Desquamative enteropathy and pyloric atresia without skin disease caused by a novel intracellular beta4 integrin mutation

Breaking Down Barriers: Epithelial Contributors to Monogenic IBD Pathogenesis

Monogenic causes of inflammatory bowel diseases (IBD) are increasingly being discovered. To date, much attention has been placed in those resulting from inborn errors of immunity. Therapeutic efforts have been largely focused on offering personalized immune modulation or curative bone marrow transplant for patients with IBD and underlying immune disorders. To date, less emphasis has been placed on monogenic causes of IBD that pertain to impairment of the intestinal epithelial barrier. Here, we provide a comprehensive review of monogenic causes of IBD that result in impaired intestinal epithelial barrier that are categorized into 6 important functions: (1) epithelial cell organization, (2) epithelial cell intrinsic functions, (3) epithelial cell apoptosis and necroptosis, (4) complement activation, (5) epithelial cell signaling, and (6) control of RNA degradation products. We illustrate how impairment of any of these categories can result in IBD. This work reviews the current understanding of the genes involved in maintaining the intestinal barrier, the inheritance patterns that result in dysfunction, features of IBD resulting from these disorders, and pertinent translational work in this field.

ITGB4-mutated Junctional Epidermolysis Bullosa without Pyloric Atresia Presenting with Severe Urinary Involvement and Late-onset Minimal Skin Fragility: Diagnostic and Therapeutic Challenges

Abstract is missing (Short communication)

Biallelic ITGB4 variants in familial pyloric atresia without epidermolysis bullosa: Report of two families with five siblings

Pyloric atresia (PA) is a rare gastrointestinal anomaly that occurs either as an isolated lesion or in association with other congenital or hereditary anomalies. Familial occurrence of PA with epidermolysis bullosa (EB) has been well documented and variants in ITGA6, ITGB4, and PLEC are known to cause EB with PA. However, no gene variants have been defined in familial isolated PA. Five siblings with familial isolated PA are presented that suggest biallelic ITGB4 variants may underlie the development of PA without EB. Five siblings from two unrelated families with isolated PA were studied with exome sequencing (ES) to identify the genetic etiology in isolated familial cases. Exome sequencing was performed in one affected patient from each family. Validation and segregation studies were done by Sanger sequencing. Parents were first cousins in one family but there was no consanguinity in the other family. Type-2 PA was detected in both families and none of the probands had associated anomalies. All patients underwent successful gastroduodenostomy and have been under follow-up uneventfully. All patients had biallelic ITGB4 variants, c.2032G > T p.(Asp678Tyr) being a novel one. Biallelic ITGB4 variants may underlie the development of PA without associated EB. Further detection of variants in this gene may establish any possible genotype-phenotype correlations.

Epidermolysis bullosa with pyloric atresia associated with compound heterozygous ITGB4 pathogenic variants: Minimal skin involvement but severe mucocutaneous disease

We report a case of junctional epidermolysis bullosa with pyloric atresia (JEB-PA) with minimal skin involvement but severe protein-losing enteropathy and airway involvement. Genetic analysis revealed heterozygous mutations in the ITGB4 gene encoding integrin β4 protein. Parental testing confirmed inheritance of frameshift variant (c.794dupC) as maternal and splice site variant (c.1608C>T/p.Cys536Cys) as paternal. Immunofluorescence mapping of her skin revealed a subepidermal blister with decreased and frayed integrin β4 at both the floor and the roof of the blister, while the intestinal mucosa showed complete absence of integrin β4. We review the literature and discuss the differential expression of integrins in the skin and gastrointestinal tract, as well as the role of chronic inflammation in the pathogenesis of EB.

Über die Problematik der klinischen Entscheidungsfindung aufgrund von Fallbeschreibungen – ethische Implikationen am Beispiel eines Falls von Carmi Syndrom

Bei extrem seltenen Erkrankungen bilden Fallbeschreibungen oft die einzige Datengrundlage für klinische Entscheidungen. Das Carmi Syndrom ist eine seltene Kombination von Epidermolysis bullosa und Pylorusatresie. Während der Betreuung einer betroffenen Patientin fielen unterschiedliche Wahrnehmungen über die publizierten Mortalitätsraten auf. Daraufhin wurde die Hypothese untersucht, ob sich die kumulativen Mortalitätsraten von Einzelfallbeschreibungen und Mehrfachfallbeschreibungen unterscheiden, um so eine mögliche Verzerrung der Prognose in ihren Auswirkungen auf klinische und ethische Einschätzungen des Falls zu überprüfen.

Ein Mädchen wurde in der Schwangerschaftswoche 33 mit Carmi Syndrom geboren. Zusammen mit dem klinischen Ethikkomitee wurden Behandlungsoptionen diskutiert, einschließlich einer palliativen Behandlung oder einer operativen Gastrojejunostomie. Da etwa ein Drittel der in Fallbeschreibungen publizierten Kinder nach einer Operation überlebten, entschieden wir uns auch vor dem Hintergrund unsicherer Prognosen für das chirurgische Vorgehen. Die Patientin starb 4 Wochen später nach multiplen Komplikationen.

Die Datenbank PubMed wurde nach Publikationen über Carmi Syndrom durchsucht. Das Outcome von Einzelfallbeschreibungen wurde mit dem von Mehrfachfallbeschreibungen verglichen.

Insgesamt wurden 102 Fälle von Carmi Syndrom identifiziert. Die Mortalität bei Einzelfallbeschreibungen belief sich auf 17 von 27 Fällen (63 %), während 62 von 74 Patienten von Mehrfachfallbeschreibungen starben (84 %, p = 0,036).

Beim Carmi Syndrom unterscheidet sich die publizierte Mortalität zwischen Einfach- und Mehrfachfallbeschreibungen, möglicherweise aufgrund einer Kombination von Selektions- und Publikationsbias. Die Unterschätzung der tatsächlichen Mortalitätsrate kann zu unangebracht intensiven Therapieansätzen führen. Kliniker und Ethiker sollten daher vorsichtig sein, ihre Entscheidungen bei seltenen oder neuartigen Erkrankungen auf kumulative Erfahrungen von Fallbeschreibungen, insbesondere von Einzelfallbeschreibungen, zu basieren, die positive Verläufe von Behandlungen zu betonen scheinen.

Clinical subtypes and molecular basis of epidermolysis bullosa in Kuwait

BACKGROUND

Epidermolysis bullosa (EB) is a clinically and genetically heterogeneous blistering skin disease, but in countries such as Kuwait, there are very limited data on the clinical and molecular pathology of EB. To improve understanding of EB in Kuwait, we report the experience of a local tertiary referral center over a 17.5 year period (January 2000-June 2017) in establishing clinical and molecular diagnoses.

METHODS

Review of hospital records and diagnostic reports. Individual cases were diagnosed by combinations of clinical assessment, skin biopsy (immunohistochemistry and transmission electron microscopy), Sanger sequencing of EB genes, and whole exome sequencing.

RESULTS

Fifty-four families with EB were registered with the clinic over this period, 41 of whom (84 patients) participated in diagnostic studies. Thirty-seven of these 41 families had consanguineous marriages; 34 had recessive forms of EB, while only seven had dominant subtypes. Recurrent mutations were observed in epidermal dystonin, transglutaminase 5, and type VII collagen.

CONCLUSIONS

The prevalence of EB in Kuwait is approximately three times that of internationally cited rates with an over-representation of autosomal recessive variants. Establishing the molecular basis of EB in Kuwait with accurate diagnostic subtyping provides a basis for determining healthcare requirements and improving patient management of EB.

Phenotypic spectrum of epidermolysis bullosa associated with α6β4 integrin mutations

BACKGROUND

Integrin α6β4 is a transmembrane receptor and a key component of the hemidesmosome anchoring complex. It is involved in cell-matrix adhesion and signalling in various tissues. Mutations in the ITGA6 and ITGB4 genes coding for α6β4 integrin compromise dermal-epidermal adhesion and are associated with skin blistering and pyloric atresia (PA), a disorder known as epidermolysis bullosa with PA (EB-PA).

OBJECTIVES

To elucidate the molecular pathology of skin fragility in eight cases, disclose the underlying ITGA6 and ITGB4 mutations and study genotype-phenotype correlations.

METHODS

DNA was isolated from ethylenediaminetetraacetic acid-blood samples, and the coding exons and exon-intron boundaries of ITGA6 and ITGB4 were amplified by polymerase chain reaction (PCR), and directly sequenced. Skin samples were submitted to immunofluorescence mapping with antibodies to adhesion proteins of the dermal-epidermal junction. Primary keratinocytes were isolated, and used for RNA and protein extraction, reverse transcription PCR and immunoblotting. Ultrastructural analysis of the skin was performed in one patient.

RESULTS

We disclose 10 novel mutations, one in ITGA6 and nine in ITGB4. Skin cleavage was either intraepidermal or junctional. Lethal outcome and PA correlated with loss-of-function mutations in two cases. Solely mild skin involvement was associated with deletion of the C-terminus of β4 integrin. Combinations of missense, nonsense or frameshift mutations caused severe urinary tract involvement in addition to skin fragility in five cases.

CONCLUSIONS

The present study reveals novel ITGA6 and ITGB4 gene mutations and supports previous reports showing that the phenotype may lack PA and be limited to skin and nail involvement. In four out of six cases of EB-PA, life expectancy was not impaired. A high frequency of urinary tract involvement was found in this study, and represented the main cause of morbidity. Low levels of β4 integrin expression were compatible with hemidesmosomal integrity and a mild skin phenotype.

Epidermolysis bullosa with pyloric atresia

Epidermolysis bullosa (EB) with pyloric atresia (PA) is a rare form of EB. This article describes the clinical and pathologic features and molecular genetics of EB-PA, the mutations in the alpha(6)beta(4) integrin and plectin genes that cause EB-PA, and the clinical implications of molecular genetics on EB-PA.