Hirschsprung's disease: clinical and experimental observations

In vivo detection of Hirschsprung's disease by optical coherence tomography in rats

Hirschsprung's disease (HSCR) is a developmental intestinal obstruction, which is often diagnosed with a repeated biopsy. Optical coherence tomography (OCT) is a noninvasive, real-time imaging modality. This study aims to investigate the feasibility of diagnosis of HSCR, the targeted biopsies of suspicious tissues and the location of operative treatment using OCT. An HSCR Sprague-Dawley (SD) rat model (benzalkonium chloride-treated (BAC-treated)) was used. Colon tissues with BAC-treated and without BAC-treated were imaged using OCT. To establish OCT criteria for identification of HSCR, OCT images were compared with corresponding histology images and muscle layer thickness was measured. Furthermore, attenuation coefficients of OCT signals were calculated to illustrate the differences between tissues with BAC-treated and without BAC-treated. Our results show that OCT images of colon tissues with HSCR are well correlated with histology images. In comparison with a muscle layer without HSCR, the thickness of muscle layer with HSCR is increased significantly. The muscle layer in colon tissues with HSCR for 6 weeks had a higher attenuation coefficient than those without HSCR. However, the attenuation coefficient of those with HSCR for 3 weeks had no obvious change. In conclusion, the study demonstrates for the first time that OCT has the potential for diagnosis, biopsy and location of HSCR in vivo.

Intestinal obstruction in neonatal/pediatric surgery

Intestinal obstruction in the newborn infant and older child may be due to a variety of conditions, including atresia and stenosis, annular pancreas, malrotation, duplication cyst, meconium ileus, meconium plug syndrome and neonatal small left colon syndrome, Hirschsprung's disease, neoplasia, trauma, and other rarer causes. The mode of presentation can be acute or more chronic with systemic upset due to shock. Neonates, more so than older children, with unrecognized intestinal obstruction deteriorate rapidly, show an increase of associated morbidity and mortality and appropriate surgical treatment becomes more hazardous. Early diagnosis depends largely on the prompt detection of obstructive manifestations by the clinician and the subsequent accurate interpretation of radiographic findings and other investigations, leading to definitive treatment, which should always be preceded by appropriate resuscitation/preparation of the infant/child. Management of intestinal obstruction will almost always be surgical, apart from some notable exceptions and all are discussed in more detail. With the advent of pediatric and neonatal intensive care and multidisciplinary care, the morbidity and mortality of cases of intestinal obstruction reported in current series is generally extremely low and mainly determined by the coexistence of other major congenital anomalies (eg, cardiac), delays in diagnosis and treatment or coexisting medical conditions. Newer treatments and future developments may reduce the residual mortality in such cases as ultrashort-bowel syndrome.

The constipated child: how likely is Hirschsprung's disease?

The incidence of Hirschsprung's disease (HD) was determined in children who presented with constipation to a specialist paediatric surgical unit. During a 5-year period, 355 rectal biopsies were performed on 182 neonates, infants and children presenting with chronic constipation or intestinal obstruction: 25 (14%) were diagnosed HD. One hundred and four patients had suction and 78 had full-thickness rectal biopsies. Haematoxylin-eosin (HE) staining and acetylcholinesterase (AChE) histochemistry was used. In 13 cases (8%) of suction and 2 cases (2.5%) of full thickness rectal biopsies, specimens were inadequate to diagnose HD. The mean age of all patients was 2.9 years and that of patients diagnosed with HD was 3.64 months. Nineteen patients with HD were diagnosed in the first month, 5 in 1-12 months and 1 at 4 years of age (Fig. 1). The authors found that along with onset of constipation convincing indications for rectal biopsy to exclude HD were as follows: those infants and children who do not pass meconium within 48 hours, have low intestinal obstruction of unknown cause, severe constipation, chronic abdominal distension and failure to thrive. A diagnostic accuracy of 94% was achieved with AChE histochemistry for suction rectal biopsy. After this review, referring paediatricians were advised that screening of other common organic causes of constipation with the least invasive investigations, including laboratory, dietary and paediatric gastroenterology advice, should be undertaken to avoid unnecessary rectal biopsy to exclude HD and related disorders.

MUC-2 mucin production in Hirschsprung's disease: possible association with enterocolitis development

BACKGROUND/PURPOSE

The etiology of Hirschsprung's-associated enterocolitis (HAEC) is unknown. Previous investigations have suggested that abnormal production of mucins may have an etiologic role. Recently, a series of mucin genes have been identified. MUC-2 is the predominant mucin expressed in humans. The authors have shown previously in vitro that use of MUC-2 can prevent bacterial translocation. Based on this, it was hypothesized that those patients with Hirschsprung's disease (HD) would have an abnormal production of MUC-2 compared with normal patients.

METHODS

Fresh stool specimens were collected from children with a diagnosis of HD (with or without HAEC) and from age-matched control patients. Protein was extracted, and MUC-2 was detected with Western blot analysis. MUC-2 protein expression was quantified by densitometry measurements. Results are expressed as mean density +/- SD. Statistical comparison was done with unpaired t tests, with P less than.05 being considered significant.

RESULTS

MUC-2 expression was detected in all control patients (mean density, 121 +/- 47). MUC-2 level was lowest in one child with a viral-induced diarrhea (density = 71). In those patients with HD, levels of MUC-2 protein expression were significantly lower (P <.05) than controls (12 +/- 15 for all HD patients). Levels of MUC-2 were lowest (nondetectable) in 2 HD patients who had clinical evidence of HAEC.

CONCLUSIONS

MUC-2 production is markedly depressed in patients with Hirschsprung's disease and is absent with enterocolitis. This decline in protein expression may result in a decrease in epithelial barrier function and be a predisposing factor in the development of HAEC.

Significance of novel endothelin-B receptor gene polymorphisms in Hirschsprung's disease: predominance of a novel variant (561C/T) in patients with co-existing Down's syndrome

Several genes have been implicated in the pathogenesis of Hirschsprung's disease (HSCR). In a previous study performed, five novel (V202M, E480K, IVS10-2A/G, D771N, IVS19-9C/T) mutations and one previously described mutation (P937L) have been identified in the RET proto-oncogene in 20% of the study population. To further investigate the involvement of other genes, mutation analysis of the endothelin-B receptor (EDNRB) gene was performed in 52 unrelated sporadic HSCR patients, including 38 non-syndromic and 14 patients with HSCR and Down's syndrome. Six novel (178G/A, 552C/T, 561C/T, 702C/T, IVS3-6C/T and IVS4 + 3A/G) sequence variants and one previously described (831G/A) polymorphism were identified. Statistically significant differences were achieved for six (178G/A, 552C/T, 561C/T, 702C/T, IVS3-6C/T and 831G/A) of these variants. The T-allele of the 561C/T polymorphism was over represented in the HSCR/Down's syndrome patient group (36% representing 5 of 14) compared to normal controls (6% representing 5 of 84) (p < 0.002, chi(2) with Yates correction = 12.14), suggesting that the 561C/T variant is associated with a low penetrance effect in patients with this complex phenotype. Detection of the 178G/A polymorphism in only non-syndromic HSCR patients, provide further support for an important role of specific sequence variants in the EDNRB gene in the HSCR/Down's syndrome phenotype.

Role of nitric oxide in the internal anal sphincter of Hirschsprung's disease

It is not clear what contribution the internal anal sphincter (IAS) makes to the impaired motility observed in patients with Hirschsprung's disease (HD). Nitric oxide (NO) has recently been shown to be a neurotransmitter in the nonadrenergic noncholinergic (NANC) inhibitory nerves in the human gut. To clarify the physiologic significance of NO in the IAS of HD (aganglionosis), we investigated the enteric nerve responses on lesional (aganglionic) and normal IAS muscle strips above the dentate line. Lesional and normal IAS muscle strips above the dentate line were derived from patients with HD (10 cases) and patients who underwent rectal amputation for low rectal cancer (12 cases). A mechanographic technique was used to evaluate in vitro muscle responses to electrical field stimulation (EFS) before and after treatment with various autonomic nerve blockers, N(G)-L-nitroarginine, and L-arginine. The following results were obtained: (1) Cholinergic nerves are mainly involved in the regulation of enteric nerve responses to EFS in the normal IAS. (2) The aganglionic IAS of patients with HD was more strongly innervated by cholinergic nerves than the normal IAS (p < 0.05). (3) NANC inhibitory nerves were found to act on the normal IAS but had no effect on the enteric nerves in patients with aganglionosis. (4) NO was found to act on normal IAS, but no effect was observed in the aganglionic IAS. These findings suggest that innervation of the cholinergic nerves and a loss of NO mediation of NANC inhibitory nerves play an important role in the impaired motility observed in the IAS with HD.

[Minimally invasive surgery in the treatment of Hirschsprung disease]

STUDY AIM

The treatment of Hirschsprung's disease was improved by the laparoscopic approach. The study aim was to report the results of a short series.

PATIENTS AND METHOD

From December 1996 to January 2000, 13 children (7 boys and 6 girls) were operated for a Hirschsprung's disease with a laparoscopic approach. The mean age at the time of surgery was 6 months. A colostomy had been performed previously in 10 of them. The colostomy was closed and the colorectal anastomosis was performed with Duhamel's technique in 10 and Swenson's in 3. Location of aganglionnic bowel was rectum and sigmoid colon (n = 9) rectum (n = 2) left colon (n = 1), left colon and right transverse colon (n = 1).

RESULTS

The mean duration of the procedure was 160 minutes. One conversion to laparotomy was necessary. One postoperative leak required a temporary colostomy. One intestinal occlusion due to an incarceration of an intestinal loop behind the pulled through colon, required a reoperation. The mean 26 month-follow-up was too short to draw conclusions about functional results.

CONCLUSION

Laparoscopic approach was an important progress in the treatment of the Hirschsprung's disease but, more recently, the transanal approach that we used in the last five patients, seems to be another more important innovation.

Novel RET mutations in Hirschsprung's disease patients from the diverse South African population

Hirschsprung's disease (HSCR) is a common cause of intestinal obstruction in neonates with an incidence of one in 5000 live births. The disease occurs due to the absence of parasympathetic neuronal ganglia in the hindgut, resulting in irregular or sustained contraction of the affected segment. DNA samples of 40 unrelated subjects with HSCR were subjected to mutation screening of the RET (REarranged during Transfection) proto-oncogene, the major susceptibility gene for HSCR. Five novel (V202M, E480K, IVS10-2A/G, D771N, IVS19-9C/T) and one previously described mutation (P973L) were identified. Only two of the mutation-positive patients (from different ethnic groups) displayed total colonic aganglionosis, and both were heterozygous for mutation D771N. The potential disease-causing mutations occurred in 20% of individuals, with more males (22.5% representing seven of 31 males) affected than females (12.5% representing one of eight females). This study represents the first comprehensive genetic analysis of this disease in the diverse South African population.

Hirschsprung's disease: diagnosis and management in children

Hirschsprung's disease is a congenital abnormality of the bowel that results in loss of peristalsis, and is one of the main reasons why an infant may require a stoma soon after birth. Various stages of surgery may be required to resect the affected part of the bowel, including formation and closure of the stoma. Following surgery, the perception of many families is that their child is now "normal" and that all previous problems of managing their child are now resolved. However, there are a variety of postoperative complications and issues relating to bowel control which can affect the child in the long term. This article looks at how potential postoperative long-term problems can be identified early, and thus minimized, by healthcare staff being aware of possible problems, taking a proactive approach to management and advising families about the issues involved.

Immunolocalization of the gap junction protein Connexin43 in the interstitial cells of Cajal in the normal and Hirschsprung's disease bowel

BACKGROUND

Interstitial cells of Cajal (ICC) are pacemaker cells between gastrointestinal smooth muscles; they generate spontaneous slow waves of the smooth muscle layers and mediate neurotransmission. The cellular network of ICC is connected by Gap junctions to each other and to the smooth muscle cells. Although there have been several studies reporting distribution of ICC in the normal bowel and pathological conditions such as Hirschsprung's disease, there is little information on the crucial role of Gap junctions in the intercellular communication in the gut musculature. The aim of this study was to investigate the immunolocalization of the Gap junction protein Connexin43 in the normal and Hirschsprung's disease (HD) bowel using whole-mount preparation technique and confocal laser scanning microscopy.

METHODS

Full-thickness bowel specimens were collected at pull-through operation from 8 patients diagnosed as having HD. Normal control large bowel specimens were collected from 12 patients during bladder augmentation operation. Whole-mount preparation was performed on all specimens and double immunostaining was carried out using anti c-kit and antiConnexin43 antibodies. The immunolocalization was detected with the help of confocal laser scanning microscopy.

RESULTS

Connexin43 immunoreactivity appeared in and between the c-kit-positive cells and along the smooth muscle fibers of the normal bowel and ganglionic part of HD bowel. In the aganglionic part of HD bowel there was no expression of Connexin43. In the transitional zone of HD the Connexin43 staining was weak and colocalized only in the processes of the c-kit-positive Cajal cells.

CONCLUSIONS

Results of this study show for the first time that Gap junctional protein Connexin43 is present in the ICCs, which form a 3-dimensional network in the normal bowel wall. The lack of expression of Connexin43 in the aganglionic bowel and reduced expression in the transitional zone of HD suggest that the impaired intercellular communication between ICCs and smooth muscle cells may partly be responsible for the motility dysfunction in HD.

Marked morphological differences in the myenteric plexus between the mesenteric and antimesenteric sides of small bowel in premature infants

BACKGROUND

The gastrointestinal tract appears morphologically prepared for oral feeding by the end of the second trimester, but many of the physiological processes required for efficient enteral nutrition are not developed fully until 33 to 34 weeks' gestation. Myenteric plexus is well recognized as an important regulator of peristaltic activity. Whole-mount preparation technique produces a 3-dimensional picture to better show the neuronal networks branching and interconnections. The aim of this study was to investigate neurone density and morphology of the myenteric plexus in premature infants using whole-mount technique.

METHODS

Full-thickness small and large bowel specimens were collected at autopsy from 6 premature babies (gestational age, 26 to 32 weeks) who died without evidence of gastrointestinal disease. Whole-mount preparation of the myenteric plexus was made and stained with NADPH-diaphorase and Acetylcholinesterase (AChE) histochemistry. The stained myenteric network was measured with a computer image analysis system. Controls included 4 full-term babies who died of nongastrointestinal disease.

RESULTS

In premature infants there were striking differences in neuronal density of myenteric plexus in the mesenteric and antimesenteric border of small bowel. The differences in neuronal density in mesenteric and antimesenteric border of small bowel gradually became less striking as the gestation progressed with no differences evident at gestational age 32 weeks.

CONCLUSIONS

This study shows for the first time that the neurone density of myenteric plexus is significantly higher in the mesenteric border of the small bowel compared with antimesenteric border in premature infants. The marked morphological differences observed in neurone density in the small bowel of premature infants may contribute to immature small bowel activity.

Altered endothelin-3 and endothelin-B receptor mRNA expression in Hirschsprung's disease

BACKGROUND

Recently, the endothelin-3 (EDN3) and endothelin-B receptor (EDNRB) gene have been recognized as susceptibility genes for Hirschsprung's disease (HD). However, gene mutations have been observed only in limited cases, and the role of EDN3 in the pathogenesis and motility dysfunction in HD is not understood fully. To evaluate the possible implication of EDN3 and EDNRB for the development of HD, we examined the EDN3 and EDNRB mRNA level in bowel specimens of HD patients.

METHODS

Entire resected specimens of colon were obtained from 14 patients with HD. Eight age-matched control patients without gastroenteric disorders also were examined. mRNA was extracted from ganglionic and aganglionic segments of the HD specimens and normal colons. Reverse transcription-polymerase chain reaction (RT-PCR) was performed to evaluate the relative amount of EDN3 and EDNRB mRNA.

RESULTS

In normal colon, constant EDN3 and EDNRB mRNA expression was observed. In HD, EDN3 and EDNRB mRNA expression was observed. In HD, EDN3 and EDNRB mRNA levels were decreased both in ganglionic and aganglionic segment in 2 cases. In 6 cases, EDN3 mRNA expression was decreased in aganglionic segment and in another 2 cases, EDNRB mRNA expression was decreased in aganglionic segment. In the remaining 4 cases, EDN3 and EDNRB mRNA levels were similar to controls.

CONCLUSION

The authors' findings indicate that loss of EDN3 and EDNRB function may be involved in the maldevelopment of neural crest-derived cells causing HD in many patients.

Mast cells and gut nerve development: implications for Hirschsprung's disease and intestinal neuronal dysplasia

BACKGROUND/PURPOSE

In Hirschsprung's disease (HD), the aganglionic bowel is characterized by the presence of hypertrophic nerve trunks and increased numbers of adrenergic and cholinergic nerve fibers. Intestinal neuronal dysplasia (IND), if associated with HD, occurs proximal to the aganglionic segment in HD, and is characterized by dysplasia of parasympathetic nerves, hyperganglionosis, and giant ganglia. However, the cause of such abnormalities in HD and IND is unclear. Recent reports that mast cells (MC) have been observed in direct contact with nerve fibers generally, suggest that MC are essential for nerve growth and repair. MC synthesize, store, and release nerve growth factor (NGF). NGF supports the development and functional maintenance of sympathetic and cholinergic neurons. The aim of this study was to examine the colonic distribution of MC with respect to nerves in HD and HD associated with IND.

METHODS

MC and NGF were examined immunohistochemically in ganglionic, transitional, and aganglionic segments of colon from 20 patients with HD (five patients associated with IND) and 15 age-matched controls. MC were counted in each of five random fields using light microscopy (x100).

RESULTS

Interestingly, aganglionic and IND segments had large numbers of MC in all layers compared with ganglionic segments in HD patients and controls (P< .0001). The number of MC in transitional segments was significantly less compared with ganglionic segments in HD patients and controls (P< .01). MC stained positively for NGF, and some were found in contact with abnormal hypertrophic nerve trunks in HD and giant ganglia in IND.

CONCLUSIONS

MC may cause hypertrophic nerve trunks and giant ganglia by releasing NGF and also may be an important factor in the excessive development of cholinergic and adrenergic nerve fibers in HD and IND.

Point nucleotidic changes in both the RET proto-oncogene and the endothelin-B receptor gene in a Hirschsprung disease patient associated with Down syndrome

A short-segment Hirschsprung disease (HSCR) patient associated with 21 trisomy showing point nucleotidic changes in both the receptor tyrosine kinase (RET) proto-oncogene and the endothelin-B receptor (EDNRB) gene is reported. A T to A heterozygous transition at the splicing donor site of the intron 10 in the RET proto-oncogene, and a G to A heterozygous substitution in non-coding region in the exon 1 of the EDNRB gene were observed. The familial analysis with these genes revealed that the origin of the former mutation was de novo and the latter one was maternal. No patient has been reported with two points mutations in different pathogenetically susceptible loci for HSCR. There is genetic evidence that the RET and EDNRB genes may interact in their susceptibility leading to HSCR.

Ionizing radiation and genetic risks IX. Estimates of the frequencies of mendelian diseases and spontaneous mutation rates in human populations: a 1998 perspective

This paper is focused on baseline frequencies of mendelian diseases and the conceptual basis for calculating doubling doses both of which are relevant for the doubling dose method of estimating genetic risks of exposure of human populations to ionizing radiation. With this method, the risk per unit dose is obtained as a product of three quantities, namely, the baseline frequency of the disease class under consideration, the relative mutation risk (which is the reciprocal of the doubling dose, which in turn, is calculated as a ratio of spontaneous and induction rates of mutations) and mutation component, i.e., the responsiveness of the disease class to an increase in mutation rate. The estimates of baseline frequencies of mendelian diseases that are currently used in risk estimation date back to the late 1970s. Advances in human genetics during the past two decades now permit an upward revision of these estimates. The revised estimates are 150 per 10(4) livebirths for autosomal dominants (from the earlier estimate of 95 per 10(4)), 75 per 10(4) livebirths for autosomal recessives (from 25 per 10(4)) and to 15 per 10(4) livebirths for X-linked diseases (from 5 per 10(4)). The revised total frequency of mendelian diseases is thus 240 per 10(4) livebirths and is about twice the earlier figure of 125 per 10(4) livebirths. All these estimates, however, pertain primarily to Western European and Western European-derived populations. The fact that in several population isolates or ethnic groups, some of these diseases (especially the autosomal recessives) are more common as a result of founder effects and/or genetic drift is well known and many more recent examples have come to light. These data are reviewed and illustrated with data from studies of the Ashkenazi Jewish, Finnish, French Canadian, Afrikaner and some other populations to highlight the need for caution in extrapolating radiation risks between populations. The doubling dose of 1 Gy that has been used for the past 20 years for risk estimation is based on mouse data for both spontaneous and induction rates of mutations. In extrapolating the mouse-data-based doubling dose to humans, it is assumed that the spontaneous rates in mice and humans are similar. This assumption is incorrect because of the fact that in humans, for several well-studied mendelian diseases, the mutation rate differs between the two sexes and it increases with paternal age. In estimates of spontaneous mutation rates in humans (which represent averages over both sexes), however, paternal age effects are automatically incorporated. In the mouse, these effects are expected to be much less (if they exist at all), but the problem has not been specifically addressed. The complexities and uncertainties associated with assessing the potential impact of spontaneous mutations which arise as germinal mosaics (and which can result in clusters of mutations in the following generation) on mutation rate estimates (in the mouse) and on mutation rate estimates and disease frequencies (in humans) are discussed. In view of (i) the lack of comparability of spontaneous mutation rates in mice and humans and (ii) the fact that these estimates for human genes already include both paternal age effects and correction for clusters (if they had occurred), it is suggested that a prudent procedure now is to base doubling dose calculations on spontaneous mutation rates of human genes (and induction rates of mouse genes, in the absence of a better alternative). This concept, however, is not new and was used by the US National Academy's Committee on the Biological Effects of Ionizing Radiation in its 1972 report.

Genetic aspects of Hirschsprung's disease

Hirschsprung's disease (HD) is a relatively common cause of intestinal obstruction in the newborn, characterized by the absence of autonomic ganglion cells in the terminal bowel. Existence of familial cases indicates that genetic factors may be involved in the etiology of some cases of HD. Different inheritance patterns observed in subsets of HD families or kindreds, and the detection of different chromosome aberrations in some HD patients, suggest genetic heterogeneity of HD. Recent expansion of molecular genetics has identified multiple susceptibility genes of HD. These include the RET gene, the glial cell-derived neurotrophic factor gene, the endothelin-B receptor gene, and endothelin-3 gene. Furthermore, some other genes or genetic factors are speculated to be implicated in the development of HD, and it is believed that multiple factors play a role in disease development in some cases. Taken together, these data suggest and may explain the complexity of the etiology of HD. This review focuses on recent advances in our understanding of the genetic aspects of HD.

Hirschsprung's disease: a 20-year experience

During the period from 1972 to 1992, 59 children received surgical treatment at the University of Louvain Medical School for biopsy-proven Hirschsprung's disease (HD). The extent of aganglionosis was as follows: short segment restricted to the rectosigmoid or descending colon (n = 44, 75%); long segment (n = 9,15%); ultra-short segment (n = 3, 5%); unknown length because of death without autopsy (n = 3, 5%). The median age at operation was 7 months for short-segment disease compared with 14 months for those with long-segment disease. Surgical procedures used for short-segment disease were Swenson with colostomy (n = 16), Swenson-Pellerin without colostomy (n = 27), Duhamel (n = 1), and for long-segment disease were Martin (n = 3), Swenson-Deloyers (n = 2), Swenson-Boley (n = 2) and ileostomy only in = 2). Lynn's sphincteromyotomy was performed in the three ultra-short cases. There were six deaths (10%) at a median age of 86 days (range, 28 to 1545 days), three had long-segment disease, and the others were not classified because of death before curative surgery. Enterocolitis (EC) was the most common cause of death (five cases) and was also the major source of morbidity after curative surgery (12 of 44, 27%) in short-segment patients, three of seven (43%) in long-segment patients. The functional success of the procedure was evaluated in 70% of the surviving patients (37 of 53; mean follow-up, 8.7 years; range, 1.2 to 21.5), using a novel semiquantitative scoring system, specifically designed for children who have HD. This system assesses normal stool evacuation, abdominal distention, soiling, and severe incontinence. The results were compared with those from a population of 39 healthy children and adolescents and demonstrated progressive improvement in function during childhood and adolescence (P = .04) for patients treated for short-segment disease. However, function was found to be consistently poorer in all age groups when compared with healthy controls (5 to 10 years, P < .01; 10 to 15 years, P < .05; > 15 years, P < .01).

Long-term stooling patterns in infants undergoing primary endorectal pull-through for Hirschsprung's disease

Primary endorectal pull-through (ERPT) has become an increasingly popular method of caring for neonates and young infants who have Hirschsprung's disease. This study evaluated the long-term stooling patterns and continence rates of patients who had a primary ERPT as a young infant. The records of 24 infants who underwent a primary ERPT for Hirschsprung's disease were reviewed. The patients' families (those patients over 3 years of age, n = 12) underwent a detailed interview that graded continence from 0 (poor) to 10 (normal). Mean age at ERPT was 15 +/- 17 days (range, 2 to 67). Mean follow-up was 1,036 +/- 614 days. Nine patients suffered from 20 episodes of enterocolitis. Stooling frequency declined rapidly in the first 6 months after the ERPT (r2 = 1.00) and more slowly after this time (r2 = 0.79). Continence was graded as normal (10) in one, good (6 to 9 points) in nine, and fair (1 to 5) in two patients, both of whom had total colonic disease. The authors conclude that a primary ERPT in the young infant who has Hirschsprung's disease can yield excellent results including normalization of stooling frequency and good to excellent levels of continence.

Mutation analysis of the RET, the endothelin-B receptor, and the endothelin-3 genes in sporadic cases of Hirschsprung's disease

To date, three genes have been identified as susceptibility genes for Hirschsprung's disease (HSCR), the RET proto-oncogene, the endothelin-B receptor gene (EDNRB) and the endothelin-3 gene (EDN3). However, the question of whether these genes play a role in sporadically occurring HSCR has not been fully clarified. In this study, the authors performed mutation analysis of these three genes in 41 sporadic HSCR patients without any family history by using single-strand conformational polymorphism or denaturing gradient gel electrophoresis methods. Exon 2, 3, 5, 6, 12, 13, 15, and 17 of the RET gene, 7 exons of the EDNRB gene, and the region of the EDN3 gene including sequences corresponding to proteolytic cleavage sites and mature endothelin-3 were analysed. By direct sequencing, three causative RET mutations were confirmed; a Phe to Ser substitution at codon 174, a Cys to Tyr substitution at codon 197, and a point mutation at the splice acceptor site of intron 12, in patients with aganglionosis confined to the rectosigmoid colon, the transverse colon, and the total colon, respectively. In the EDNRB locus, two mutations were observed; a nonsense mutation of Trp to stop at codon 275, and a T insertion at nucleotide 878, in patients with aganglionosis confined to the rectosigmoid colon, and the descending colon, respectively. No mutation was detected in the EDN3 gene. Mutation rates were 7.3% in the RET and 5% in the EDNRB gene. Our data indicate that RET and EDNRB mutations have a role in the aetiology of some sporadically occurring HSCR. However, the low mutation rate of susceptibility genes in sporadically occurring HSCR suggests that other genes or environmental factors are involved in the development of the disease.