Richard Skaba

RET mutation Tyr791Phe the genetic cause of different diseases derived from neural crest

Activating germline RET mutations are presented in patients with familial medullary thyroid carcinoma (FMTC) and multiple endocrine neoplasia (MEN) types 2A and 2B, whereas inactivating germline mutations in patients with Hirschsprung’s disease (HSCR). The aim of this study was to evaluate genotype–phenotype correlations of the frequently discussed Tyr791Phe mutation in exon 13 of the RET proto-oncogene. Screening of three groups of patients was performed (276 families with medullary thyroid carcinoma (MTC), 122 families with HSCR, and 29 patients with pheochromocytoma). We found this mutation in 3 families with apparently sporadic MTC, 3 families with FMTC/MEN2, 1 patient with pheochromocytoma, and 3 families with HSCR. All gene mutation carriers have a silent polymorphism Leu769Leu in exon 13. In three families second germline mutations were detected: Cys620Phe (exon 10) in MEN2A family, Met918Thr (exon 16) in MEN2B family, and Ser649Leu (exon 11) in HSCR patient. Detection of the Tyr791Phe mutation in MEN2/MTC and also in HSCR families leads to the question whether this mutation has a dual character (gain-of-function as well as loss-of-function). A rare case of malignant pheochromocytoma in a patient with the Tyr791Phe mutation is presented. This study shows various clinical characteristics of the frequently discussed Tyr791Phe mutation.

The diagnostic value of MRI fistulogram and MRI distal colostogram in patients with anorectal malformations.

Contrast fistulogram (FG) and distal pressure colostogram (DPCG) are standard diagnostic methods for the assessment of anorectal malformations. Pelvic magnetic resonance imaging (MRI) earned a place among essential diagnostic methods in preoperative investigations after the Currarino syndrome and a high incidence of associated spinal dysraphism were described. The aim of our study was to evaluate the possibility of substituting FG and DPCG by a modified pelvic MRI, e.g. MRI fistulogram (MRI-FG) and MRI colostogram (MRI-DPCG). The prospective study involved 29 patients with anorectal malformations who underwent a modified pelvic MRI. The length and course of fistulas and rectum, and the presence of sacral anomalies were studied on MRI images and compared with images obtained by radiologic examinations. Modified MRI brought identical results as contrast studies in 25 patients when related to the fistula and rectum length and course. MRI was more accurate for the detection of sacral anomalies. MRI-FG was the only imaging method used in the four most recent patients. The results support the assumption that conventional contrast examinations for the assessment of anorectal malformations can be replaced by MRI, thus reducing the radiation dose.

Long-term outcomes after elective ileocecal resection in children with active localized Crohn's disease--a multicenter European study.

PURPOSE The aim of this study was to investigate the therapeutic role of an elective ileocecal resection in children with active localized Crohns disease. METHODS This was a retrospective multicenter study which included five European referral centers which included all children with Crohns disease who underwent ileocecal surgery from 2000 to 2011 and had a minimum of 12 months follow-up. RESULTS Altogether 68 patients fulfilled inclusion criteria. Median age at diagnosis was 13.7 years (6.6-17.9 years) and at surgery 15.2 years (8.6-18.5 years). Median duration of postoperative clinical remission was 20 months (3-95 months). Overall 54 patients (79.4%) were in remission one year after surgery and 38 (55.9%) during the total postsurgical follow up (median 30 months; range 12-95 months). Z score height for age significantly improved postoperatively in children who were at the time of surgery younger than 16 years of age (mean difference 0.232 SD; p=0.029). Cox proportional hazard regression model failed to indicate risk factors associated with postsurgical relapse. CONCLUSION Elective ileocecal resection is a valid treatment option which should be considered in a subset of pediatric patients with localized Crohns disease with the aim of achieving clinical remission and to improve growth.

Hirschsprung's disease and medullary thyroid carcinoma: 15-year experience with molecular genetic screening of the RET proto-oncogene.

PurposeInactivating germline mutations in the RET proto-oncogene are the major genetic cause of Hirschsprung’s disease (HD). In some cases, HD can be associated with medullary thyroid carcinoma (MTC) that is commonly caused by activating RET mutations.MethodsThe retrospective and prospective genetic analyses of 157 patients with HD operated on between December 1979 and June 2011 were carried out. DNA was isolated from peripheral leukocytes. HD patients and family members were tested for RET mutations by direct sequencing and single-strand conformation polymorphism methods.ResultsRET mutations were detected in 16 patients (10%). Association with MTC was found in two families, other eight families had a mutation with potentially high risk of MTC development and four novel mutations were detected. Total colonic aganglionosis was noted to have a high mutation detection rate (40%). Three patients underwent total thyroidectomy (two had clinical manifestation of MTC, one C-cell hyperplasia).ConclusionResults show the benefit of systematic RET mutation screening in HD patients in order to identify the risk of MTC in the preclinical stage of the disease. All patients should be tested for RET mutations at least in exon 10, and now additionally in exon 11 and 13, as well.

RET Variants and Haplotype Analysis in a Cohort of Czech Patients with Hirschsprung Disease

Hirschsprung disease (HSCR) is a congenital aganglionosis of myenteric and submucosal plexuses in variable length of the intestine. This study investigated the influence and a possible modifying function of RET proto-oncogenes single nucleotide polymorphisms (SNPs) and haplotypes in the development and phenotype of the disease in Czech patients. Genotyping of 14 SNPs was performed using TaqMan Genotyping Assays and direct sequencing. The frequencies of SNPs and generated haplotypes were statistically evaluated using chi-square test and the association with the risk of HSCR was estimated by odds ratio. SNP analysis revealed significant differences in frequencies of 11 polymorphic RET variants between 162 HSCR patients and 205 unaffected controls. Particularly variant alleles of rs1864410, rs2435357, rs2506004 (intron 1), rs1800858 (exon 2), rs1800861 (exon 13), and rs2565200 (intron 19) were strongly associated with increased risk of HSCR (p<0.00000) and were over-represented in males vs. females. Conversely, variant alleles of rs1800860, rs1799939 and rs1800863 (exons 7, 11, 15) had a protective role. The haploblock comprising variants in intron 1 and exon 2 was constructed. It represented a high risk of HSCR, however, the influence of other variants was also found after pruning from effect of this haploblock. Clustering patients according to genotype status in haploblock revealed a strong co-segregation with several SNPs and pointed out the differences between long and short form of HSCR. This study involved a large number of SNPs along the entire RET proto-oncogene with demonstration of their risk/protective role also in haplotype and diplotype analysis in the Czech population. The influence of some variant alleles on the aggressiveness of the disease and their role in gender manifestation differences was found. These data contribute to worldwide knowledge of the genetics of HSCR.

Influence of anesthesia on the results of intraoperative diagnostic electromyostimulation in patients with anorectal malformation

BACKGROUND AND PURPOSE Stimulation electromyography (sEMG) is useful in identifying the sphincter muscle (M) in patients with anorectal malformations (ARMs). This study evaluates the effect of anesthetic agents and M relaxants on sEMG findings. MATERIALS AND METHODS Seventeen infants (10 boys and 7 girls) with a mean age of 6.3 months and mean body weight of 6.7 kg were included in a prospective randomized study. Anesthesia was induced by sevoflurane and opioids, and an epidural catheter was inserted caudally. Stimulation electromyography of levator ani M using 14 mA current was used, and latency and amplitude of the evoked compound M action potential (CMAP) were recorded. Patients were randomized into 2 groups. Group A received a local anesthetic epidurally, and sEMG was performed. Administration of the M relaxant and measurement of M response followed. In group B drug administration, sEMG and response measurement were performed after administration of M relaxant. RESULTS Baseline CMAP was recorded in all patients. Average latency was 4.1 milliseconds, and average amplitude was 0.43 mV. In group A, the average latency was 4.0 milliseconds, and average amplitude was 0.65 mV. After administration of the M relaxant, the CMAP disappeared. In group B, no CMAP was observed immediately after administration of the M relaxant. CONCLUSION Administration of the inhalational anesthetic, opioids, and local anesthetic did not influence the M response of M fibers in the levator ani M on sEMG and enables its localization during ARM reconstruction. Nondepolarizing M relaxation completely abolished the response. If M relaxant is necessary, cisatracurium is used. The most suitable method of anesthesia for ARM surgery appears to be inhalational anesthesia supplemented by opioids and epidural analgesia.