Yeoun Joo Lee

Genome-wide association study of Crohn's disease in Koreans revealed three new susceptibility loci and common attributes of genetic susceptibility across ethnic populations

Objective Crohns disease (CD) is an intractable inflammatory bowel disease (IBD) of unknown cause. Recent meta-analysis of the genome-wide association studies (GWAS) and Immunochip data identified 163 susceptibility loci to IBD in Caucasians, however there are limited studies in other populations. Methods We performed a GWAS and two validation studies in the Korean population comprising a total of 2311 patients with CD and 2442 controls. Results We confirmed four previously reported loci: TNFSF15, IL23R, the major histocompatibility complex region, and the RNASET2-FGFR1OP-CCR6 region. We identified three new susceptibility loci at genome-wide significance: rs6856616 at 4p14 (OR=1.43, combined p=3.60×10−14), rs11195128 at 10q25 (OR=1.42, combined p=1.55×10−10) and rs11235667 at 11q13 (OR=1.46, combined p=7.15×10−9), implicating ATG16L2 and/or FCHSD2 as novel susceptibility genes for CD. Further analysis of the 11q13 locus revealed a non-synonymous single nucleotide polymorphism (SNP) (R220W/rs11235604) in the evolutionarily conserved region of ATG16L2 with stronger association (OR=1.61, combined p=2.44×10−12) than rs11235667, suggesting ATG16L2 as a novel susceptibility gene for CD and rs11235604 to be a potential causal variant of the association. Two of the three SNPs (rs6856616 (p=0.00024) and rs11195128 (p=5.32×10−5)) showed consistent patterns of association in the International IBD Genetics Consortium dataset. Together, the novel and replicated loci accounted for 5.31% of the total genetic variance for CD risk in Koreans. Conclusions Our study provides new biological insight to CD and supports the complementary value of genetic studies in different populations.

High incidence of PRSS1 and SPINK1 mutations in Korean children with acute recurrent and chronic pancreatitis.

Objectives: We evaluated the frequencies and clinical consequences of mutations in the genes encoding cationic trypsinogen, serine protease 1 (PRSS1), and serine protease inhibitor Kazal type 1 (SPINK1) in children with acute recurrent pancreatitis (ARP) and chronic pancreatitis (CP). Patients and Methods: The study population consisted of 32 children with ARP or CP and 28 healthy controls. We analyzed clinical data and the sequences of the entire coding region and the intron-exon boundaries of the PRSS1 and SPINK1 genes from each patient. Results: Fifteen (46.9%) of the 32 patients had at least 1 PRSS1 or SPINK1 mutation. Four (12.5%) of the 32 patients carried the p.N29I, p.R122H, or p.N29T mutation or a p.G208A variant of the PRSS1 gene in a heterozygote state. Eleven (34.4%) of the 32 patients carried either the IVS3 + 2T>C or p.N34S mutation of the SPINK1 gene. No PRSS1 or SPINK1 mutations were identified in the control group. In particular, mutations were identified in 4 of our patients who experienced pancreas divisum with CP, whereas the remaining 2 patients with pancreas divisum and ARP did not have mutation. Conclusions: The frequencies of the PRSS1 and SPINK1 mutations are relatively high in Korean children with ARP or CP. Mutations in the PRSS1 and SPINK1 genes are highly associated with the development of childhood ARP or CP. Our findings suggest that patients with genetic mutations combined with pancreas divisum tend to develop CP early.

Long-term outcomes of pediatric living donor liver transplantation at a single institution

Oh SH, Kim KM, Kim DY, Lee YJ, Rhee KW, Jang JY, Chang SH, Lee SY, Kim J‐S, Choi BH, Park S‐J, Yoon CH, Ko G‐Y, Sung K‐B, Hwang G‐S, Choi K‐T, Yu E, Song G‐W, Ha T‐Y, Moon D‐B, Ahn C‐S, Kim K‐H, Hwang S, Park K‐M, Lee Y‐J, Lee S‐G. Long‐term outcomes of pediatric living donor liver transplantation at a single institution.
Pediatr Transplantation 2010: 14:870–878.

Identification of KMT2D and KDM6A mutations by exome sequencing in Korean patients with Kabuki syndrome

Kabuki syndrome (KS) (OMIM#147920) is a multiple congenital anomaly/mental retardation syndrome. Recently, pathogenic variants in KMT2D and KDM6A were identified as the causes of KS in 55.8–80.0% of patients. To elucidate further the molecular characteristics of Korean patients with KS, we screened a cohort of patients with clinically defined KS for mutations in KMT2D and KDM6A. Whole-exome sequencing and direct sequencing for validation were performed in 12 patients with a clinical suspicion of KS. KMT2D and KDM6A mutations were identified in 11 (91.7%) patients. No recurrent mutation was observed, and 10 out of the 11 mutations found were novel. KMT2D mutations were detected in 10 patients, including four small deletions or insertions and four nonsense and two missense mutations. One girl had a novel splice-site mutation in KDM6A. Each patient had a unique individual mutation. This is the first report of mutational analysis via exome sequencing in Korean patients with KS. Because the mutation-detection rate was high in this study, rigorous mutation analysis of KMT2D and KDM6A may be an important tool for the early diagnosis and genetic counseling of Korean patients with KS.

Infections after living donor liver transplantation in children.

The aim of this study was to evaluate the infectious complications after living donor liver transplantation (LDLT) in children. We enrolled 95 children (38 boys and 57 girls) who underwent LDLT from 1994 to 2004. The median age was 22 months (range, 6 months to 15 yr). We retrospectively investigated the proven episodes of bacterial, viral, and fungal infection. There occurred 150 infections in 67 (70%) of 95 patients (1.49 infections/patient); 74 in 43 patients were bacterial, 2 in 2 were fungal, and 74 in 42 were viral. The most common sites of bacterial infection were the bloodstream (33%) and abdomen (25%). Most of the bacterial infections occurred within the first month after LDLT. Bacterial and fungal infections did not result in any deaths. The most common causes of viral infection were Epstein-Barr virus in 37 patients and cytomegalovirus in 18. Seven of the 14 deaths after LDLT were associated with viral infection. Our study suggests that infection is one of the important causes of morbidity and mortality after LDLT. Especially careful monitoring and management of viral infections is crucial for improving the outcome of LDLT in children.

NUDT15 variant is the most common variant associated with thiopurine-induced early leukopenia and alopecia in Korean pediatric patients with Crohn's disease.

Purpose Thiopurine-induced leukopenia is a relatively common adverse event related to thiopurine medication in Korean pediatric Crohn’s disease. In addition to the mutations of TPMT gene, the NUDT15 c.415C>T variant was recently identified to have a strong association with thiopurine-induced early leukopenia. We conducted this study to define the incidence of azathioprine (AZA)-related leukopenia and to determine the incidence and characteristics of their genetic variants in Korean pediatric Crohn’s disease patients. Patients and methods Patients diagnosed with pediatric Crohn’s disease who had used AZA for more than 3 months were recruited. The dose and duration of medication and data regarding adverse events including leukopenia were collected. TPMT and NUDT15 gene sequencing was performed for patients who had experienced AZA-induced leukopenia. Results A total of 81 patients had used AZA as a maintenance therapy of Crohn’s disease. The mean dose of AZA was 1.88±0.39 mg/kg/day. Nine patients (11.1%) experienced AZA-induced leukopenia, and eight patients (9.9%) experienced AZA-induced early leukopenia. Among the eight early leukopenia patients, six patients (75.0%) harbored the NUDT15 c.415C>T variant and one patient (12.5%) had the TPMT c.719A>G (TPMT*3C) variant. All the three patients with NUDT15 c.415C>T homozygous variant suffered from alopecia totalis, and two of them experienced severe systemic infection. Three patients with the NUDT15 heterozygous variant are currently treated with AZA at a dose of 0.76 mg/kg/day. Conclusion Mutations of the NUDT15 and TPMT gene accounted for ∼88% of cases with thiopurine-induced early leukopenia. Extensive hair loss was a recognizable early symptom in patients with the homozygous NUDT15 c.415C>T variant. Sequencing of the NUDT15 genes can guide the clinicians before thiopurine medication. An alternative immunosuppressive medication is recommended for patients with homozygous NUDT15 c.415C>T variant. For those with the heterozygous variant, half the usual dose of AZA can achieve efficacy comparable to that for wild-type patients.

Improved outcomes in liver transplantation in children with acute liver failure.

Objective: The aim of our study was to review the experiences of a living donor–dominant transplantation program for children with acute liver failure (ALF). Methods: Data were derived from the retrospective chart review of 50 children with ALF in a major liver center in the Republic of Korea. Results: A total of 50 children with ALF underwent 47 (94%) primary living donor liver transplantations and 3 (6%) cadaveric liver transplantations. The cumulative survival rates of the grafts at 1 and 5 years were 81.9% and 79.2%, respectively. The overall retransplantation rate was 12%. The cumulative survival rates of these patients at 1 and 5 years were all 87.9%. Most incidents of mortality followed the failure of the preceding graft. We observed no mortalities among donors. Based on multivariate analysis, children who had pretransplant thrombocytopenia or had to use the molecular adsorbent recycling system preoperatively were related to the graft loss. Age younger than 2 years and a hyperacute onset (within 7 days) of hepatic encephalopathy were associated with pretransplant thrombocytopenia. Conclusions: Living donor–dominant transplantation program in the present study demonstrates tolerable achievements in terms of clinical outcomes of recipients and donors; however, putative factors, such as pretransplant thrombocytopenia, seem to play unclear roles in a poor prognosis following transplantation.

Diagnostic sensitivity of culture and drug resistance patterns in Korean patients with intestinal tuberculosis.

SETTING It is challenging to differentiate between intestinal tuberculosis (ITB) and Crohns disease in areas where TB is still prevalent. The use of diagnostic tools and verifying the drug resistance patterns of ITB can be helpful for its correct diagnosis. OBJECTIVE To determine the diagnostic sensitivity of a culture assay using colonoscopic biopsy specimens and the drug resistance patterns of Mycobacterium tuberculosis isolated from ITB. DESIGN Data from 400 patients diagnosed with ITB were retrospectively analysed. RESULTS Of the 400 patients, 170 (42.5%) were males; the median age at diagnosis was 40 years. The sensitivity of culture was 44.1% (145/329). Resistance to at least one anti-tuberculosis drug was identified in 13 (17.6%) and multidrug-resistant TB (MDR-TB) was diagnosed in two (2.7%) of the 74 patients for whom drug susceptibility testing was performed. Including M. tuberculosis isolated from respiratory specimens, the proportion of MDR-TB was 4.4% (5/113); previous anti-tuberculosis treatment was an independent risk factor for MDR-TB (26.7% vs. 1.0%, P < 0.01). CONCLUSION Culture of colonoscopic biopsy specimens shows substantial diagnostic sensitivity; the frequency of MDR-TB is higher in previously treated cases than in new cases.

Determinants of recurrence after successful treatment of Mycobacterium avium complex lung disease.

BACKGROUND The long-term treatment outcomes of Mycobacterium avium complex (MAC) lung disease (LD) have not been adequately evaluated. OBJECTIVE We evaluated the determinants of microbiological recurrence after successful treatment for MAC LD. DESIGN The medical records of 295 MAC LD patients treated with combination chemotherapy from 2004 to 2013 were reviewed. The clinical data, microbiological study results and chest computerised tomography findings were collected for each patient. RESULTS Ninety-one patients who maintained negative sputum conversion during treatment and had a minimum 10-month follow-up period after treatment were included. The median duration of follow-up was 25 months. Seventy-one (78.0%) patients remained microbiologically disease-free, while 20 (22.0%) had microbiological recurrence after successful treatment. Age, sex and body mass index were not associated with microbiological recurrence. Longer intervals between initial diagnosis and administration of medication (P = 0.024), increased number of involved lobes (P = 0.033) and failure of sputum conversion within 6 months of initiating treatment (P = 0.017) were significantly associated with microbiological recurrence. CONCLUSION Microbiological recurrence after successful anti-MAC chemotherapy was associated with the time interval between initial diagnosis and administration of medication, number of lobes involved and time to sputum conversion during treatment.

Risk factors for deterioration of nodular bronchiectatic Mycobacterium avium complex lung disease.

UNLABELLED SETTING The long-term natural course of Mycobacterium avium complex (MAC) disease with nodular bronchiectasis, the most common pulmonary non-tuberculous mycobacterial disease, is not well described. OBJECTIVE To identify risk factors for the deterioration of nodular bronchiectatic MAC lung disease over a 5-year follow-up period. DESIGN Clinical and laboratory data of 67 patients with nodular bronchiectatic MAC lung disease were collected. Chest computerised tomographic images were used to count the number of lung segments involved at diagnosis and measure subcutaneous fat thickness during follow-up. RESULTS The 34 patients who showed deterioration had significantly lower body mass index (BMI) (P = 0.004) and % predicted forced vital capacity (P = 0.032), higher numbers of lung segments involved (P < 0.001) and MAC-positive sputum cultures (P = 0.028), and thinner chest subcutaneous fat during follow-up (P < 0.001) than patients without deterioration. In particular, patients with both BMI <21.0 kg/m(2) and more than four lung segments involved had a 240-fold increased risk of deterioration (P < 0.001). CONCLUSION Patients with poor nutritional status and extensive lung involvement tend to experience deterioration of nodular bronchiectatic MAC lung disease.