Variants of the ACTG2 gene correlate with degree of severity and presence of megacystis in chronic intestinal pseudo-obstruction.
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ABSTRACT:
SUBMITTER: Matera I
PROVIDER: S-EPMC4970688 | biostudies-literature | 2016 Aug
REPOSITORIES: biostudies-literature
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Project description:OBJECTIVES:The diagnosis of chronic intestinal pseudo-obstruction has depended on clinical features, manometry, and imaging. This report aimed to determine the efficacy of sequencing the actin ?-2 (ACTG2) gene for diagnosis. In addition, the goal was to determine how often a mutation would be found in our randomly collected cohort of probands and those probands published previously. METHODS:Whole exome sequencing was performed in 4 probands with chronic intestinal pseudo-obstruction. Subsequently, only the ACTG2 gene was sequenced in another 24 probands (total 28). We analyzed published data of 83 probands and our 28 (total 111) and determined how many had pathogenic variants and the precise genotype. RESULTS:Whole exome and Sanger sequencing revealed a pathogenic variant in the ACTG2 gene in 4 out of 28 of our probands and in 45 out of 83 published probands (49/111 [44.1%]). Moreover, a mutational hotspot in the ACTG2 gene was recognized. Genetic heterogeneity is evident. CONCLUSIONS:Pooled gene sequencing results from 1 individual in each of 111 families enabled a precise diagnosis of an ACTG2 mutation in 49 (44%). The benefit to patients and families of early confirmation of a motility disorder not only helps avoid unnecessary intervention, but also enables institution of appropriate treatments and avoidance of secondary disorders such as malnutrition and poor growth. Knowledge of a pathogenic variant in a parent, with a 50% risk of recurrence, provides an opportunity for genetic counseling.
| S-EPMC5610062 | biostudies-literature
Project description:Megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS) is a rare disorder of enteric smooth muscle function affecting the intestine and bladder. Patients with this severe phenotype are dependent on total parenteral nutrition and urinary catheterization. The cause of this syndrome has remained a mystery since Berdon's initial description in 1976. No genes have been clearly linked to MMIHS. We used whole-exome sequencing for gene discovery followed by targeted Sanger sequencing in a cohort of patients with MMIHS and intestinal pseudo-obstruction. We identified heterozygous ACTG2 missense variants in 15 unrelated subjects, ten being apparent de novo mutations. Ten unique variants were detected, of which six affected CpG dinucleotides and resulted in missense mutations at arginine residues, perhaps related to biased usage of CpG containing codons within actin genes. We also found some of the same heterozygous mutations that we observed as apparent de novo mutations in MMIHS segregating in families with intestinal pseudo-obstruction, suggesting that ACTG2 is responsible for a spectrum of smooth muscle disease. ACTG2 encodes γ2 enteric actin and is the first gene to be clearly associated with MMIHS, suggesting an important role for contractile proteins in enteric smooth muscle disease.
| S-EPMC3967950 | biostudies-literature
Project description:BACKGROUND/AIMS: Chronic intestinal pseudo-obstruction (CIPO) reflects a dysfunction of the visceral smooth muscle or the enteric nervous system. Gastrointestinal manifestations are common in systemic lupus erythematosus (SLE) but CIPO has not been reported. Features of CIPO are reported in five patients with SLE. METHODS: From 1988 to 1993, five patients with SLE or SLE-like syndrome were hospitalised for gastrointestinal manometric studies. CIPO was the onset feature in two cases. Antroduodenal manometry (three hours fasting, two hours fed) was performed in all patients, and oesophageal manometry in four. RESULTS: Intestinal hypomotility associated with reduced bladder capacity and bilateral ureteral distension was found in four patients and aperistalsis of the oesophagus in three. Treatment, which consisted of high dose corticosteroids, parenteral nutrition, promotility agents, and antibiotics, led to remission of both CIPO and urinary abnormalities in all cases. Antroduodenal manometry performed in two patients after remission showed increased intestinal motility. One patient died, and postmortem examination showed intestinal vasculitis. CONCLUSIONS: CIPO in SLE is a life threatening situation that can be reversed by treatment. It may be: (a) a complication or onset feature of the disease; (b) secondary to smooth muscle involvement; (c) associated with ureteral and vesical involvement; (d) the result of intestinal vasculitis.
| S-EPMC1727185 | biostudies-other
Project description:Megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS) is a congenital disorder characterized by loss of smooth muscle contraction in the bladder and intestine. To date, three genes are known to be involved in MMIHS pathogenesis: ACTG2, MYH11, and LMOD1. However, for approximately 10% of affected individuals, the genetic cause of the disease is unknown, suggesting that other loci are most likely involved. Here, we report on three MMIHS-affected subjects from two consanguineous families with no variants in the known MMIHS-associated genes. By performing homozygosity mapping and whole-exome sequencing, we found homozygous variants in myosin light chain kinase (MYLK) in both families. We identified a 7 bp duplication (c.3838_3844dupGAAAGCG [p.Glu1282_Glyfs?51]) in one family and a putative splice-site variant (c.3985+5C>A) in the other. Expression studies and splicing assays indicated that both variants affect normal MYLK expression. Because MYLK encodes an important kinase required for myosin activation and subsequent interaction with actin filaments, it is likely that in its absence, contraction of smooth muscle cells is impaired. The existence of a conditional-Mylk-knockout mouse model with severe gut dysmotility and abnormal function of the bladder supports the involvement of this gene in MMIHS pathogenesis. In aggregate, our findings implicate MYLK as a gene involved in the recessive form of MMIHS, confirming that this disease of the visceral organs is heterogeneous with a myopathic origin.
| S-EPMC5501771 | biostudies-literature
Project description:The retinoblastoma 1 (RB1) tumor suppressor is a critical regulator of cell cycle progression and development. To investigate the role of RB1 in neural crest-derived melanocytes, we bred mice with a floxed Rb1 allele with mice expressing Cre from the tyrosinase (Tyr) promoter. TyrCre+;Rb1fl/fl mice exhibited no melanocyte defects but died unexpectedly early with intestinal obstruction, striking defects in the enteric nervous system (ENS), and abnormal intestinal motility. Cre-induced DNA recombination occurred in all enteric glia and most small bowel myenteric neurons, yet phenotypic effects of Rb1 loss were cell-type specific. Enteric glia were twice as abundant in mutant mice compared with those in control animals, while myenteric neuron number was normal. Most myenteric neurons also appeared normal in size, but NO-producing myenteric neurons developed very large nuclei as a result of DNA replication without cell division (i.e., endoreplication). Parallel studies in vitro found that exogenous NO and Rb1 shRNA increased ENS precursor DNA replication and nuclear size. The large, irregularly shaped nuclei in NO-producing neurons were remarkably similar to those in progeria, an early-onset aging disorder that has been linked to RB1 dysfunction. These findings reveal a role for RB1 in the ENS.
| S-EPMC3859411 | biostudies-literature
Project description:BACKGROUND: Chronic idiopathic intestinal pseudo-obstruction, a syndrome of ineffectual motility due to a primary disorder of enteric nerve or muscle, is rare. AIMS: To determine the clinical spectrum, underlying pathologies, response to treatments, and prognosis in a consecutive unselected group of patients. METHODS: Cross sectional study of all patients with clinical and radiological features of intestinal obstruction in the absence of organic obstruction, associated with dilated small intestine (with or without dilated large intestine), being actively managed in one tertiary referral centre at one time. RESULTS: Twenty patients (11 men and nine women, median age 43 years, range 22-67) fulfilled the diagnostic criteria. Median age at onset of symptoms was 17 years (range two weeks to 59 years). Two patients had an autosomally dominant inherited visceral myopathy. Major presenting symptoms were pain (80%), vomiting (75%), constipation (40%), and diarrhoea (20%). Eighteen patients required abdominal surgery, and a further patient had a full thickness rectal biopsy. The mean time interval from symptom onset to first operation was 5.8 years. Histology showed visceral myopathy in 13, visceral neuropathy in three, and was indeterminate in three. In the one other patient small bowel motility studies were suggestive of neuropathy. Two patients died within two years of symptom onset, one from generalised thrombosis and the other from an inflammatory myopathy. Of the remaining 18 patients, eight were nutritionally independent of supplements, two had gastrostomy or jejunostomy feeds, and eight were receiving home parenteral nutrition. Five patients were opiate dependent, only one patient had benefited from prokinetic drug therapy, and five patients required formal psychological intervention and support. CONCLUSIONS: In a referral setting visceral myopathy is the most common diagnosis in this heterogeneous syndrome, the course of the illness is usually prolonged, and prokinetic drug therapies are not usually helpful. Ongoing management problems include pain relief and nutritional support.
| S-EPMC1891582 | biostudies-other
Project description:Background/aimsNatural history of chronic intestinal pseudo-obstruction (CIPO), a rare disease characterized by episodes of non-mechanical obstruction, is unclear in adults. This study evaluates the clinical course of CIPO and palliative care needs of patients.MethodsFrom October 2010 to September 2021, 74 patients who underwent cine MRI and had a definitive diagnosis of CIPO were prospectively included. We investigated disease etiology and outcomes, age at onset, nutritional status at consultation (body mass index and serum albumin), hydrogen breath test results, and total parenteral nutrition (TPN) during the disease course.ResultsForty-seven patients (64%) were women, with a mean age of 44 years at onset and 49 years at diagnosis. Primary CIPO was observed in 48 patients (65%). Secondary CIPO was observed in 26 cases (35%), of whom 18 (69%) had scleroderma. The mean body mass index, serum albumin level, and hydrogen breath test positivity rate were 17 kg/m2, 3.8 mg/dL, and 60%, respectively. TPN and invasive decompression therapy were required by 23 (31%) and 18 (24%) patients, respectively. Intestinal sterilization was performed in 51 (69%) patients and was effective in 33 (65%); of these, 28 (85%) were taking metronidazole. Seven (9%) patients used opioids. There were 9 deaths (12%), including 5 (56%) from infection and 2 (22%) from suicide. Of the deaths, 6 (67%) and 4 (44%) underwent TPN management and decompression therapy, respectively. Fifty-one patients (69%) wanted palliative care.ConclusionCIPO is a rare, severe, and under-recognized disease. Standardization of treatment strategies, including palliative care and psychiatric interventions, is desired.
| S-EPMC10334206 | biostudies-literature
Project description:BackgroundChronic intestinal pseudo-obstruction (CIPO) is a rare condition due to severe impairment of gut motility responsible for recurrent subocclusive episodes. Although neuromuscular-glial-ICC abnormalities represent the main pathogenetic mechanism, the pathophysiology of CIPO remains poorly understood. Intestinal epithelial and vascular endothelial barrier (IEVB) abnormalities can contribute to neuroepithelial changes by allowing passage of harmful substances.MethodsTo test retrospectively whether IEVB defects occur in patients with CIPO, we measured the jejunal protein expression of the major tight junction (TJ) components. CIPO patients were subdivided according to gut neuromuscular histopathology: apparently normal (AN); with inflammation (INF); or with degenerative alterations (DEG). The presence of occludin/claudin oligomers (index of TJ assembly), the amount of occludin, claudin-4, and zonula occludens-1 (ZO-1), and the expression of vasoactive intestinal polypeptide (VIP) and glial fibrillary acidic protein (GFAP) immunoreactivities were evaluated on jejunal full-thickness biopsies using Western blot.Key resultsOligomers were absent in the 73% of CIPO. Total occludin decreased in CIPO with AN and INF changes. Claudin-4 was upregulated in CIPO with INF and DEG features. ZO-1 and VIP expression decreased selectively in DEG group. GFAP increased in CIPO regardless the histopathological phenotype.Conclusions & inferencesThe absence of oligomers demonstrated in our study suggests that IEBV is altered in CIPO. The mechanism leading to oligomerization is occludin-dependent in AN and INF, whereas is ZO-1-dependent in DEG. Our study provides support to IEVB abnormalities contributing to CIPO clinical and histopathological features.
| S-EPMC6639131 | biostudies-literature
Project description:ObjectivesSSc is an autoimmune disease characterized by excessive fibrosis in multiple organs, including the gastrointestinal (GI) tract. GI symptoms of SSc such as intestinal pseudo-obstruction (IPO) are often refractory to conventional intervention and can result in longer in-hospital stay or even increased mortality. We aimed to summarize the insights to date regarding the efficacy of IVIG against GI symptoms of SSc to unveil what we should focus on in future studies.MethodsHerein we report the response of GI symptoms in three cases with SSc-myositis overlap who received IVIG administration. We also conducted a systematic literature review to summarize previous reports regarding the efficacy of IVIG upon the GI manifestations of SSc, according to the PRISMA 2020 guideline.ResultsThe case series demonstrated remarkable and rapid improvement of GI symptoms, including IPO, after IVIG administration. The literature review revealed that previous reports also support the efficacy and safety of IVIG against GI manifestations of SSc. However, they were all retrospective studies and lacking description of the short-term outcome after IVIG administration with objective and quantitative metrics.ConclusionIVIG seems to be a promising therapeutic option for the management of GI symptoms in SSc, including IPO. Investigators should focus more on short-term outcomes to properly assess the therapeutic benefit of IVIG, ideally using reliable quantitative measures in a multicentre randomized placebo-controlled setting.
| S-EPMC10473276 | biostudies-literature
Project description:Smooth Muscle Cells (SMC) are unique amongst all muscle cells in their capacity to modulate their phenotype. Indeed, SMCs do not terminally differentiate but instead harbour a remarkable capacity to dedifferentiate, switching between a quiescent contractile state and a highly proliferative and migratory phenotype, a quality often associated to SMC dysfunction. However, phenotypic plasticity remains poorly examined in the field of gastroenterology in particular in pathologies in which gut motor activity is impaired. Here, we assessed SMC status in biopsies of infants with chronic intestinal pseudo-obstruction (CIPO) syndrome, a life-threatening intestinal motility disorder. We showed that CIPO-SMCs harbour a decreased level of contractile markers. This phenotype is accompanied by an increase in Platelet-Derived Growth Factor Receptor-alpha (PDGFRA) expression. We showed that this modulation occurs without origin-related differences in CIPO circular and longitudinal-derived SMCs. As we characterized PDGFRA as a marker of digestive mesenchymal progenitors during embryogenesis, our results suggest a phenotypic switch of the CIPO-SMC towards an undifferentiated stage. The development of CIPO-SMC culture and the characterization of SMC phenotypic switch should enable us to design therapeutic approaches to promote SMC differentiation in CIPO.
| S-EPMC8051695 | biostudies-literature