recreate the native footprint attachment has been recently described. The transosseous equivalent suture bridge technique has the highest contact pressure and fixation force. In this review, the biomechanical tests about repair techniques of rotator cuff tear will be reviewed and discussed.

A Novel Method to Measure Superior Migration of the Humeral Head: Step-off of the C-line

BACKGROUND: Superior migration of humeral head has been conventionally determined by measuring the acromiohumeral distance (AHD), We sought to devise a novel measurement system more reliably and accurately than AHD. We described a structural landmark called 'C-line'. In this study, we investigated the clinical usefulness of 'step-off of the C-line (SOC)' compared to that of AHD. METHODS: The C-line formed from the medial margin of the proximal humeral head continuing up to the inferior margin of the articular glenoid and then to the lateral border of the scapula. The superior migration of the humeral head triggered by a rotator cuff tear introduces a discontinuity in this C-line. We measured the distance of this discontinuity. We enrolled 144 patients who underwent a rotator cuff repair. We selected 58 controls who didn't have any cuff lesions apparent on magnetic resonance imaging. Using radiographs derived from standardized true anteroposterior views of the shoulder, we measured the SOC and the AHD. We used t-tests for statistical analyses. RESULTS: A rotator cuff tear was associated with an increase in SOC and a decrease in AHD. In control group, the mean SOC was 1.29 ± 1.71 mm and AHD was 9.71 ± 2.65 mm. In cuff tear group, the mean SOC was 3.15 ± 3.41 mm and AHD was 8.28 ± 1.76 mm. The mean SOCs of the patient group in relation to the mean SOC of the control group according to tear size, the SOCs of medium tear and lager groups showed statistically significant increase (p<0.05). CONCLUSIONS: The SOC may be a similarly effective to diagnose cuff tears of medium size and larger compared with AHD.

Arthroscopic Treatment for Septic Arthritis of the Shoulders in Neonates: A Case Report

Septic arthritis in neonates is a rare condition. A failure to make an early diagnosis of septic arthritis in neonates may leave a permanent disability as a result of a delayed treatment. Thus, septic arthritis, requires a prompt diagnosis and a timely treatment especially in this subset of patients. In this case report, we describe our treatment protocol for septic arthritis and concurrent osteomyelitis in the right shoulder of a 28-day-old newborn. Using 2.4 mm wrist arthroscopy, we performed an arthroscopic irrigation and drainage, to remove intra-articular debris and inflammatory tissue, and multiple drilling. We report a satisfactory clinical outcome without any postoperative complications or side effects.

A Population-Based Genomic Study of Inherited Metabolic Diseases Detected Through Newborn Screening

BACKGROUND: A newborn screening (NBS) program has been utilized to detect asymptomatic newborns with inherited metabolic diseases (IMDs). There have been some bottlenecks such as false-positives and imprecision in the current NBS tests. To overcome these issues, we developed a multigene panel for IMD testing and investigated the utility of our integrated screening model in a routine NBS environment. We also evaluated the genetic epidemiologic characteristics of IMDs in a Korean population. METHODS: In total, 269 dried blood spots with positive results from current NBS tests were collected from 120,700 consecutive newborns. We screened 97 genes related to NBS in Korea and detected IMDs, using an integrated screening model based on biochemical tests and next-generation sequencing (NGS) called NewbornSeq. Haplotype analysis was conducted to detect founder effects. RESULTS: The overall positive rate of IMDs was 20%. We identified 10 additional newborns with preventable IMDs that would not have been detected prior to the implementation of our NGS-based platform NewbornSeq. The incidence of IMDs was approximately 1 in 2,235 births. Haplotype analysis demonstrated founder effects in p.Y138X in DUOXA2, p.R885Q in DUOX2, p.Y439C in PCCB, p.R285Pfs*2 in SLC25A13, and p.R224Q in GALT. CONCLUSIONS: Through a population-based study in the NBS environment, we highlight the screening and epidemiological implications of NGS. The integrated screening model will effectively contribute to public health by enabling faster and more accurate IMD detection through NBS. This study suggested founder mutations as an explanation for recurrent IMD-causing mutations in the Korean population.

Biomechanical Test for Repair Technique of Full-thickness Rotator Cuff Tear

The arthroscopic rotator cuff repair is now considered a mainstream technique with highly satisfactory clinical results. However, concerns remain regarding healing failures for large and massive tears and high revision rate. In recent decades, various repair strategies and construct configurations have been developed for rotator cuff repair with the understanding that many factors contribute to the structural integrity of the repaired construct. The focus of biomechanical test in arthroscopic repair has been on increasing fixation strength and restoration of the footprint contact characteristics to provide early rehabilitation and improve healing. These include repaired rotator cuff tendon-footprint motion, increased tendon-footprint contact area and pressure, and tissue quality of tendon and bone. Recent studies have shown that a transosseous tunnel technique provides improved contact area and pressure between rotator cuff tendon and insertion footprint, and the technique of using double rows of suture anchors to recreate the native footprint attachment has been recently described. The transosseous equivalent suture bridge technique has the highest contact pressure and fixation force. In this review, the biomechanical tests about repair techniques of rotator cuff tear will be reviewed and discussed.

DUOX2 Mutations Are Frequently Associated With Congenital Hypothyroidism in the Korean Population

BACKGROUND: Most cases with congenital hypothyroidism (CH) are usually sporadic, while about 20% of the cases are caused by genetic defects. Little information is available regarding the mutation incidence and genetic heterogeneity of CH in Koreans. We aimed to determine the mutation incidence of CH in newborn screenings (NBS) and to evaluate the frequency and spectrum of mutations underlying CH. METHODS: A total of 112 newborns with thyroid dysfunction were enrolled from 256,624 consecutive NBS. Furthermore, 58 outpatients with primary CH were added from an endocrine clinic. All coding exons of TSHR, PAX8, TPO, DUOX2, DUOXA2, and SCL5A5 were sequenced. RESULTS: The mutation incidence of CH was estimated to be 1 in 6,580 newborns. A total of 36 different mutations were identified in 53 cases. The overall mutation positive rate was 31%. The DUOX2 mutations were the most prevalent in both newborns and outpatients. Seven different recurrent mutations [p.G488R (n=13), p.A649E (n=3), p.R885Q (n=3), p.I1080T (n=2), and p.A1206T (n=2) in DUOX2; p.Y138X (n=9) in DUOXA2; and p.R450H (n=5) in TSHR) were identified as the mutations underlying CH. CONCLUSIONS: The mutation incidence of CH was considerably higher than expected in the Korean newborn population. This study revealed seven different recurrent mutations underlying CH. We conclude that DUOX2 mutations are a frequent cause of CH in the Korean population.