Hirschsprung disease (HSCR) is a congenital developmental defect of the enteric nervous system known to be associated with the RET-protooncogene and other candidates. Recently, a genome-wide association study has added NRG1, a regulator of the development of the enteric ganglia precursors, as a new candidate gene. The aim of this study is to validate the association of the RET-protooncogene and the NRG1 in HSCR in Thai patients. The study used TaqMan single-nucleotide polymorphism (SNP) genotyping and PCR-restriction fragment length polymorphism for genotyping of 10 SNPs within the RET-protooncogene and four SNPs within the NRG1, in 68 Thai sporadic HSCR cases and 120 ethnic-matched controls. On univariate disease association analysis, 9 of 10 RET-protooncogene SNPs and all four NRG1 SNPs showed an association with HSCR. The rs2435357 (RET-protooncogene) and rs2439305 (NRG1) showed the strongest associations with the disease at P-values of 8.17E-09 (odds ratio (OR)¼6.43, 95% confidence intervals (CI)¼3.33-12.40) and 6.94E-03 (OR¼3.28, 95% CI¼1.28-8.38), respectively. The RET-protooncogene rs2435357 (TT genotype) in combination with the NRG1 rs2439305 (GG genotype) was strongly associated with an increased risk of HSCR with a P-value of 1.99E-04 (OR¼20.34, 95% CI; 2.54-162.78) when compared with a single SNP of the RET-protooncogene or NRG1. Genetic variation of the RET-protooncogene and NRG1 is involved in the risk of HSCR development in the Thai population. Moreover, the study also detected a combined effect of SNPs by SNP-SNP interaction, which may help in predicting HSCR risk.

Surgery plays an important role in the management of snakebite patients, especially for those with cobra bite with tissue necrosis.

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Constipation is a common problem after reconstructive surgery for anorectal malformations. The underlying pathophysiology of the constipation in these patients is unclear. The objective of this study was to compare manometric disturbance in infants with and without post-anoplasty constipation. Anorectal manometry studies were performed within 12 months of anoplasty, as a part of the follow-up protocol, in 24 infants aged less than 3 years who had anorectal malformations. The manometric profiles studied were mean resting anal pressure (ArP), mean resting rectal pressure (RrP), mean resting rectoanal pressure gradient (RRPG), peak squeeze pressure (PSP), and the presence of the rectoanal inhibitory reflex (RAIR). Eight of 24 infants (33%) experienced constipation during the examination period. There was no difference in pressure profiles between low and non-low anomalies. In the non-constipation group, RrP was 5.1 mmHg, ArP was 21.0 mmHg, RRPG was 16.0 mmHg, and PSP was 88.4 mmHg. In the constipation group, RrP was 7.3 mmHg (p = 0.37), ArP was 37.5 mmHg (p = 0.03), RRPG was 3.05 mmHg (p = 0.05), and PSP was 81.7 mmHg (p = 0.77). RAIR was present in 93.75% of cases without constipation and 12.5% of cases with constipation (p < 0.01). One patient who had clinical conversion from constipation to a good result also showed positive conversion of the RAIR. RAIR and anal resting tone play important roles in emptying function. As far as possible, these functions should be preserved during reconstruction.

A case of initial esophageal atresia and tracheoesophageal fistula in a female newborn, later complicated by pneumonia and a second bronchoesophageal fistula, is reported. She was treated surgically by closure of the tracheoesophageal fistula and by end-to-end esophago-esophageal anastomosis. An esophagram at 1 month of age was normal. Three months later she developed severe, persistent right lower lobe pneumonia that required intensive antibiotic therapy and respiratory support. Esophagography was repeated and revealed a second fistula between the right main-stem bronchus and the lower esophagus. The bronchoesophageal fistula was repaired, and a right lower lobectomy was performed. Postoperative recovery was uncomplicated. Histologic examination indicated that the fistula was congenital in origin. To the best of our knowledge, this is the first reported case of a congenital bronchoesophageal fistula coexisting with a tracheoesophageal fistula and esophageal atresia.

Homozygous mutations of EDNRB in human have been reported to result in Waardenburg-Hirschsprung disease (WS4), while mutated heterozygotes manifested isolated Hirschsprung disease in lower penetrance. We investigated a case of WS4 together with all members of her nuclear family for the alteration of the EDNRB gene by using PCR-SSCP and direct sequencing technique. The index patient, who was born to a family with no history of Hirschsprung disease, presented total colonic aganglionosis with small bowel extension, sensorineural hearing loss and generalized cutaneous pigmentary defects. Interestingly, both irides were normally black. The study detected a homozygous missense mutation at codon 196 in exon 2 (Ser196Asn), which has not been reported. Both parents and four in six siblings harbored heterozygous mutation without any clinical manifestation. Our findings were consistent with previous observations that full spectrum of WS4 occurred to the mutate homozygotes. Moreover, the non-penetrance of heterozygotes in our pedigree, which differs from other reports, demonstrates the high pleiotropic effect of EDNRB mutations in human.

Mutation and polymorphism data for Hirschsprung disease (HSCR) varies among ethnic groups. Single nucleotide polymorphisms (SNP) of RET protooncogene (RET) were recently shown to be associated with the disease, and with disease severity, in different populations. In this study, comprehensive analysis of RET, GDNF, EDNRB, ET-3, and SOX-10 genes among sporadic HSCR in Thailand was conducted by standard PCR-SSCP, RFLP, and sequencing methods. Of 41 patients, 30 cases had rectosigmoid disease (RSD) and 11 cases were assigned to the long-segment disease (LSD) group. Four missense mutations of RET, S100M, R231H, T278N, and G533S, were identified in three patients. One novel missense mutation, V111Q, was detected in EDNRB. For ET-3, two novel missense mutations, D166E and C173R, occurred concomitantly in a patient. The incidence of missense mutation was significantly higher in our female HSCR patient than in the male counterpart. Statistical analysis of the SNPs revealed a significant difference between allele distribution of RET L769L in patients in the LSD and RSD groups. The predominant genotype construct of RET A45A/L769L in our HSCR was GG/GG, which is obviously different from results from all previous studies. The GG/GG genotype construct was associated with RSD and with males. The study also detected a variant allele of RET S836S which has never been reported in Asian cohorts.

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