Cutting-edge regenerative therapy for Hirschsprung disease and its allied disorders.

Hirschsprung disease (HSCR) and its associated disorders (AD-HSCR) often result in severe hypoperistalsis caused by enteric neuropathy, mesenchymopathy, and myopathy. Notably, HSCR involving the small intestine, isolated hypoganglionosis, chronic idiopathic intestinal pseudo-obstruction, and megacystis-microcolon-intestinal hypoperistalsis syndrome carry a poor prognosis. Ultimately, small-bowel transplantation (SBTx) is necessary for refractory cases, but it is highly invasive and outcomes are less than optimal, despite advances in surgical techniques and management. Thus, regenerative therapy has come to light as a potential form of treatment involving regeneration of the enteric nervous system, mesenchyme, and smooth muscle in affected areas. We review the cutting-edge regenerative therapeutic approaches for managing HSCR and AD-HSCR, including the use of enteric nervous system progenitor cells, embryonic stem cells, induced pluripotent stem cells, and mesenchymal stem cells as cell sources, the recipient intestine's microenvironment, and transplantation methods. Perspectives on the future of these treatments are also discussed.

Exome sequencing identifies novel genes and variants in patients with Hirschsprung disease.

BACKGROUND: Hirschsprung disease (HSCR) is a complex genetic disease characterized by the absence of ganglion cells in the intestines, leading to a functional obstruction in infants. At least 24 genes have been identified for the pathogenesis of HSCR. They contributed to approximately 72% of HSCR cases. We aimed to elucidate further the genetic basis of HSCR in Indonesia using the whole-exome sequencing (WES) approach. METHODS: WES was performed in 39 sporadic non-syndromic HSCR patients and 16 non-HSCR subjects as controls. Variants presented in controls were excluded, followed by in silico prediction tools and population allele frequency databases to select rare variants. We determined the minor allele frequency (MAF) using gnomAD (MAF <0.1%). RESULTS: We involved 24 (61.5%) males and 15 (38.5%) females. Most patients (62%) had short-segment aganglionosis and underwent the Duhamel procedure (41%). We identified several candidate novel variants in HSCR-related genes, including UBR4, GDNF, and ECE1. Moreover, we also identified some novel candidate genes, including a possible compound heterozygous variant in the MUTYH gene: the first variant, a known protein-truncating variant associated with colorectal cancer (CRC), p.Glu452Ter and the second variant is novel, p.Ala39Val. Moreover, the type of variants was not associated with the aganglionosis type. CONCLUSIONS: We identified several novel genes and variants, including the variant associated with CRC, that might contribute to the pathogenesis of HSCR. No genotype-phenotype associations were noted. Our study further confirms the complex network involved in enteric nervous system development and HSCR pathogenesis. LEVEL OF EVIDENCE: Level III.

The impact of NRG1 expressions and methylation on multifactorial Hirschsprung disease.

BACKGROUND: Hirschsprung disease (HSCR) is a complex genetic disorder characterized by the lack of ganglion cells in the intestines. A current study showed that the NRG1 rare variant frequency in Indonesian patients with HSCR is only 0.9%. Here, we investigated the impact of NRG1 expressions and methylation patterns on the pathogenesis of HSCR. METHODS: This cross-sectional study determined NRG1 type I (HRGα, HRGß1, HRGß2, HRGß3, HRGγ, and NDF43 isoforms), type II and type III expressions in both ganglionic and aganglionic colons of 20 patients with HSCR and 10 control colons by real-time polymerase chain reaction (qPCR). For methylation studies, we treated the extracted gDNA from 16 HSCR patients' and 17 control colons with sodium bisulfate and analyzed the methylation pattern of NRG1 exon 1 with methylation-specific PCR. The samples were collected and analyzed at our institution from December 2018 to December 2020. RESULTS: NRG1 types I, II and III expressions were upregulated (17.2-, 3.2-, and 7.2-fold, respectively) in the ganglionic colons compared with control colons (type I: 13.32 ± 1.65 vs. 17.42 ± 1.51, p < 0.01; type II: 13.73 ± 2.02 vs. 16.29 ± 2.19, p < 0.01; type III: 13.47 ± 3.01 vs. 16.32 ± 2.58, p = 0.03; respectively); while only type I (7.7-fold) and HRGß1/HRGß2 (3.3-fold) isoforms were significantly upregulated in the aganglionic colons compared to the controls (type I: 14.47 ± 1.66 vs. 17.42 ± 1.51, p < 0.01; HRGß1/HRGß2: 13.62 ± 3.42 vs 14.75 ± 1.26, p = 0.01). Moreover, the frequency of partially methylated NRG1 was higher in the ganglionic (81%) and aganglionic (75%) colons than in the controls (59%). CONCLUSIONS: Our study provides further insights into the aberrant NRG1 expression in the colons of patients with HSCR, both ganglionic and aganglionic bowel, which might contribute to the development of HSCR, particularly in Indonesia. Furthermore, these aberrant NRG1 expressions might be associated with its methylation pattern.

Is There Any Mosaicism in REarranged During Transfection Variant in Hirschsprung Disease's Patients?

Background: Hirschsprung disease (HSCR) is a heterogeneous genetic disease characterized by the absence of ganglion cells in the intestinal tract. The REarranged during Transfection (RET) is the most responsible gene for its pathogenesis. RET's somatic mosaicisms have been reported for HSCR; however, they are still under-recognized. Therefore, we determined the frequency of somatic mutation of RET rs2435357 in HSCR patients at our institution. Methods: We performed RET rs2435357 genotyping from 73 HSCR formalin-fixed and paraffin-embedded (FFPE) rectal and 60 non-HSCR controls using the PCR-RFLP method. Subsequently, we compared those frequencies of genotypes for RET rs2435357 with our previous genotyping data from 93 HSCR blood specimens. Results: The frequencies of genotypes for RET rs2435357 in HSCR paraffin-embedded rectal were CC 0, CT 11 (15%), and TT 62 (85%), whereas their frequencies in HSCR blood samples were CC 4 (4.3%), CT 22 (23.7%), and TT 67 (72%). Those frequencies differences almost reached a significant level (p = 0.06). Moreover, the frequency of RET rs2435357 risk allele (T) was significantly higher in HSCR patients (135/146, 92.5%) than controls (46/120, 38.3%) (p = 3.4 × 10-22), with an odds ratio of 19.74 (95% confidence interval = 9.65-40.41). Conclusion: Our study suggests somatic mosaicism in HSCR patients. These findings further imply the complexity of the pathogenesis of HSCR. Moreover, our study confirms the RET rs2435357 as a significant genetic risk factor for HSCR patients.

Molecular epidemiology of SARS-CoV-2 isolated from COVID-19 family clusters.

BACKGROUND: Transmission within families and multiple spike protein mutations have been associated with the rapid transmission of SARS-CoV-2. We aimed to: (1) describe full genome characterization of SARS-CoV-2 and correlate the sequences with epidemiological data within family clusters, and (2) conduct phylogenetic analysis of all samples from Yogyakarta and Central Java, Indonesia and other countries. METHODS: The study involved 17 patients with COVID-19, including two family clusters. We determined the full-genome sequences of SARS-CoV-2 using the Illumina MiSeq next-generation sequencer. Phylogenetic analysis was performed using a dataset of 142 full-genomes of SARS-CoV-2 from different regions. RESULTS: Ninety-four SNPs were detected throughout the open reading frame (ORF) of SARS-CoV-2 samples with 58% (54/94) of the nucleic acid changes resulting in amino acid mutations. About 94% (16/17) of the virus samples showed D614G on spike protein and 56% of these (9/16) showed other various amino acid mutations on this protein, including L5F, V83L, V213A, W258R, Q677H, and N811I. The virus samples from family cluster-1 (n = 3) belong to the same clade GH, in which two were collected from deceased patients, and the other from the survived patient. All samples from this family cluster revealed a combination of spike protein mutations of D614G and V213A. Virus samples from family cluster-2 (n = 3) also belonged to the clade GH and showed other spike protein mutations of L5F alongside the D614G mutation. CONCLUSIONS: Our study is the first comprehensive report associating the full-genome sequences of SARS-CoV-2 with the epidemiological data within family clusters. Phylogenetic analysis revealed that the three viruses from family cluster-1 formed a monophyletic group, whereas viruses from family cluster-2 formed a polyphyletic group indicating there is the possibility of different sources of infection. This study highlights how the same spike protein mutations among members of the same family might show different disease outcomes.

The COVID-19 pandemic impact on pediatric surgery residency programs.

BACKGROUND: The residency program as a part of the clinical services itself has been influenced by the COVID-19 outbreak. Several reports have been published regarding the impact of COVID-19 on the residency programs; however, all studies were performed in developed countries or did not comprehensively analyze what residents think about the COVID-19 impact on their residency program. We investigated the impact of the COVID-19 pandemic on the pediatric surgery residency program in our institution as an important part of hospital medical services. METHODS: We developed and distributed a questionnaire to pediatric surgery residents in our institution who were registered from January 2015-July 2020. The questionnaire was consisting of 24 questions: a) the perspectives of residents about COVID-19 infection during their residency program; b) the learning process; c) academic evaluations; and d) residents' suggestions to improve the quality of their residency program during the outbreak. RESULTS: Most (82.6%) pediatric surgery residents agreed that elective surgeries should be postponed during the pandemic. Before the outbreak, almost all (82.6%) residents used textbooks and journals as their primary sources of learning, while during the outbreak, 69.5% of residents shifted to use online lectures either from the school or Association of Pediatric Surgeons. Interestingly, 91.3% of participants agreed that they had more time to complete their academic assignments during the pandemic. CONCLUSIONS: The pandemic has had a significant impact on the development of pediatric surgery residency programs. Moreover, the responses to the questionnaire are affected by the seniority and sex of the residents. A comprehensive approach is needed to maintain the high standard of competence of pediatric surgery without compromising our safety from the COVID-19 infection risk.

Effect of semaphorin 3C gene variants in multifactorial Hirschsprung disease.

OBJECTIVE: Cluster genes, specifically the class 3 semaphorins (SEMA3) including SEMA3C, have been associated with the development of Hirschsprung disease (HSCR) in Caucasian populations. We aimed to screen for rare and common variants in SEMA3C in Indonesian patients with HSCR. METHODS: In this prospective clinical study, we analyzed SEMA3C gene variants in 55 patients with HSCR through DNA sequencing and bioinformatics analyses. RESULTS: Two variants in SEMA3C were found: p.Val337Met (rs1527482) and p.Val579 = (rs2272351). The rare variant rs1527482 (A) was significantly overrepresented in our HSCR patients (9.1%) compared with South Asian controls in the 1000 Genomes (4.7%) and Exome Aggregation Consortium (ExAC; 3.5%) databases. Our analysis using bioinformatics tools predicted this variant to be evolutionarily conserved and damaging to SEMA3C protein function. Although the frequency of the other variant, rs2272351 (G), also differed significantly in Indonesian patients with HSCR (27.3%) from that in South Asian controls in 1000 Genomes (6.2%) and ExAC (4.6%), it is a synonymous variant and not likely to affect protein function. CONCLUSIONS: This is the first comprehensive report of SEMA3C screening in patients of Asian ancestry with HSCR and identifies rs1527482 as a possible disease risk allele in this population.

Aberrant Expressions and Variant Screening of SEMA3D in Indonesian Hirschsprung Patients.

Background: The semaphorin 3D (SEMA3D) gene has been implicated in the pathogenesis of Hirschsprung disease (HSCR), a complex genetic disorder characterized by the loss of ganglion cells in varying lengths of gastrointestinal tract. We wished to investigate the role of SEMA3D variants, both rare and common variants, as well as its mRNA expression in Indonesian HSCR patients. Methods: Sanger sequencing was performed in 54 HSCR patients to find a pathogenic variant in SEMA3D. Next, we determined SEMA3D expression in 18 HSCR patients and 13 anorectal malformation colons as controls by quantitative real-time polymerase chain reaction (qPCR). Results: No rare variant was found in the SEMA3D gene, except one common variant in exon 17, p.Lys701Gln (rs7800072). The risk allele (C) frequency at rs7800072 among HSCR patients (23%) was similar to those reported for the 1,000 Genomes (27%) and ExAC (28%) East Asian ancestry controls (p = 0.49 and 0.41, respectively). A significant difference in SEMA3D expression was observed between groups (p = 0.04). Furthermore, qPCR revealed that SEMA3D expression was strongly up-regulated (5.5-fold) in the ganglionic colon of HSCR patients compared to control colon (ΔCT 10.8 ± 2.1 vs. 13.3 ± 3.9; p = 0.025). Conclusions: We report the first study of aberrant SEMA3D expressions in HSCR patients and suggest further understanding into the contribution of aberrant SEMA3D expression in the development of HSCR. In addition, this study is the first comprehensive analysis of SEMA3D variants in the Asian ancestry.

Full-length genome characterization and phylogenetic analysis of SARS-CoV-2 virus strains from Yogyakarta and Central Java, Indonesia.

BACKGROUND: Recently, SARS-CoV-2 virus with the D614G mutation has become a public concern due to rapid dissemination of this variant across many countries. Our study aims were (1) to report full-length genome sequences of SARS-CoV-2 collected from four COVID-19 patients in the Special Region of Yogyakarta and Central Java provinces, Indonesia; (2) to compare the clade distribution of full-length genome sequences from Indonesia (n = 60) from March to September 2020 and (3) to perform phylogenetic analysis of SARS-CoV-2 complete genomes from different countries, including Indonesia. METHODS: Whole genome sequencing (WGS) was performed using next-generation sequencing (NGS) applied in the Illumina MiSeq instrument. Full-length virus genomes were annotated using the reference genome of hCoV-19/Wuhan/Hu-1/2019 (NC_045512.2) and then visualized in UGENE v. 1.30. For phylogenetic analysis, a dataset of 88 available SARS-CoV-2 complete genomes from different countries, including Indonesia, was retrieved from GISAID. RESULTS: All patients were hospitalized with various severities of COVID-19. Phylogenetic analysis revealed that one and three virus samples belong to clade L and GH. These three clade GH virus samples (EPI_ISL_525492, EPI_ISL_516800 and EPI_ISL_516829) were not only located in a cluster with SARS-CoV-2 genomes from Asia but also those from Europe, whereas the clade L virus sample (EPI_ISL_516806) was located amongst SARS-CoV-2 genomes from Asia. Using full-length sequences available in the GISAID EpiCoV Database, 39 of 60 SARS-CoV-2 (65%) from Indonesia harbor the D614G mutation. CONCLUSION: These findings indicate that SARS-CoV-2 with the D614G mutation appears to become the major circulating virus in Indonesia, concurrent with the COVID-19 situation worldwide.

Aberrant UBR4 expressions in Hirschsprung disease patients.

BACKGROUND: Recently, pathogenic alleles within ubiquitin N-recognin domain-containing E3 ligase 4 (UBR4) gene have been shown to be associated with Hirschsprung disease (HSCR). We determined the UBR4 expressions in Indonesian HSCR patients. METHODS: We analyzed the UBR4 expressions in the colons of HSCR patient and anorectal malformation (ARM) patient as control by real-time polymerase chain reaction (qPCR). RESULTS: Thirty-seven patients with non-syndromic HSCR and eighteen controls were involved in this study. qPCR revealed that the UBR4 expression was strongly decreased (0.77-fold) in the ganglionic group of patients with HSCR compared to the control group with ARM (ΔCT 2.43 ± 0.36 vs. 2.05 ± 0.69; p = 0.009), whereas the UBR4 expression was also significantly reduced (0.79-fold) in the aganglionic group of patients with HSCR compared to the control group with ARM (ΔCT 2.39 ± 0.46 vs. 2.05 ± 0.69; p = 0.044). However, the UBR4 expression change was not associated with gender (p = 0.35 and 0.80), nor with degree of aganglionosis both in ganglionic and aganglionic colons (p = 0.72 and 0.73), respectively. CONCLUSION: Our study demonstrates that expression of UBR4 is decreased in both aganglionic and ganglionic colon of HSCR patients.

P21 Ser31Arg and FGFR2 rs2981582 Polymorphisms as Risk Factors for Early Onset of Breast Cancer in Yogyakarta, Indonesia.

OBJECTIVES: Breast cancer tend to be more progressive with poorer prognosis in younger patients than those at an older age. Single Nucleotide Polymorphisms (SNPs) of P53 Pro72Arg, MDM2 SNP309, P21 Ser31Arg, ER SNP594, HER2 Ile655Val, and FGFR2 rs2981582 have drawn attention as genetic factors associated with cancer risk. However, there were contradictory results involving different races and their association is still unknown in Indonesian populations. This study was performed to examine the proportion of these six genes polymorphisms and their associations with age of onset of breast cancer patients in Yogyakarta, Indonesia. METHODS: Biorepository DNA from 199 patients registered at Dr. Sardjito Hospital Yogyakarta from 2006-2013 were tested for polymorphisms using the PCR-RFLP method. Samples were taken from two age groups; early-onset (55 years). Chi-square tests with odds ratio were used for data analysis. RESULTS: The mean age of the early-onset group was 36±4.2 years, while the late-onset group was 62±6.9 years. AA genotype and A allele of P21 and TT genotypes and T allele of FGFR2 were significantly more frequent and were associated with an increased risk of early-onset of breast cancer (95%CI: 2.54 and 1.59; 2.63 and 1.64, respectively). CONCLUSIONS: Our study indicates that the A allele of P21 and the allele T of FGFR2 may be associated with an increased risk of early-onset of breast cancer in Yogyakarta, Indonesia. Further analysis is needed to confirm the findings.

The analysis of DMD gene deletions by multiplex PCR in Indonesian DMD/BMD patients: the era of personalized medicine.

OBJECTIVE: Duchenne/Becker muscular dystrophy (DMD/BMD) is the most common genetic neuromuscular disease in children, resulting from a defect in the DMD gene located on Xp21.2. The new emerging treatment using exon skipping strategy is tailored to specific mutations, thus molecular diagnostics are particularly important. This study aimed to detect the DMD gene deletion in Indonesian DMD/BMD patients and analyze the potential amenability by exon skipping therapy. RESULTS: Thirty-four male patients were enrolled in this study, 23 of them (67.6%) underwent muscle biopsy and showed the absence or partially expressed dystrophin protein in immunohistochemistry staining. All patients had very high serum CK levels (10.529 ± 9.97 IU/L). Multiplex PCR revealed the DMD gene deletions in 15 (44.1%) cases. Seventy-eight percent of deletions were clustered in the hot-spot region of exon 43 to 52. Furthermore, seven (20.5%) patients were potentially amenable to exon skipping treatment. Therefore, multiplex PCR is one feasible method to detect DMD gene deletion in Indonesian DMD/BMD patients that can further determine the potential amenability of exon skipping therapy. In addition, this study is the first report of DMD gene deletion analysis in Indonesia.

microRNA-21 expressions impact on liver fibrosis in biliary atresia patients.

OBJECTIVE: Biliary atresia (BA) is the most common cause of neonatal jaundice, characterized by progressive and rapid liver fibrosis. Recent studies have shown that microRNAs (miRNAs) contribute to the liver fibrogenesis. We investigated the miRNA-21 impact in liver fibrogenesis in Indonesian BA patients. RESULTS: There were 5, 4, and 7 BA patients with type 2A, 2B, and 3, respectively. Quantitative real-time polymerase chain reaction (qPCR) showed that the miRNA-21 expression was significantly increased (18-fold) in BA patients compared to controls (- 4.4 ± 4.0 vs. - 0.2 ± 4.8; p = 0.041). Furthermore, the phosphatase and tensin homolog deleted on chromosome ten (PTEN) expression was significantly down-regulated (3.1-fold) in BA group compared to control group (0.2 ± 1.4 vs. - 1.4 ± 1.7; p = 0.036). The α-smooth muscle actin (α-SMA) expression was not statistically significantly different between groups (13.7 ± 3.8 vs. 15.0 ± 4.8; p = 0.87). Interestingly, the miRNA-21 expression was significantly lower (25-fold) in cirrhosis than non-cirrhosis BA patients (- 0.8 ± 2.2 vs. - 5.3 ± 3.9; p = 0.004). In conclusions, our study provides support for the association between miRNA-21 expression and liver cirrhosis in BA patients. Further study with a larger sample size of patients is important to confirm our results.

Aberrant expressions of miRNA-206 target, FN1, in multifactorial Hirschsprung disease.

BACKGROUND: MicroRNAs (miRNAs) have been associated with the Hirschsprung disease (HSCR) pathogenesis, however, the findings are still inconclusive. We aimed to investigate the effect of miRNA-206 and its targets, fibronectin 1 (FN1), serum deprivation response (SDPR), and paired box 3 (PAX3) expressions on multifactorial HSCR in Indonesia, a genetically distinct group within Asia. METHODS: We determined the miRNA-206, FN1, SDPR and PAX3 expressions in both the ganglionic and aganglionic colon of HSCR patients and control colon by quantitative real-time polymerase chain reaction (qRT-PCR). RESULTS: Twenty-one sporadic HSCR patients and thirteen controls were ascertained in this study. The miRNA-206 expression was up-regulated (2-fold) in the ganglionic colon and down-regulated (0.5-fold) in the aganglionic colon compared to the control group (ΔCT 12.4 ± 3.0 vs. 14.1 ± 3.9 vs. 13.1 ± 2.7), but these differences did not reach significant levels (p = 0.48 and p = 0.46, respectively). Interestingly, the FN1 expression was significantly increased in both the ganglionic (38-fold) and aganglionic colon (18-fold) groups compared to the control group ΔCT 5.7 ± 3.0 vs. 6.8 ± 2.3 vs. 11.0 ± 5.0; p = 0.001 and p = 0.038, respectively). Furthermore, the expressions of SDPR were similar in the ganglionic, aganglionic and control colon groups (ΔCT 2.4 ± 0.6 vs. 2.2 ± 0.4 vs. 2.1 ± 0.6; p = 0.16 and p = 0.39, respectively), while no change was observed in the PAX3 expression between the ganglionic, aganglionic, and control colon groups (ΔCT 3.8 ± 0.8 vs. 4.1 ± 0.8 vs. 3.7 ± 1.1; p = 0.83 and p = 0.44, respectively). CONCLUSION: Our study is the first report of aberrant FN1 expressions in the colon of patients with HSCR and supplies further insights into the contribution of aberrant FN1 expression in the HSCR pathogenesis.

Use of air stacking to improve pulmonary function in Indonesian Duchenne muscular dystrophy patients: bridging the standard of care gap in low middle income country setting.

BACKGROUND: Duchenne Muscular Dystrophy (DMD) is a fatal X-linked recessive neuromuscular disease, characterized by progressive loss of muscle strength. Respiratory failure is the main cause of morbidity and mortality in DMD patients. Respiratory devices have been reported to increase the effectiveness of cough and pulmonary function, thus prolong the survival rate. However, there is scarcity of studies about DMD patients' respiratory profiles and usage of respiratory devices in Indonesia. METHODS: We recruited 8 Indonesian DMD patients in Dr. Sardjito Hospital and UGM Academic Hospital, Yogyakarta. Baseline pulmonary function was measured using spirometry. Peak Cough Flow was measured at baseline, with chest compression, after air stacking with manual ventilation bag, and with the combined techniques. Data recorded was presented as mean ± SD and analysed using ANOVA. RESULTS: Here we show the respiratory profiles from 8 non-ambulatory DMD patients (mean age: 13.25 ± 3.96 years old) confirmed by genetic testing. None of them had access to respiratory devices. Spirometry measurements showed 7 of 8 patients had severe restrictive pulmonary function with mean FEV1/FVC 22.40 ± 10.30% of predictive values (normal ratio > 70%). In addition, all patients showed poor cough performances measured by peak cough flowmeter (160 ± 44.58 L/min (normal value > 270 L/min)) that were improved by air stacking using a manual ventilation bag (167.4 ± 46.72 L/min). Three patients who had nocturnal hypoventilation did not have daytime hypercapnia. Manual ventilation bag or mechanical in-/ex-sufflation was indicated in 75% of patients while nocturnal assisted ventilation was indicated in 50% of patients. Neither daytime assisted ventilation nor tracheostomy was indicated in these patients. CONCLUSION: Use of manual exsufflation in combination with the manual ventilation bag for air stacking to improve cough performance is recommended as the first step of respiratory management in DMD patients. Provision of manual ventilation bag serve as an affordable and effective device for respiratory support in the early stage of respiratory involvement in those non-ambulatory patients with DMD.

NRG1 variant effects in patients with Hirschsprung disease.

BACKGROUND: Hirschsprung disease (HSCR) is a heterogeneous genetic disorder characterized by absence of ganglion cells along the intestines resulting in functional bowel obstruction. Mutations in neuregulin 1 (NRG1) gene have been implicated in some cases of intestinal aganglionosis. This study aims to investigate the contribution of the NRG1 gene to HSCR development in an Indonesian population. METHODS: We analyzed the entire coding region of the NRG1 gene in 54 histopathologically diagnosed HSCR patients. RESULTS: All patients were sporadic non-syndromic HSCR with 53/54 (98%) short-segment and 1/54 (2%) long-segment patients. NRG1 gene analysis identified one rare variant, c.397G > C (p.V133 L), and three common variants, rs7834206, rs3735774, and rs75155858. The p.V133 L variant was predicted to reside within a region of high mammalian conservation, overlapping with the promoter and enhancer histone marks of relevant tissues such as digestive and smooth muscle tissues and potentially altering the AP-4_2, BDP1_disc3, Egr-1_known1, Egr-1_known4, HEN1_2 transcription factor binding motifs. This p.V133 L variant was absent in 92 non-HSCR controls. Furthermore, the rs7834206 polymorphism was associated with HSCR by case-control analysis (p = 0.037). CONCLUSIONS: This study is the first report of a NRG1 rare variant associated with HSCR patients of South-East Asian ancestry and provides further insights into the contribution of NRG1 in the molecular genetic pathogenesis of HSCR.

The impact of down-regulated SK3 expressions on Hirschsprung disease.

BACKGROUND: Some Hirschsprung's disease (HSCR) patients showed persistent bowel symptoms following an appropriately performed pull-through procedure. The mechanism is presumed to be down-regulated small-conductance calcium-activated potassium channel 3 (SK3) expression in the HSCR ganglionic intestines. We aimed to investigate the SK3 expression's impact in HSCR patients after a properly performed pull-through surgery in an Indonesian population, a genetically distinct group within Asia. METHODS: We assessed SK3 gene expression in both the ganglionic and aganglionic colon of HSCR patients and controls colon by quantitative real-time polymerase chain reaction (RT-PCR). RESULTS: We ascertained fourteen sporadic HSCR patients and six anorectal malformation patients as controls. Quantitative RT-PCR showed that the SK3 expression was significantly lower (23-fold) in the ganglionic colon group compared to the control group (9.9 ± 4.6 vs. 5.4 ± 3.4; p = 0.044). The expression of SK3 in the aganglionic colon group was also significantly lower (43-fold) compared to the control group (10.8 ± 4.4 vs. 5.4 ± 3.4; p = 0.015). CONCLUSION: Our study shows that the down-regulated SK3 expression in ganglionic intestines might contribute to the persistent bowel symptoms following a properly performed pull-through surgery in Indonesian HSCR patients. Furthermore, this study is the first report of SK3 expression in a sample population of Asian ancestry.