Surasak Sangkhathat

Renal cell carcinoma in a pediatric patient with an inherited mitochondrial mutation

Renal cell carcinoma (RCC) is a rare pediatric renal cancer. Recent molecular genetic studies discovered a tumor-specific mutation involving translocation of a transcription factor TFE3 in a subset of pediatric RCC with distinct histopathology. We reported a case of a 2-year-old boy with RCC associated with TFE3 translocation resulting in a PRCC-TFE3 fusion gene. Interestingly, the case carried a maternally inherited mitochondrial DNA (mtDNA) alteration at the position which is usually found in MELAS (Mitochondrial Encephalopathy, Lactic Acidosis, and Stroke-like Episodes) syndrome (A3243G). Although evidence of somatic alterations in mtDNA existed in various cancers, association between inherited mtDNA mutation and pediatric renal cancer has not been reported. Our case provided the first evidence of a co-occurrence between a germ line mutation in mtDNA and the somatic mutation of pediatric RCC. With this information, we speculated a role of mitochondria mutation in the pathogenesis of this cancer.

Association of genetic polymorphisms in the RET-protooncogene and NRG1 with Hirschsprung disease in Thai patients.

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)=6.43, 95% confidence intervals (CI)=3.33–12.40) and 6.94E-03 (OR=3.28, 95% CI=1.28–8.38), 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 (OR=20.34, 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.

Somatic mutations of K-ras and BRAF in Thai colorectal cancer and their prognostic value.

BACKGROUND The study aimed to determine the incidence of K-ras and BRAF mutations in colorectal cancers (CRCs) in Thai patients and evaluate association with clinicopathological parameters including treatment outcomes in terms of event free survival (EFS). MATERIALS AND METHODS Two-hundred colorectal cancer specimens were collected for studies of K-Ras codon 12, 13 and 61, and BRAF codon 600 by polymerase chain reaction and direct nucleotide sequencing. RESULTS The overall incidence of K-Ras mutations in our patients was 23%. K-ras mutation frequencies in CRC stages (AJCC) I, II, III and IV were 6.7%, 16.1%, 23.3% and 26.6%, respectively (p-value>0.05). The three most common mutation forms were G12D, G12V and G13D. K-Ras mutation status was associated with poorer EFS in stage I-III CRCs (p-value 0.03). CONCLUSIONS The study found a lower mutation frequency of K-Ras and BRAF compared to reports involving other ethnic groups. However, K-Ras mutations did have a negative prognostic value in early-stage CRCs.

Mutations and polymorphisms of Hirschsprung disease candidate genes in Thai patients

AbstractMutation and polymorphism data for Hirschsprung disease (HSCR) varies among ethnic groups. Single nucleotide polymorphisms (SNP) of RET proto-oncogene (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.

Novel mutation of Endothelin-B receptor gene in Waardenburg–Hirschsprung disease

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.

Primary synovial sarcoma of the abdominal wall: a case report and literature review

Synovial sarcoma (SS) is the fourth most common type of soft tissue sarcoma, following malignant fibrous histiocytoma, liposarcoma, and rhabdomyosarcoma. It usually occurs in the extremities near the large joints of middle-aged patients. We describe a case of synovial sarcoma of the anterior abdominal wall (SSAW) in an adolescent girl and undertake a review of the literature.

Single Nucleotide Polymorphisms in the Gc Gene for Vitamin D Binding Protein in Common Cancers in Thailand

BACKGROUND This case-control study aimed to determine if there were any associations between the two single nucleotide polymorphisms (SNPs) in Gc, rs7041 (Asp416Glu) and rs4588 (Thr420Lys) and 3 common cancers (breast, lung and colorectal) in Thai patients. MATERIALS AND METHODS Two hundred and eighty two colorectal, 101 breast and 113 lung cancer patients were recruited from one institute during 2011-2013. The controls were age-matched volunteers who had a negative history of index cancers. In addition, vitamin D levels were compared among different genotypes in the 2 SNPs. RESULTS The minor allele frequencies of rs7041 (G) and rs4588 (A) were 0.32 and 0.24, respectively. Under the dominant model, the study found significant associations between minor-allele genotypes of the SNP rs7041 (TG/GG) and lung cancer (odds ratio [OR] 1.78, 95% CI 1.05-3.03). When subgroup analysis was performed according to sex and age at diagnosis, the study found that the minor- allele genotypes of rs7041 (TG/GG) were significantly associated with colorectal cancer in patients whose age at diagnosis was more than 60 years (OR 1.67, 95%CI 1.06-2.61) and the minor-allele genotypes of rs4588 (CA/AA) were significantly associated with colorectal cancer in males aged 60 years or less (OR 2.34, 95%CI 1.25-4.37). When SNP combinations (rs7041-rs4588) were examined, the TT-CA combination had a significant protective association with lung cancer (OR 0.44, 95% CI 0.22-0.85). On evaluation of serum 25(OH)D levels in 205 individuals without cancer (males 144, females 61), the proportion of subjects with low serum vitamin D (< 20 ng/ml) in those harboring CA or AA genotypes of rs4588 (41.7%) was significantly higher than the CC genotype (15.5%, p-value < 0.01). CONCLUSIONS Genetic polymorphisms in Gc were associated with lung and colorectal cancers in Thai patients. Lower serum 25(OH)D in minor variants of rs4588 may explain this association.

Clinical outcomes of gastrointestinal stromal tumor in southern Thailand

AIM To review a single institutional experience in clinical management of gastrointestinal stromal tumors (GIST) and analyze for factors determining treatment outcome. METHODS Clinicopathological data of patients with a diagnosis of GIST who were treated at our institute during November 2004 to September 2009 were retrospectively reviewed. RESULTS Ninety-nine cases were included in the analysis. Primary tumor sites were at the stomach in and small bowel in 44% and 33%, respectively. Thirty-one cases already had metastasis at presentation and the most common metastatic site was the liver. Sixty-four cases (65%) were in the high-risk category. Surgical treatment was performed in 77 cases (78%), 3 of whom received upfront targeted therapy. Complete resection was achieved in 56 cases (73% of operative cases) and of whom 27 developed local recurrence or distant metastasis at a median duration of 2 years. Imatinib was given as a primary therapy in unresectable cases (25 cases) and as an adjuvant in cases with residual tumor (21 cases). Targeted therapy gave partial response in 7 cases (15%), stable disease in 27 cases (57%) and progressive disease in 13 cases (28%). Four-year overall survival was 74% (95% CI: 61%-83%). Univariate survival analysis found that low-risk tumor, gastric site, complete resection and response to imatinib were associated with better survival. CONCLUSION The overall outcomes of GIST can be predicted by risk-categorization. Surgery alone may not be a curative treatment for GIST. Response to targeted therapy is a crucial survival determinant in these patients.

Expression of BMP6 is Associated with its Methylation Status in Colorectal Cancer Tissue but Lacks Prognostic Significance

BACKGROUND The study aimed to evaluate the incidence of CpG island promoter methylation of BMP6, a member of the transforming growth factor beta family, in tissue samples from colorectal cancers (CRC) and look for its association with BMP6 expression and clinicopathological correlation. MATERIALS AND METHODS Methylation specific PCR for the BMP6 promoter region was performed with 85 frozen tissue samples of CRC and 45 of normal colon. Methylation status of MLH1 was also determined by the same method. Expression of BMP6 was evaluated by immunohistochemistry (IHC), using Allreds scoring system. The methylation status was analyzed against clinical and pathological parameters in CRC. RESULTS The study revealed BMP6 hypermethylation in 34 of 85 tumor specimens (40%), and 15 out of 45 normal tissue samples from CRC (33%). The incidence of hypermethylation was inversely correlated with IHC score. Allreds scores of 7 or more were correlated with lower frequency of BMP6 hypermethylation (29% compared to 50% in the remaining, p-value 0.049). However, there was no association between hypermethylation status and any clinicopathological parameters. The methylation status of BMP6 was not correlated with that of MLH1, a key methylation determinant in CRC. On survival analysis, there was no significant difference in progress-free survival (PFS) between the cases with and without hypermethylation (2-year PFS 74% and 76%, respectively). CONCLUSIONS CpG island methylation of BMP6 is found in high frequency in CRC and this epigenetic event is associated with suppressed protein expression in the tumor tissue. However, the marker is not associated with tumor progression of the disease.

Crucial role of rectoanal inhibitory reflex in emptying function after anoplasty in infants with anorectal malformations.

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.