The spectrum of clinical presentation in haploinsufficiency of A20; a case report of a novel mutation in TNFAIP3 gene

Haploinsufficiency of A20 was first described in 2016 as a new autoinflammatory disease that clinically presents as early-onset Behcet's disease. After the publication of the first 16 cases, more patients were diagnosed and described in the literature. The spectrum of clinical presentation has expanded. In this short report, we present a patient with a novel mutation in the TNFAIP3 gene. The clinical presentation included signs of an autoinflammatory disease with recurrent fever, abdominal pain, diarrhea, respiratory tract infections, and elevated inflammatory parameters. We will emphasize the importance of genetic testing, especially in patients with various clinical signs that do not fit a single autoinflammatory disease.

THU0019 INTRON REGIONS OF PIK3AP1 (BCAP) AND SPON2 (SPONDIN-2) GENES ARE DIFFERENTIALLY METHYLATED IN PATIENTS WITH PERIODIC FEVER, APHTHOUS STOMATITIS, PHARYNGITIS AND ADENITIS (PFAPA) SYNDROME

Background:

Periodic fever, aphthous stomatitis, pharyngitis and adenitis (PFAPA) syndrome is the most common autoinflammatory disease in children, often grouped together with hereditary periodic fever syndromes, although its cause and hereditary nature remain unexplained.

Objectives:

We investigated whether a differential DNA methylation was present in DNA from peripheral blood mononuclear cells (PBMC) in patients with PFAPA versus a group of healthy young individuals.

Methods:

A whole epigenome analysis (MeDIP and MBD) was performed using pooled DNA libraries enriched for methylated genomic regions. Of identified candidate genes, two with most significantly different methylation leves were further evaluated with methylation specific restriction enzymes coupled with qPCR (MSRE-qPCR).

Results:

The analysis showed thatPIK3AP1andSPON2intronic gene regions are differentially methylated in patients with PFAPA. MSRE-qPCR proved as a quick, reliable and cost-effective method to confirm results from MeDIP and MBD.

Conclusion:

Our findings indicate that B cell adapter protein (BCAP) as PI3K binding inhibitor of inflammation and spondin-2 (SPON2) as a pattern recognition molecule and integrin ligand could play a role in etiology of PFAPA. Their role and impact of changed DNA methylation in PFAPA etiology and autoinflammation need further investigation.

References:

[1]Wekell P. Periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis syndrome – PFAPA syndrome. Press Medicale [Internet]. 2019;48(1):e77–87. Available from:https://doi.org/10.1016/j.lpm.2018.08.016

[2]K. Theodoropoulou, F. Vanoni, and M. Hofer, “Periodic Fever, Aphthous Stomatitis, Pharyngitis, and Cervical Adenitis (PFAPA) Syndrome: a Review of the Pathogenesis,”Curr. Rheumatol. Rep., vol. 18:18, 2016.

[3]Carpentier SJ, Ni M, Duggan JM, James RG, Cookson BT, Hamerman JA. The signaling adaptor BCAP inhibits NLRP3 and NLRC4 inflammasome activation in macrophages through interactions with Flightless-1. Sci Signal. 2019;12(581).

[4]He YW, Li H, Zhang J, Hsu CL, Lin E, Zhang N, et al. The extracellular matrix protein mindin is a pattern-recognition molecule for microbial pathogens. Nat Immunol. 2004;5(1):88–97.

Disclosure of Interests:

None declared

High frequency of pathogenic ACAN variants including an intragenic deletion in selected individuals with short stature

CONTEXT

Defining the underlying etiology of idiopathic short stature (ISS) improves the overall management of an individual.

OBJECTIVE

To assess the frequency of pathogenic ACAN variants in selected individuals.

DESIGN

The single-center cohort study was conducted at a tertiary university children's hospital. From 51 unrelated patients with ISS, the 16 probands aged between 3 and 18 years (12 females) with advanced bone age and/or autosomal dominant inheritance pattern of short stature were selected for the study. Fifteen family members of ACAN-positive probands were included. Exome sequencing was performed in all probands, and additional copy number variation (CNV) detection was applied in selected probands with a distinct ACAN-associated phenotype.

RESULTS

Systematic phenotyping of the study cohort yielded 37.5% (6/16) ACAN-positive probands, with all novel pathogenic variants, including a 6.082 kb large intragenic deletion, detected by array comparative genomic hybridization (array CGH) and exome data analysis. All variants were co-segregated with short stature phenotype, except in one family member with the intragenic deletion who had an unexpected growth pattern within the normal range (-0.5 SDS). One patient presented with otosclerosis, a sign not previously associated with aggrecanopathy.

CONCLUSIONS

ACAN pathogenic variants presented a common cause of familial ISS. The selection criteria used in our study were suggested for a personalized approach to genetic testing of the ACAN gene in clinical practice. Our results expanded the number of pathogenic ACAN variants, including the first intragenic deletion, and suggested CNV evaluation in patients with typical clinical features of aggrecanopathy as reasonable. Intra-familial phenotypic variability in growth patterns should be considered.

Functional analysis of the bovine beta- and kappa casein gene promoters using homologous mammary gland derived cell line

Abstract. Bovine casein gene cluster belongs to the best studied regions of the bovine genome. However, molecular basis of the regulation of casein gene expression is still of great interest for the advancement of milk production. Identification of crucial regulatory regions governing casein gene expression would provide valuable information for marker assisted selection in dairy cattle. In our study we performed comparative analysis of the bovine beta- and kappa casein gene promoter sequences with the regulatory sequences from some other species. In addition, we used homologous mammary gland derived cell culture and luciferase reporter gene system to confirm the functionality of the proximal beta and kappa casein promoters. The longer kappa casein promoter (2064 bp) showed the highest expression level, followed by the short kappa casein promoter (925 bp) and beta casein promoter (1692 bp). Here we demonstrate the suitability of the bovine mammary gland derived cell line BME UV1 for transient gene expression under transcriptional control of the bovine casein gene promoters and compare functionality of different fragments of bovine beta- and kappa casein gene promoters using homologous in vitro system.

Allelic differences in bovine kappa-CN gene which may regulate gene expression

The most common kappa casein (kappa-CN) variants, kappa-CN A and kappa-CN B, are synthesised differentially in the lactating mammary gland of heterozygous animals (kappa-CN AB). In this study we evaluated several approaches for quantification of allele specific mRNA transcripts. The most consistent results were obtained using allele specific RT-PCR and capillary electrophoresis. On average, 13.4% more allele B specific than A specific transcripts were found. DNA sequencing of the proximal promoter region in several homozygous animals (kappa-CN AA, BB, EE) did not reveal any allele specific polymorphisms. Using the EMSA and DNase I footprinting we confirmed functional binding sites for three transcription factors (AP-2, NF1 and MGF) within the kappa-CN proximal promoter region. Sequence analysis of the 3'-UTR of the kappa-CN gene revealed seven allele specific sites. Two of these allelic differences were close to previously identified 3'-end regulatory sequences. In addition, allele specific differences in length between mRNAs of both variants were found. The two later findings suggest a possible post translational control determining content differences of kappa-CN in milk.

Molecular evidence for nosocomial spread of two different hepatitis C virus strains in one hemodialysis unit

The highest prevalence of hepatitis C virus (HCV) infection among hemodialysis patients in Slovenia was found in a small dialysis unit with old equipment and room shortage, where the first anti-HCV-positive patient was detected in 1990. In 1992 and 1993, an additional 8 and 7 patients seroconverted, respectively. Genotyping analyses among 15 HCV RNA-positive patients showed quite unusual HCV genotype distribution for our country: genotypes 2 and 3 were determined in 9 and 6 patients, respectively. Sequence analysis of the 270-bp part of the NS-5 region was carried out in 12 patients. In 6 patients infected with subtype 2c and in 4 patients infected with subtype 3a, very similar sequences were obtained, forming two distinct clusters in the phylogenetic tree. In 2 patients infected with subtype 2c, viral strains were neither related to the main 2c strain nor to each other. Phylogenetic analysis unequivocally confirmed simultaneous nosocomial spread of two different HCV strains in one hemodialysis unit. The study confirmed that implementation of rigorous hygienic routines and introduction of separate rooms and machines for HCV-infected patients are important measures for effective control of HCV infection in a hemodialysis environment.