Cryptogenic multifocal ulcerous stenosing enteritis (CMUSE) in a man with a diagnosis of X-linked reticulate pigmentary disorder (PDR)

Filaggrin-Associated Atopic Skin, Eye, Airways, and Gut Disease, Modifying the Presentation of X-Linked Reticular Pigmentary Disorder (XLPDR)

BACKGROUND

X-linked reticular pigmentary disorder (XLPDR) is a rare condition characterized by skin hyperpigmentation, ectodermal features, multiorgan inflammation, and recurrent infections. All probands identified to date share the same intronic hemizygous POLA1 hypomorphic variant (NM_001330360.2(POLA1):c.1393-354A > G) on the X chromosome. Previous studies have supported excessive type 1 interferon (IFN) inflammation and natural killer (NK) cell dysfunction in disease pathogenesis. Common null polymorphisms in filaggrin (FLG) gene underlie ichthyosis vulgaris and atopic predisposition.

CASE

A 9-year-old boy born to non-consanguineous parents developed eczema with reticular skin hyperpigmentation in early infancy. He suffered recurrent chest infections with chronic cough, clubbing, and asthma, moderate allergic rhinoconjunctivitis with keratitis, multiple food allergies, and vomiting with growth failure. Imaging demonstrated bronchiectasis, while gastroscopy identified chronic eosinophilic gastroduodenitis. Interestingly, growth failure and bronchiectasis improved over time without specific treatment.

METHODS

Whole-genome sequencing (WGS) using Illumina short-read sequencing was followed by both manual and orthogonal automated bioinformatic analyses for single-nucleotide variants, small insertions/deletions (indels), and larger copy number variations. NK cell cytotoxic function was assessed using 51Cr release and degranulation assays. The presence of an interferon signature was investigated using a panel of six interferon-stimulated genes (ISGs) by QPCR.

RESULTS

WGS identified a de novo hemizygous intronic variant in POLA1 (NM_001330360.2(POLA1):c.1393-354A > G) giving a diagnosis of XLPDR, as well as a heterozygous nonsense FLG variant (NM_002016.2(FLG):c.441del, NP_0020.1:p.(Arg151Glyfs*43)). Compared to healthy controls, the IFN signature was elevated although the degree moderated over time with the improvement in his chest disease. NK cell functional studies showed normal cytotoxicity and degranulation.

CONCLUSION

This patient had multiple atopic manifestations affecting eye, skin, chest, and gut, complicating the presentation of XLPDR. This highlights that common FLG polymorphisms should always be considered when assessing genotype-phenotype correlations of other genetic variation in patients with atopic symptoms. Additionally, while the patient exhibited an enhanced IFN signature, he does not have an NK cell defect, suggesting this may not be a constant feature of XLPDR.

Updates on the diagnosis and management of cryptogenic multifocal ulcerative stenosing enteropathy (CMUSE) and non-steroidal enteropathy

Crohn's disease and coeliac disease are well-known to induce ulcerations in the small-bowel. However, there is a group of very rare chronic ulcerative conditions of the small intestine that has emerged from the intestinal black box nearly 70 years ago, and that has gained interest with the advent of small-bowel capsule endoscopy and device-assisted enteroscopy. These distinct ulcerative enteropathies have come to our attention, and continue to reveal their aetiology and treatment options. Two distinct entities, called cryptogenic multifocal ulcerative stenosing enteritis/enteropathy (CMUSE) and chronic nonspecific multiple ulcers of the small intestine (CNSU) are gaining more clinical attention. CMUSE was first reported in Europe, whereas CNSU was exclusively diagnosed in Japanese patients. With the identification of susceptibility genes impacting prostaglandin metabolism, CMUSE and CNSU have become two distinct pathologies within the group of prostaglandin-associated enteropathies, to be differentiated from medication-induced enteropathies, especially non-steroidal anti-inflammatory drugs (NSAID)-induced enteropathy with similar intestinal ulcerations due to interference with prostaglandin metabolism. The current review provides an historical overview of CMUSE and CNSU publications, in addition to the currently available diagnostic and treatment options, and how to differentiate these rare enteropathies from NSAID-induced enteropathy.

DNA replication-associated inborn errors of immunity

Inborn errors of immunity are a heterogeneous group of monogenic immunologic disorders caused by mutations in genes with critical roles in the development, maintenance, or function of the immune system. The genetic basis is frequently a mutation in a gene with restricted expression and/or function in immune cells, leading to an immune disorder. Several classes of inborn errors of immunity, however, result from mutation in genes that are ubiquitously expressed. Despite the genes participating in cellular processes conserved between cell types, immune cells are disproportionally affected, leading to inborn errors of immunity. Mutations in DNA replication, DNA repair, or DNA damage response factors can result in monogenic human disease, some of which are classified as inborn errors of immunity. Genetic defects in the DNA repair machinery are a well-known cause of T^-B^-NK⁺ severe combined immunodeficiency. An emerging class of inborn errors of immunity is those caused by mutations in DNA replication factors. Considerable heterogeneity exists within the DNA replication-associated inborn errors of immunity, with diverse immunologic defects and clinical manifestations observed. These differences are suggestive for differential sensitivity of certain leukocyte subsets to deficiencies in specific DNA replication factors. Here, we provide an overview of DNA replication-associated inborn errors of immunity and discuss the emerging mechanistic insights that can explain the observed immunologic heterogeneity.

Immune Dysfunction in Mendelian Disorders of POLA1 Deficiency

POLA1 encodes the catalytic unit of DNA polymerase α, which together with the Primase complex launches the DNA replication process. While complete deficiency of this essential gene is presumed to be lethal, at least two conditions due to partial POLA1 deficiency have been described. The first genetic syndrome to be mapped to POLA1 was X-linked reticulate pigmentary disorder (XLPDR, MIM #301220), a rare syndrome characterized by skin hyperpigmentation, sterile multiorgan inflammation, recurrent infections, and distinct facial features. XLPDR has been shown to be accompanied by profound activation of type I interferon signaling, but unlike other interferonopathies, it is not associated with autoantibodies or classical autoimmunity. Rather, it is accompanied by marked Natural Killer (NK) cell dysfunction, which may explain the recurrent infections seen in this syndrome. To date, all XLPDR cases are caused by the same recurrent intronic mutation, which results in gene missplicing. Several hypomorphic mutations in POLA1, distinct from the XLPDR intronic mutation, have been recently reported and these mutations associate with a separate condition, van Esch-O'Driscoll syndrome (VEODS, MIM #301030). This condition results in growth retardation, microcephaly, hypogonadism, and in some cases, overlapping immunological features to those seen in XLPDR. This review summarizes our current understanding of the clinical manifestations of POLA1 gene mutations with an emphasis on its immunological consequences, as well as recent advances in understanding of its pathophysiologic basis and potential therapeutic options.

NK cell defects in X-linked pigmentary reticulate disorder

X-linked reticulate pigmentary disorder (XLPDR, Mendelian Inheritance in Man #301220) is a rare syndrome characterized by recurrent infections and sterile multiorgan inflammation. The syndrome is caused by an intronic mutation in POLA1, the gene encoding the catalytic subunit of DNA polymerase-α (Pol-α), which is responsible for Okazaki fragment synthesis during DNA replication. Reduced POLA1 expression in this condition triggers spontaneous type I interferon expression, which can be linked to the autoinflammatory manifestations of the disease. However, the history of recurrent infections in this syndrome is as yet unexplained. Here we report that patients with XLPDR have reduced NK cell cytotoxic activity and decreased numbers of NK cells, particularly differentiated, stage V, cells (CD3^–CD56^dim). This phenotype is reminiscent of hypomorphic mutations in MCM4, which encodes a component of the minichromosome maintenance (MCM) helicase complex that is functionally linked to Pol-α during the DNA replication process. We find that POLA1 deficiency leads to MCM4 depletion and that both can impair NK cell natural cytotoxicity and show that this is due to a defect in lytic granule polarization. Altogether, our study provides mechanistic connections between Pol-α and the MCM complex and demonstrates their relevance in NK cell function.

X-linked reticulate pigmentary disorder is associated with functional NK cell defect due to abnormal lytic granule polarization.

Cryptogenic Multifocal Ulcerating Stenosing Enteropathy(CMUSE) and/or Chronic Non-specific Multiple Ulcers of the Small Intestine(CNSU) and Non-granulomatous Ulcerating Jejunoileitis (NGUJI)

PURPOSE OF REVIEW

The purpose is to make aware of the existence of the rare and exclusive small intestine (SI) diseases, namely cryptogenic multifocal ulcerating stenosing enteropathy (CMUSE) or chronic non-specific multiple ulcers of the small intestine (CNSU) and non-granulomatous ulcerating jejunoileitis (NGUJI). The article will elucidate their epidemiology, pathogenesis, clinical features, diagnosis, differentiating features and management.

RECENT FINDINGS

Recent papers have published the clinical features and diagnostic criteria of CMUSE/CNSU and NGUJI. CNSU/CMUSE is caused by gene mutations involved in the prostaglandin pathways. Although capsule endoscopy can detect these lesions, it carries a risk of retention. TNF antagonists and azathioprine have shown response in few cases. CMUSE/CNSU and NGUJI are uncommon diseases that cause relapsing SI obstruction and bleed due to short-segment strictures and multiple shallow ulcers. This article focuses on current knowledge and novel insights regarding their pathogenesis, genetics, clinical features, diagnostic criteria and management. Multicentric clinical and genetic studies are the need of the hour.

Case report of cryptogenic multifocal ulcerous stenosing enteritis (CMUSE): a rare disease may contribute to endoscopy-capsule retention in the small intestine

Background

CMUSE is a rare disease whose diagnosis remains difficult because the lesion is confined to the small bowel.

Case presentation

Here, we present a case of 43-year-old female patient suffered chronic abdominal pain for 20 years, and finally diagnosed with CMUSE. Capsule endoscopy was performed when general endoscopic investigation failed to find the lesion, but the capsule was stranded in the small intestine. Moreover, capsule retention results in acute intestinal obstruction. Thus, surgery was performed and CMUSE was confirmed. The patient was recovered after partial small intestine resection.

Conclusions

Capsule retention occurred in nearly 60% of patients with CMUSE. Capsule endoscopy should be avoided when the patient is suspected of CMUSE, especially with severe anemia and radiologic finding in the ileum.

Case report of a pair of siblings with cryptogenic multifocal ulcerating stenosing enteritis: A rare disease easily to be misdiagnosed as Crohn disease

RATIONALE

The rare disease cryptogenic multifocal ulcerous stenosing enteritis (CMUSE) is characterized by multiple and recurring small intestinal ulcers with stenosis of unknown causes. In clinic, it is difficult to be differentiated from the inflammatory bowel disease, especially the Crohn disease.

PATIENT CONCERNS

Here we report a pair of siblings who suffered from long-time anemia and abdominal pain and misdiagnosed with inflammatory bowel disease (IBD) for many years.

DIAGNOSES

They were finally diagnosed with CMUSE with intestinal obstruction.

INTERVENTIONS AND OUTCOMES

They both accepted surgical treatment and recovered well. No abdominal symptom appeared in the two-year follow-up.

LESSONS

This report underscores that CMUSE patients may have a long course of suffering from anemia and abdominal pain, normal inflammatory markers and normal colon, and sometimes have a family history of CMUSE. Surgery of segmental bowel resection is a good way to solve intractable intestinal obstruction in CMUSE.

Cryptogenic Multifocal Ulcerous Stenosing Enteritis (CMUSE): A Tale of Three Decades

We present a patient who, over the course of 35 years, presented with repeated episodes of ileus and melena and was misdiagnosed several times, leading to several surgeries. Macroscopic and microscopic features of his resected intestine were compatible with cryptogenic multifocal ulcerous stenosis enteritis (CMUSE), but additional angioectatic lesions were also noted. The patient responded dramatically to hormonal therapy consisting of ethinylestradiol and norethisterone. To our knowledge, this is the first reported case of CMUSE that has shown response to hormonal therapy. We suggest that this is a variant of CMUSE in which vasculopathy plays a role in the pathogenesis.

Severe Cryptogenic Multifocal Ulcerous Stenosing Enteritis. A Report of Three Cases and Review of the Literature

Cryptogenic multifocal ulcerous stenosing enteritis (CMUSE) is a rare condition characterised by chronic or relapsing moderate ileous episodes resulting from multiple small intestinal strictures, multiple shallow ulcers of the small bowel and favourable therapeutical effect of glucocorticosteroids. The aim of this paper was to evaluate three cases of CMUSE diagnosed within 10 years at a tertiary gastroenterology centre. Three females (35, 50, 60 years) were presented with colicky pain, repeated moderate ileous episodes and weight loss. Multiple fibrous strictures and ulcers of the small bowel were found. All three patients responded to glucocorticosteroid treatment. Tandem tight jejunal stenoses were dilated endoscopically by means of double balloon enteroscopy. In conclusion, CMUSE should always be considered when chronic moderate ileous episodes and multiple small intestinal strictures and ulcers of uncertain aetiology are found. Double balloon enteroscopy enables precise diagnostic work, possible endoscopic treatment of stenoses, may obviate the need for surgery and prevent excessive small bowel resections.

DNA polymerase-α regulates the activation of type I interferons through cytosolic RNA:DNA synthesis

Aberrant nucleic acids generated during viral replication are the main trigger for antiviral immunity, and mutations that disrupt nucleic acid metabolism can lead to autoinflammatory disorders. Here we investigated the etiology of X-linked reticulate pigmentary disorder (XLPDR), a primary immunodeficiency with autoinflammatory features. We discovered that XLPDR is caused by an intronic mutation that disrupts the expression of POLA1, which encodes the catalytic subunit of DNA polymerase-α. Unexpectedly, POLA1 deficiency resulted in increased production of type I interferons. This enzyme is necessary for the synthesis of RNA:DNA primers during DNA replication and, strikingly, we found that POLA1 is also required for the synthesis of cytosolic RNA:DNA, which directly modulates interferon activation. Together this work identifies POLA1 as a critical regulator of the type I interferon response.

Cryptogenic multifocal ulcerous stenosing enteritis: a review of the literature

Cryptogenic multifocal ulcerous stenosing enteritis (CMUSE) is an extremely rare illness characterised by chronic or relapsing subileus status resulting from multiple small intestinal fibrous strictures and multiple shallow ulcers of the small bowel. The etiology is unknown and pathogenesis is not fully understood. Therapy with systemic glucocorticosteroids is the treatment of choice. However, most patients develop corticosteroid dependence. Deep enteroscopy enables precise diagnostic work, possible endoscopic treatment of stenoses; may obviate the need for surgery and prevent excessive small bowel resections.

Cryptogenia multifocal ulcerous stenosing enteritis: an entity on its own as a cause of abdominal pain, iron deficiency anemia and protein-losing enteropathy

We studied a patient with edema secondary to protein losing enteropathy, and recurrent bouts of bloating and abdominal pain secondary to intestinal subocclusion episodes. After the clinical study, the patient was diagnosed of cryptogenic multifocal ulcerous stenosing enteritis (CMUSE), that is a rare disease, probably caused by mutations in the gene PLA2G4A, and characterized by multiple short stenosis of the small bowel with superficial ulcers, which do not exceed the submucosa layer. Inflammatory bowel disease (Chron's disease), intestinal tuberculosis and intestinal ulcers secondary to non-steroidal anti-inflammatory drugs are the main differential diagnosis. To sum up, physicians should included CMUSE in the differential diagnosis of recurrent abdominal pain, iron deficiency anaemia, occult intestinal bleeding, edema and protein losing enteropathy.

X-linked reticulate pigmentary disorder with systemic manifestations: a new family and review of the literature

X-linked reticulate pigmentation disorder with systemic manifestations (XLPDR) is an extremely rare genodermatosis with recessive X-linked inheritance but unknown molecular basis. In males, cutaneous involvement is characterized by reticulate hyperpigmentation of the skin that is associated with a typical facies and severe systemic involvement. In the carrier females, manifestations are apparently limited to the skin with patchy linear hyperpigmentation following the lines of Blaschko that are similar to stage III incontinentia pigmenti. Thus far, only five families affected by this disorder have been described. We report on a new family with clinical features of XLPDR and compare it with those reported in the literature.

Cryptogenic multifocal ulcerous stenosing enteritis: A report of one case and review of the literature

Cryptogenic multifocal ulcerous stenosing enteritis (CMUSE) is a rare condition characterized by chronic or relapsing moderate ileus episodes resulting from multiple small intestinal strictures, multiple superficial ulcers of the small bowel and favorable therapeutic effect of glucocorticosteroids. Here we report a case of CMUSE in a 77-year-old female who presented with colicky pain, repeated moderate ileus episodes and weight loss. Multiple fibrous strictures and ulcers of the small bowel were found. The patient responded to glucocorticosteroid treatment. Severe tandem tight jejunal stenosis may be dilated endoscopically by means of double balloon enteroscopy. CMUSE should be considered when chronic moderate ileus episodes and multiple small intestinal strictures and ulcers of uncertain etiology are found. Double balloon enteroscopy enables precise diagnostic work, possible endoscopic treatment of stenosis, and may obviate the need for surgery and prevent excessive small bowel resections.