Rotor Syndrome Presenting as Dubin-Johnson Syndrome

A 42-year-old man with no relevant past medical history presented with intermittent mild icterus and no signs of chronic liver disease. Laboratory tests were notable for hyperbilirubinemia (total 7.97 mg/dL, direct 5.37 mg/dL), bilirubinuria, no signs of hemolysis, normal liver tests and lipids profile. Abdominal ultrasound was unremarkable. A panel of chronic liver diseases was negative except for increased serum (147.4 μg/dL) and urinary (179 μg/24 h) copper, with normal ceruloplasmin. No other Leipzig criteria for Wilson’s disease were found, including a negative test for ATP7B gene mutations (by exome sequencing). Total urinary coproporphyrin was normal with predominance of isomer I (86% of total urinary coproporphyrin output). Clinical and laboratorial profile was compatible with Dubin-Johnson syndrome; however, exome sequencing and search for deletions in the ABBC2 gene (encoding MRP2) only found a heterozygous potentially pathogenic variant (c.1483A>G – p.Lys495Glu). Additional extended molecular analysis of genes implicated in bilirubin metabolism found a homozygous deletion of a region encompassing exons 4–16 of SLCO1B3 gene (encoding OATP1B3) and all SLCO1B1 exons (encoding OATP1B1), thereby establishing Rotor syndrome diagnosis. Rotor and DubinJohnson syndromes are rare autosomal recessive liver diseases characterized by chronic conjugated hyperbilirubinemia, caused by the absence of the hepatic function OATP1B1/B3 (leading to impaired hepatic bilirubin reuptake and storage) and MRP2 transporters (leading to impaired hepatic bilirubin excretion), respectively. We report a case of compound hereditary hyperbilirubinemia with a misleading presentation with special focus on its diagnosis, particularly the advantage of extensive unbiased genetic testing by dedicated laboratories. With this case, we aim to highlight the necessity of establishing a diagnosis, reassuring the patient, and avoiding unnecessary invasive and costly diagnostic procedures.info:eu-repo/semantics/publishedVersio

Involvement of the Modifier Gene of a Human Mendelian Disorder in a Negative Selection Process

BACKGROUND:Identification of modifier genes and characterization of their effects represent major challenges in human genetics. SAA1 is one of the few modifiers identified in humans: this gene influences the risk of renal amyloidosis (RA) in patients with familial Mediterranean fever (FMF), a Mendelian autoinflammatory disorder associated with mutations in MEFV. Indeed, the SAA1 alpha homozygous genotype and the p.Met694Val homozygous genotype at the MEFV locus are two main risk factors for RA. METHODOLOGY/PRINCIPAL FINDINGS:HERE, WE INVESTIGATED ARMENIAN FMF PATIENTS AND CONTROLS FROM TWO NEIGHBORING COUNTRIES: Armenia, where RA is frequent (24%), and Karabakh, where RA is rare (2.5%). Sequencing of MEFV revealed similar frequencies of p.Met694Val homozygotes in the two groups of patients. However, a major deficit of SAA1 alpha homozygotes was found among Karabakhian patients (4%) as compared to Armenian patients (24%) (p = 5.10(-5)). Most importantly, we observed deviations from Hardy-Weinberg equilibrium (HWE) in the two groups of patients, and unexpectedly, in opposite directions, whereas, in the two control populations, genotype distributions at this locus were similar and complied with (HWE). CONCLUSIONS/SIGNIFICANCE:The excess of SAA1alpha homozygotes among Armenian patients could be explained by the recruitment of patients with severe phenotypes. In contrast, a population-based study revealed that the deficit of alpha/alpha among Karabakhian patients would result from a negative selection against carriers of this genotype. This study, which provides new insights into the role of SAA1 in the pathophysiology of FMF, represents the first example of deviations from HWE and selection involving the modifier gene of a Mendelian disorder

The Multifaceted Role of Epoxide Hydrolases in Human Health and Disease

International audienceEpoxide hydrolases (EHs) are key enzymes involved in the detoxification of xenobiotics and biotransformation of endogenous epoxides. They catalyze the hydrolysis of highly reactive epoxides to less reactive diols. EHs thereby orchestrate crucial signaling pathways for cell homeostasis. The EH family comprises 5 proteins and 2 candidate members, for which the corresponding genes are not yet identified. Although the first EHs were identified more than 30 years ago, the full spectrum of their substrates and associated biological functions remain partly unknown. The two best-known EHs are EPHX1 and EPHX2. Their wide expression pattern and multiple functions led to the development of specific inhibitors. This review summarizes the most important points regarding the current knowledge on this protein family and highlights the particularities of each EH. These different enzymes can be distinguished by their expression pattern, spectrum of associated substrates, sub-cellular localization, and enzymatic characteristics. We also reevaluated the pathogenicity of previously reported variants in genes that encode EHs and are involved in multiple disorders, in light of large datasets that were made available due to the broad development of next generation sequencing. Although association studies underline the pleiotropic and crucial role of EHs, no data on high-effect variants are confirmed to date

Editorial: Endocrine and metabolic diseases – genetic impact and therapies

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Familial Mediterranean Fever in Heterozygotes: Are We Able to Accurately Diagnose the Disease in Very Young Children?

International audienceObjective: Familial Mediterranean fever (FMF) is an autosomal-recessive autoinflammatory disease due to mutations in MEFV. Descriptions of disease manifestations among patients carrying a single mutated MEFV allele are becoming more frequent, although no data are available on the long-term outcome. We undertook this study to assess the accuracy of clinical diagnosis in children carrying a single mutated MEFV allele with symptoms of recurrent autoinflammatory disorder.Methods: We performed a retrospective single-center study of 33 patients with autoinflammatory disorders age <6 years at disease onset with 1 mutated MEFV allele. The phenotype of the patients was investigated in detail, and the clinical picture and outcome of 18 patients with an initial FMF diagnosis according to current clinical criteria were compared to those of 25 homozygous or compound heterozygous FMF patients.Results: No major differences in presenting signs or initial response to colchicine were observed between patient groups. During followup, heterozygotes had a milder disease course compared to homozygotes and were less prone than homozygotes to experience new clinical signs of FMF. At puberty, clinical signs of FMF completely disappeared in 5 of 18 heterozygotes, allowing them to discontinue colchicine without recurrence of symptoms or increases in inflammatory marker levels.Conclusion: Our data suggest that the clinical diagnosis of FMF in very young heterozygous children should be made with caution. At this young age they can present with an FMF-like disease-similar to that seen in patients carrying 2 mutated alleles-that is not necessarily predictive of life-long illness

PW03-034 - How to classify autoinflammatory diseases?

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Two Decades after Mandibuloacral Dysplasia Discovery: Additional Cases and Comprehensive View of Disease Characteristics

International audiencePathogenic variants in the LMNA gene cause a group of heterogeneous genetic disorders, called laminopathies. In particular, homozygous or compound heterozygous variants in LMNA have been associated with “mandibuloacral dysplasia type A” (MADA), an autosomal recessive disorder, characterized by mandibular hypoplasia, growth retardation mainly postnatal, pigmentary skin changes, progressive osteolysis of the distal phalanges and/or clavicles, and partial lipodystrophy. The detailed characteristics of this multisystemic disease have yet to be specified due to its rarity and the limited number of cases described. Here, we report three unrelated Egyptian patients with variable severity of MAD features. Next-generation sequencing using a gene panel revealed a homozygous c.1580G>A-p.Arg527His missense variant in LMNA exon 9 in an affected individual with a typical MADA phenotype. Another homozygous c.1580G>T-p.Arg527Leu variant affecting the same amino acid was identified in two additional patients, who both presented with severe manifestations very early in life. We combined our observations together with data from all MADA cases reported in the literature to get a clearer picture of the phenotypic variability in this disease. This work raises the number of reported MADA families, argues for the presence of the founder effect in Egypt, and strengthens genotype–phenotype correlations

How should we approach classification of autoinflammatory diseases?

International audienceThe notion of 'autoinflammatory' disease was introduced at the end of the 1990s, and, since then, this concept has rapidly evolved. As a result, multiple definitions of autoinflammatory disease, and classifications of conditions encompassed by these definitions, have been proposed; this succession highlights advances that have been made in understanding of the innate immune system, and especially the roles of IL-1β and the inflammasome in autoinflammtory conditions. However, the definitions and classifications that have been suggested to date face a number of structure and content issues. We therefore propose another, more clinically-oriented, definition: autoinflammatory diseases are diseases with clinical signs of inflammation, associated with elevated levels of acute-phase reactants, which are attributable to dysfunction of the innate immune system, genetically-determined or triggered by an endogenous factor. From this foundation, we propose a clinically-based classification of autoinflammatory diseases, and go on to discuss how immunological diseases as a whole, including autoimmune diseases, can be appropriately located within a continuum only if the classification process is multidimensional. For this purpose, we appeal to the philosophical concepts of family resemblance and signature

Cardiovascular complications of lipodystrophic syndromes – focus on laminopathies

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Lipodystrophic syndromes: From diagnosis to treatment

International audienceLipodystrophic syndromes are acquired or genetic rare diseases, characterised by a generalised or partial lack of adipose tissue leading to metabolic alterations linked to strong insulin resistance. They encompass a variety of clinical entities due to primary defects in adipose differentiation, in the structure and/or regulation of the adipocyte lipid droplet, or due to immune-inflammatory aggressions, chromatin deregulations and/or mitochondrial dysfunctions affecting adipose tissue. Diagnosis is based on clinical examination, pathological context and comorbidities, and on results of metabolic investigations and genetic analyses, which together determine management and genetic counselling. Early lifestyle and dietary measures focusing on regular physical activity and avoiding excess energy intake are crucial. They are accompanied by multidisciplinary follow-up adapted to each clinical form. In case of hyperglycemia, antidiabetic medications, with metformin as a first-line therapy in adults, are used in addition to lifestyle and dietary modifications. When standard treatments have failed to control metabolic disorders, the orphan drug metreleptin, an analog of leptin, can be effective in certain forms of lipodystrophy syndrome. Metreleptin therapy indications, prescription and monitoring were recently defined in France, representing a major improvement in patient care