Advances in understanding functional variations in the Hirschsprung disease spectrum (variant Hirschsprung disease)

Hirschsprung Disease and Intestinal Neuronal Dysplasia Type B: Is There a Difference in the Clinical Presentation of These Two Diseases?

BACKGROUND

Although the signs and symptoms that comprise the clinical presentation of Hirschsprung disease (HD) and intestinal neuronal dysplasia type B (IND-B) are well established, no studies have specifically compared the clinical characteristics presented by patients with these diseases. We compared the clinical pictures of patients with HD and IND-B at the time of histopathological diagnosis.

METHODS

This was a single-center, retrospective, analytical, and comparative study. We included 119 patients aged 0-15 years diagnosed with HD or IND-B. Information from the medical records of these patients was retrieved to obtain demographic and clinical information at the time of diagnosis. The data were compared statistically according to the characteristics of the variables.

RESULTS

Sixty-nine patients (58.0%) were diagnosed with HD, and 50 (42.0%) had IND-B. The HD group had significantly more individuals with symptom onset in the neonatal period (p = 0.001), delayed meconium clearance (p < 0.001), failure to thrive (p = 0.02), and acute complications, such as enterocolitis (p = 0.049) or acute abdominal obstruction (p = 0.031), more commonly requiring emergency surgery (p < 0.001). Patients with IND-B were diagnosed at a significantly older age (p = 0.002). They more commonly had chronic constipation as their main symptom (p = 0.004), with local complications, such as evacuation bleeding (p = 0.007).

CONCLUSION

There were significant differences between the clinical pictures of patients with HD and IND-B. Knowledge of each disease's most common signs and symptoms can help direct diagnostic susception and initial management.

Diagnostic utility of Bcl-2 immunohistochemical expression in pediatric functional bowel obstruction cases with ganglionated specimens

Background

Functional disturbances of the gastrointestinal tract are caused by a number of neurodysplastic conditions, including diseases that are rarer than Hirschsprung’s disease (HSCR), such as ganglion cell immaturity and intestinal neuronal dysplasia (IND). Bcl-2 shows positive immunoreactivity in degenerative and immature ganglion cells (IGCs). This work evaluates the implication of the immunohistochemical expression of Bcl-2 in cases of pediatric intestinal pseudo-obstruction (IPO) with ganglionated specimens.

This 2-year prospective observational study was conducted from January 2017 to December 2019 on all intestinal specimens for cases referred from a pediatric surgery department with clinical data suggesting IPO (abdominal distension > 3 months, intermittent bilious vomiting, no radiological evidence of the transitional zone of HSCR or evidence of mechanical obstruction). The exclusion criteria were patients with IPO related to myopathic disorders, aganglionic biopsies, and specimens with inadequate tissue blocks. The same number of intestinal specimens of cases without IPO was used as a control group. All specimens underwent a histologic examination of ganglion cells and nerve bundles and were also evaluated for Bcl-2 immunohistochemical expression.

Results

Twenty-one specimens were analyzed, including six colonic resection specimens and 15 intestinal biopsies taken by full-thickness transanal biopsy (n = 12) or incisional biopsy from inadequately functioning stomas (n = 3). The mean ± standard deviation age of the patient cohort was 22 ± 7.4 months (range, 19–153 months), and there were 13 (61.9%) male patients. Bcl-2 protein was strongly positive in 57.1% of the cases, weakly positive in 19%, and negative in 23.8% as well as in all 21 control specimens. A highly significant correlation was observed between Bcl-2 expression and ganglion cell number (P < 0.001), where all hyperganglionic specimens showed strong positivity compared with the hypoganglionic and adequately ganglionic specimens. A positive association was also found between Bcl-2 expression and IND compared with other disorders of dysganglionosis (P = 0.04) and post-HSCR cases (P = 0.002).

Conclusion

Bcl-2 immunohistochemistry is a valuable tool to diagnose allied disorders of HSCR through its expression in IGCs, which are difficult to identify by conventional hematoxylin and eosin staining.

Diagnostic Algorithm in Hirschsprung's Disease: Focus on Immunohistochemistry Markers

BACKGROUND/AIM

Hirschsprung disease (HD) is caused by the congenital absence of ganglion cells in the distal bowel (aganglionosis). Rectal biopsy is considered important for its diagnosis. The aim of this study was to apply immunohistochemical staining using a minimal set of antibodies and develop an algorithm that will assist in the diagnosis of HD.

PATIENTS AND METHODS

Rectal or colonic biopsies were performed in patients with HD (n=26) or patients treated for other bowel diseases (n=34). Immunohistochemical staining was performed for MAP1b, peripherin, S-100, calretinin, NSE, bcl-2 and CD56 proteins.

RESULTS

Staining for CD56, S-100, peripherin and calretinin facilitated the identification of ganglion cells. The use of CD56 and S-100 antibodies together resulted in the highest rate of ganglion cell staining intensity (94%).

CONCLUSION

We propose a practical diagnostic algorithm with the application of CD56 and S-100 antibodies that can be used in clinical practice in children suspected of Hirschsprung's disease.

RET compound inheritance in Chinese patients with Hirschsprung disease: lack of penetrance from insufficient gene dysfunction

Hirschsprung disease (HSCR) is a neurocristopathy characterized by the absence of enteric ganglia along variable lengths of the intestine. Genetic defects play a major role in HSCR pathogenesis with nearly 50% of patients having a structural or regulatory deficiency in the major susceptibility gene RET. However, complete molecular defects remain poorly characterized in most patients. Here, we performed detailed genetic, molecular, and populational investigations of rare null mutations and modifiers at the RET locus. We first verified the pathogenicity of three RET splice site mutants (c.1879 + 1G > A, c.2607 + 5G > A and c.2608-3C > G) at the RNA level. We also identified significantly higher risk allele (genotype) frequencies, and their over-transmission, from unaffected parents to affected offspring of three functionally independent enhancer variants (rs2506030, rs7069590 and rs2435357, with odd ratios (OR) of 2.09, 2.71 and 7.59, respectively, P < 0.001). These three common variants are in significant (P < 4.64 × 10^-186) linkage disequilibrium in the Han Chinese population with ~ 60% of them carrying at least one copy and > 10% with two copies. We show that RET compound inheritance of rare and common variants prevails in 64% (seven out of 11) of Chinese HSCR families. This study supports the idea that common RET variants can modify the penetrance of rare null RET mutations in HSCR, and the combined high susceptibility allele dosage may constitute the unique raised "risk baseline" among the Chinese population.

Hirschsprung's Disease-Recent Understanding of Embryonic Aspects, Etiopathogenesis and Future Treatment Avenues

Hirschsprung's disease is a neurocristopathy, caused by defective migration, proliferation, differentiation and survival of neural crest cells, leading to gut aganglionosis. It usually manifests rapidly after birth, affecting 1 in 5000 live births around the globe. In recent decades, there has been a significant improvement in the understanding of its genetics and the association with other congenital anomalies, which share the pathomechanism of improper development of the neural crest. Apart from that, several cell populations which do not originate from the neural crest, but contribute to the development of Hirschsprung's disease, have also been described, namely mast cells and interstitial cells of Cajal. From the diagnostic perspective, researchers also focused on "Variants of Hirschsprung's disease", which can mimic the clinical signs of the disease, but are in fact different entities, with distinct prognosis and treatment approaches. The treatment of Hirschsprung's disease is usually surgical resection of the aganglionic part of the intestine, however, as many as 30-50% of patients experience persisting symptoms. Considering this fact, this review article also outlines future hopes and perspectives in Hirschsprung's disease management, which has the potential to benefit from the advancements in the fields of cell-based therapy and tissue engineering.

Long-term outcomes of single-incision laparoscopic technique in Soave procedure compared with heart-shaped anastomosis for Hirschsprung disease

PURPOSE

This retrospective study compared the long-term outcomes of single-incision laparoscopy-assisted Soave procedure (SILSP) with single-incision laparoscopy-assisted heart-shaped anastomosis (SILHSA) in patients with Hirschsprung disease (HSCR).

METHODS

Patients diagnosed with HSCR that underwent SILSP or SILHSA between January 2009 and January 2015 at our institute were enrolled in this retrospective study. Data on the clinical characteristics, perioperative complications, and postoperative quality of life were retrospectively collected and analyzed.

RESULTS

There were 109 patients in the SILSP group and 95 patients in the SILHSA group. No differences in clinical characteristics, including age, weight, hospitalization length, blood loss volume, and operation time, were noted between the two groups. The incidence rates of constipation and soiling were lower in the SILHSA group than those in the SILSP group. The SILHSA group showed lower scores in constipation and soiling compared with the SILSP group, indicating a better surgical outcome for patients receiving SILHSA procedure.

CONCLUSION

SILHSA is a feasible and reliable minimally invasive surgical procedure for patients with HSCR. Patients who underwent SILHSA had lower incidence rates of constipation and soiling than patients who underwent SILSP, suggesting that SILHSA could be a better choice for patients with HSCR.

A novel PHOX2B gene mutation in an extremely low birth weight infant with congenital central hypoventilation syndrome and variant Hirschsprung's disease

Congenital central hypoventilation syndrome is a disorder of respiratory control caused by mutations in the paired-like homeobox 2B gene. Mutations in the paired-like homeobox 2B gene are also responsible for Hirschsprung's disease. Variant Hirschsprung's disease is a rarer disorder that does not meet the diagnostic criteria of Hirschsprung's disease, although severe functional bowel obstruction persists. We present a case of an extremely low birth weight infant with congenital central hypoventilation syndrome and variant Hirschsprung's disease. A male infant who was diagnosed to have fetal growth restriction and polyhydramnios was delivered by emergency cesarean section at 30 weeks and 3 days of gestational age due to non-reassuring fetal status. The birth weight was 979 g, and intensive care was started immediately following delivery. The patient exhibited refractory apnea and was diagnosed with congenital central hypoventilation syndrome by genetic testing of the paired-like homeobox 2B gene. The patient also exhibited refractory functional bowel obstruction and was diagnosed to have variant Hirschsprung's disease through pathological examination of his intestinal specimens. The patient grew slowly but surely with intensive care including mechanical ventilation and parenteral nutrition. However, the patient repeatedly suffered from sepsis and died of fungemia at 197 days of age. This is the first congenital central hypoventilation syndrome case that was accompanied with variant Hirschsprung's disease, and the paired-like homeobox 2B mutation detected in this case (NM_003924.3: c.441G > C; p.(Gln147His)) is novel. This case suggests that the paired-like homeobox 2B mutation causes not only congenital central hypoventilation syndrome and Hirschsprung's disease, but also variant Hirschsprung's disease in humans. It also highlights the extreme difficulty in treating premature infants with severe and prolonged functional bowel obstruction.

Waardenburg syndrome with isolated deficiency of myenteric ganglion cells at the sigmoid colon and rectum

Waardenburg syndrome (WS) has the characteristic clinical features caused by the embryologic abnormality of neural crest cells. WS patients sometimes suffer from functional intestinal obstruction. When it is Hirschsprung disease (HD), the WS is diagnosed as type 4 WS. We report a case of WS which did not have myenteric ganglion cells in the sigmoid colon and rectum. Whether to diagnosis this case as type 1 or 4 WS is controversial. Moreover, this is the third report which has peristalsis failure caused by abnormal myenteric plexus. In all three cases, the eosinophils had aggregated in the myenteric layer of the transition zone. During embryonic life, enteric ganglion cells migrate to the myenteric layer from the proximal to the distal side sequentially and, subsequently, to the submucosal layer through the circular muscle. Therefore, we hypothesize that myenteric ganglion cells that had already migrated were eliminated by an eosinophil-mediated mechanism in these three cases. We believe this report may be helpful to elucidate the pathogenesis of some types of HD.

RET somatic mutations are underrecognized in Hirschsprung disease

PURPOSE

We aimed to determine the frequency of RET mosaicism in Hirschsprung disease (HSCR), test whether it has been underestimated, and to assess its contribution to HSCR risk.

METHODS

Targeted exome sequencing (n = 83) and RET single-gene screening (n = 69) were performed. Amplicon-based deep sequencing was applied on multiple tissue samples. TA cloning and sequencing were conducted for validation.

RESULTS

We identified eight de novo mutations in 152 patients (5.2%), of which six were pathogenic mosaic mutations. Two of these patients were somatic mosaics, with mutations detected in blood, colon, and saliva (mutant allele frequency: 35-44%). In addition, germ-line mosaicism was identified in four clinically unaffected subjects, each with an affected child, in multiple tissues (mutant allele frequency: 1-28%).

CONCLUSION

Somatic mutations of the RET gene are underrecognized in HSCR. Molecular investigation of the parents of patients with seemingly sporadic mutations is essential to determine recurrence risk in these families.

Cell therapy for GI motility disorders: comparison of cell sources and proposed steps for treating Hirschsprung disease

Cell therapeutic approaches to treat a range of congenital and degenerative neuropathies are under intense investigation. There have been recent significant advancements in the development of cell therapy to treat disorders of the enteric nervous system (ENS), enteric neuropathies. These advances include the efficient generation of enteric neural progenitors from pluripotent stem cells and the rescue of a Hirschsprung disease model mouse following their transplantation into the bowel. Furthermore, a recent study provides evidence of functional innervation of the bowel muscle by neurons derived from transplanted ENS-derived neural progenitors. This mini-review discusses these recent findings, compares endogenous ENS-derived progenitors and pluripotent stem cell-derived progenitors as a cell source for therapy, and proposes the key steps for cell therapy to treat Hirschsprung disease.