ADH1B, the adipocyte-enriched alcohol dehydrogenase, plays an essential, cell-autonomous role in human adipogenesis.

Alcohol dehydrogenase 1B (ADH1B) is a primate-specific enzyme which, uniquely among the ADH class 1 family, is highly expressed both in adipose tissue and liver. Its expression in adipose tissue is reduced in obesity and increased by insulin stimulation. Interference with ADH1B expression has also been reported to impair adipocyte function. To better understand the role of ADH1B in adipocytes, we used CRISPR/Cas9 to delete ADH1B in human adipose stem cells (ASC). Cells lacking ADH1B failed to differentiate into mature adipocytes manifested by minimal triglyceride accumulation and a marked reduction in expression of established adipocyte markers. As ADH1B is capable of converting retinol to retinoic acid (RA), we conducted rescue experiments. Incubation of ADH1B-deficient preadipocytes with 9-cis-RA, but not with all-transretinol, significantly rescued their ability to accumulate lipids and express markers of adipocyte differentiation. A homozygous missense variant in ADH1B (p.Arg313Cys) was found in a patient with congenital lipodystrophy of unknown cause. This variant significantly impaired the protein's dimerization, enzymatic activity, and its ability to rescue differentiation in ADH1B-deficient ASC. The allele frequency of this variant in the Middle Eastern population suggests that it is unlikely to be a fully penetrant cause of severe lipodystrophy. In conclusion, ADH1B appears to play an unexpected, crucial and cell-autonomous role in human adipocyte differentiation by serving as a necessary source of endogenous retinoic acid.

RIPK3 dampens mitochondrial bioenergetics and lipid droplet dynamics in metabolic liver disease.

BACKGROUND AND AIMS: Receptor-interacting protein kinase 3 (RIPK3) mediates NAFLD progression, but its metabolic function is unclear. Here, we aimed to investigate the role of RIPK3 in modulating mitochondria function, coupled with lipid droplet (LD) architecture in NAFLD. APPROACH AND RESULTS: Functional studies evaluating mitochondria and LD biology were performed in wild-type (WT) and Ripk3-/- mice fed a choline-deficient, amino acid-defined (CDAA) diet for 32 and 66 weeks and in CRISPR-Cas9 Ripk3 -null fat-loaded immortalized hepatocytes. The association between hepatic perilipin (PLIN) 1 and 5, RIPK3, and disease severity was also addressed in a cohort of patients with NAFLD and in PLIN1 -associated familial partial lipodystrophy. Ripk3 deficiency rescued impairment in mitochondrial biogenesis, bioenergetics, and function in CDAA diet-fed mice and fat-loaded hepatocytes. Ripk3 deficiency was accompanied by a strong upregulation of antioxidant systems, leading to diminished oxidative stress upon fat loading both in vivo and in vitro. Strikingly, Ripk3-/- hepatocytes displayed smaller size LD in higher numbers than WT cells after incubation with free fatty acids. Ripk3 deficiency upregulated adipocyte and hepatic levels of LD-associated proteins PLIN1 and PLIN5. PLIN1 upregulation controlled LD structure and diminished mitochondrial stress upon free fatty acid overload in Ripk3-/- hepatocytes and was associated with diminished human NAFLD severity. Conversely, a pathogenic PLIN1 frameshift variant was associated with NAFLD and fibrosis, as well as with increased hepatic RIPK3 levels in familial partial lipodystrophy. CONCLUSIONS: Ripk3 deficiency restores mitochondria bioenergetics and impacts LD dynamics. RIPK3 inhibition is promising in ameliorating NAFLD.

Clinical features of generalized lipodystrophy in Turkey: A cohort analysis.

AIM: To describe the Turkish generalized lipodystrophy (GL) cohort with the frequency of each complication and the death rate during the period of the follow-up. METHODS: This study reports on 72 patients with GL (47 families) registered at different centres in Turkey that cover all regions of the country. The mean ± SD follow-up was 86 ± 78 months. RESULTS: The Kaplan-Meier estimate of the median time to diagnosis of diabetes and/or prediabetes was 16 years. Hyperglycaemia was not controlled in 37 of 45 patients (82.2%) with diabetes. Hypertriglyceridaemia developed in 65 patients (90.3%). The Kaplan-Meier estimate of the median time to diagnosis of hypertriglyceridaemia was 14 years. Hypertriglyceridaemia was severe (≥ 500 mg/dl) in 38 patients (52.8%). Seven (9.7%) patients suffered from pancreatitis. The Kaplan-Meier estimate of the median time to diagnosis of hepatic steatosis was 15 years. Liver disease progressed to cirrhosis in nine patients (12.5%). Liver disease was more severe in congenital lipodystrophy type 2 (CGL2). Proteinuric chronic kidney disease (CKD) developed in 32 patients (44.4%) and cardiac disease in 23 patients (31.9%). Kaplan-Meier estimates of the median time to diagnosis of CKD and cardiac disease were 25 and 45 years, respectively. Females appeared to have a more severe metabolic disease, with an earlier onset of metabolic abnormalities. Ten patients died during the follow-up period. Causes of death were end-stage renal disease, sepsis (because of recurrent intestinal perforations, coronavirus disease, diabetic foot infection and following coronary artery bypass graft surgery), myocardial infarction, heart failure because of dilated cardiomyopathy, stroke, liver complications and angiosarcoma. CONCLUSIONS: Standard treatment approaches have only a limited impact and do not prevent the development of severe metabolic abnormalities and early onset of organ complications in GL.

Loss of thymidine phosphorylase activity disrupts adipocyte differentiation and induces insulin-resistant lipoatrophic diabetes.

BACKGROUND: Thymidine phosphorylase (TP), encoded by the TYMP gene, is a cytosolic enzyme essential for the nucleotide salvage pathway. TP catalyzes the phosphorylation of the deoxyribonucleosides, thymidine and 2'-deoxyuridine, to thymine and uracil. Biallelic TYMP variants are responsible for Mitochondrial NeuroGastroIntestinal Encephalomyopathy (MNGIE), an autosomal recessive disorder characterized in most patients by gastrointestinal and neurological symptoms, ultimately leading to death. Studies on the impact of TYMP variants in cellular systems with relevance to the organs affected in MNGIE are still scarce and the role of TP in adipose tissue remains unexplored. METHODS: Deep phenotyping was performed in three patients from two families carrying homozygous TYMP variants and presenting with lipoatrophic diabetes. The impact of the loss of TP expression was evaluated using a CRISPR-Cas9-mediated TP knockout (KO) strategy in human adipose stem cells (ASC), which can be differentiated into adipocytes in vitro. Protein expression profiles and cellular characteristics were investigated in this KO model. RESULTS: All patients had TYMP loss-of-function variants and first presented with generalized loss of adipose tissue and insulin-resistant diabetes. CRISPR-Cas9-mediated TP KO in ASC abolished adipocyte differentiation and decreased insulin response, consistent with the patients' phenotype. This KO also induced major oxidative stress, altered mitochondrial functions, and promoted cellular senescence. This translational study identifies a new role of TP by demonstrating its key regulatory functions in adipose tissue. CONCLUSIONS: The implication of TP variants in atypical forms of monogenic diabetes shows that genetic diagnosis of lipodystrophic syndromes should include TYMP analysis. The fact that TP is crucial for adipocyte differentiation and function through the control of mitochondrial homeostasis highlights the importance of mitochondria in adipose tissue biology.

Therapeutic indications and metabolic effects of metreleptin in patients with lipodystrophy syndromes: Real-life experience from a national reference network.

AIM: To describe baseline characteristics and follow-up data in patients with lipodystrophy syndromes treated with metreleptin in a national reference network, in a real-life setting. PATIENTS AND METHODS: Clinical and metabolic data from patients receiving metreleptin in France were retrospectively collected, at baseline, at 1 year and at the latest follow-up during treatment. RESULTS: Forty-seven patients with lipodystrophy including generalized lipodystrophy (GLD; n = 28) and partial lipodystrophy (PLD; n = 19) received metreleptin over the last decade. At baseline, the median (interquartile range [IQR]) patient age was 29.3 (16.6-47.6) years, body mass index was 23.8 (21.2-25.7) kg/m2 and serum leptin was 3.2 (1.0-4.9) ng/mL, 94% of patients had diabetes (66% insulin-treated), 53% had hypertension and 87% had dyslipidaemia. Metreleptin therapy, administered for a median (IQR) of 31.7 (14.2-76.0) months, was ongoing in 77% of patients at the latest follow-up. In patients with GLD, glycated haemoglobin (HbA1c) and fasting triglyceride levels significantly decreased from baseline to 1 year of metreleptin treatment, from 8.4 (6.5-9.9)% [68 (48-85) mmol/mol] to 6.8 (5.6-7.4)% [51(38-57) mmol/mol], and 3.6 (1.7-8.5) mmol/L to 2.2 (1.1-3.7) mmol/L, respectively (P < 0.001), with sustained efficacy thereafter. In patients with PLD, HbA1c was not significantly modified (7.7 [7.1-9.1]% [61 (54-76) mmol/mol] at baseline vs. 7.7 [7.4-9.5]% [61(57-80) mmol/mol] at 1 year), and the decrease in fasting triglycerides (from 3.3 [1.9-9.9] mmol/L to 2.5 [1.6-5.3] mmol/L; P < 0.01) was not confirmed at the latest assessment (5.2 [2.2-11.3] mmol/L). However, among PLD patients, at 1 year, 61% were responders regarding glucose homeostasis, with lower baseline leptin levels compared to nonresponders, and 61% were responders regarding triglyceridaemia. Liver enzymes significantly decreased only in the GLD group. CONCLUSIONS: In this real-life setting study, metabolic outcomes are improved by metreleptin therapy in patients with GLD. The therapeutic indication for metreleptin needs to be clarified in patients with PLD.

Lessons from the impact of COVID-19 on medical educational continuity and practices.

The COVID-19 crisis necessitated abrupt transition to remote learning in medical schools. We aimed to assess the impact of COVID-19 on French undergraduate students and teachers, to identify practice changes, and to evaluate successes and areas for improvement of this remote learning experience. Data from 2 online questionnaires were analyzed with 509 participants among students and 189 among teachers from Sorbonne University. Responses to multiple choice, Likert response scale, and open-ended questions were evaluated. COVID-19 had negative impact on teaching continuity. Sixty-seven percent of students were in a dropout situation, and many suffered from psychological stress, leading to set up of a psychological support unit. Although most teachers (81%) and students (72%) had limited knowledge of digital resources, distance learning was quickly implemented, with a predominant use of Zoom. The analysis of several parameters revealed that students were significantly more satisfied than teachers by remote learning. Nevertheless, both students and teachers agreed to replace classical lectures by digital media and to promote in-person teaching in small interactive groups. This paper shares tips for faculty rapidly establishing remote learning. This comparative study of the students' and teachers' points of view underlines that new medical curricula should include more digital contents. We make recommendations regarding general university organization, equipment, and curricular development for long-term implementation of digital resources with reinforced relationships between faculty and students.

Genetic contribution of ABCC2 to Dubin-Johnson syndrome and inherited cholestatic disorders.

BACKGROUND AND AIMS: The ABCC2 gene is implicated in Dubin-Johnson syndrome (DJS), a rare autosomal recessive liver disorder. The primary aim of this study was to determine the diagnostic value of ABCC2 genetic testing in the largest cohort of DJS reported to date. The high number of patients with cholestatic manifestations in this series prompted us to evaluate the genetic contribution of rare, potentially pathogenic ABCC2 variants to other inherited cholestatic disorders. METHODS: The cohort study included 32 patients with clinical DJS diagnosis, and 372 patients referred for the following disorders: low phospholipid-associated cholelithiasis (LPAC) syndrome, intrahepatic cholestasis of pregnancy (ICP) and benign recurrent intrahepatic cholestasis (BRIC). ABCC2 was screened by next-generation sequencing. RESULTS: Most patients with clinical DJS had positive genetic diagnosis (n = 30; 94%), with a great diversity of point mutations and copy number variations in ABCC2. Strikingly, eight (27%) of these patients showed transient cholestatic features at presentation: four neonatal cholestasis, two ICP, one contraceptive-induced cholestasis and one sporadic cholestasis. Conversely, the frequency of rare, heterozygous, potentially pathogenic ABCC2 variants in patients with LPAC, ICP or BRIC did not differ significantly from that of the general population. CONCLUSIONS: This large series reveals that DJS is a highly homogeneous Mendelian disorder involving a large spectrum of ABCC2 variants. Genetic testing is crucial to establish early DJS diagnosis in patients with atypical presentations, such as neonatal cholestasis. This study also provides no evidence for the contribution of rare, potentially pathogenic ABCC2 variants to other inherited cholestatic disorders.

The Multifaceted Role of Epoxide Hydrolases in Human Health and Disease.

Epoxide 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.

Update on the Genetics of Autoinflammatory Disorders.

PURPOSE OF THE REVIEW: This review aims at presenting the most significant data obtained in the field of the genetics of autoinflammatory disorders (AID) over the last past 5 years. RECENT FINDINGS: More than 15 genes have been implicated in AID since 2014, unveiling new pathogenic pathways. Recent data have revealed atypical modes of transmission in several inherited AID, such as somatic mosaicism and digenism. First pieces of evidence showing an involvement of epigenetic modifications in the pathogenesis of AID have also been brought to light. Novel genetic data have been obtained on the molecular bases of genetically complex AID. The development of next-generation sequencing in routine clinical practice has led to an explosion in the identification of new AID genes. Advances in the knowledge of AID further blur the limits between monogenic and multifactorial forms of these syndromes, and between autoinflammatory and autoimmune conditions.

LMNA-associated partial lipodystrophy: anticipation of metabolic complications.

BACKGROUND: Type-2 familial partial lipodystrophy (FPLD2) is a rare autosomal dominant lipodystrophic disorder due to mutations in LMNA encoding lamin A/C, a key epigenetic regulator. FPLD2 severity is determined by the occurrence of metabolic complications, especially diabetes and hypertriglyceridaemia. We evaluated the disease history and severity over generations. METHODS: This retrospective study of the largest cohort of patients with FPLD2 reported to date investigates 85 patients from 24 families comprising three generations (G1: n=39; G2: n=41; G3: n=5). RESULTS: Lipodystrophy appears with the same characteristics and at the same age in first generation (G1;18.6±1.5 years) and second generation (G2;15.9±0.8 years). Despite similar body mass index (23.7±0.6 vs 23.8±0.6 kg/m2), the mean delay between the onset of lipodystrophy and diabetes was far shorter in G2 (10.5±2.4 years) than in G1 (29.0±3.5 years) (p=0.0002). The same is true for the delay preceding hypertriglyceridaemia (G2: 4.5±1.4; G1: 19.3±3.2 years) (p=0.002), revealing an anticipation phenomenon. Observations in G3, and analysis within each family of disease history and diagnostic procedures, confirmed this result. CONCLUSIONS: This study is a rare example of anticipation unrelated to a trinucleotide expansion. Discovery of this early occurrence of metabolic complications in young generations underlines the utility of presymptomatic genetic diagnosis, with careful metabolic screening and preventive lifestyle in all at-risk individuals.

Familial Mediterranean fever in heterozygotes: are we able to accurately diagnose the disease in very young children?

OBJECTIVE: 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.

Patients' perspective on the medical pathway from first symptoms to diagnosis in genetic lipodystrophy.

OBJECTIVE: Underdiagnosis is an important issue in genetic lipodystrophies, which are rare diseases with metabolic, cardiovascular, gynecological, and psychological complications. We aimed to characterize the diagnostic pathway in these diseases from the patients' perspective. DESIGN: Cross-sectional study conducted through a self-reported patient questionnaire. METHODS: Patients with genetic lipodystrophy were recruited throughout the French national reference network for rare diseases of insulin secretion and insulin sensitivity. Patients completed a self-reported questionnaire on disease symptoms, steps leading to the diagnosis, and healthcare professionals involved. Descriptive analyses were conducted. RESULTS: Out of 175 eligible patients, 109 patients (84% women) were included; 93 had partial familial lipodystrophy and 16 congenital generalized lipodystrophy. Metabolic comorbidities (diabetes 68%, hypertriglyceridemia 66%, hepatic steatosis 57%), cardiovascular (hypertension 54%), and gynecologic complications (irregular menstruation 60%) were frequently reported. Median age at diagnosis was 30 years (interquartile range [IQR] 23-47). The overall diagnostic process was perceived as "very difficult" for many patients. It extended over 12 years (IQR 5-25) with more than five different physicians consulted by 36% of respondents, before diagnosis, for lipodystrophy-related symptoms. The endocrinologist made the diagnosis for 77% of the patients. Changes in morphotype were reported as the first symptoms by the majority of respondents. CONCLUSIONS: Diagnostic pathway in patients with genetic lipodystrophy is rendered difficult by the multisystemic features of the disease and the lack of knowledge of non-specialized physicians. Training physicians to systematically include adipose tissue examination in routine clinical evaluation should improve diagnosis and management of lipodystrophy and lipodystrophy-associated comorbidities.

Ciliopathy due to POC1A deficiency: clinical and metabolic features, and cellular modeling.

OBJECTIVE: SOFT syndrome (MIM#614813), denoting Short stature, Onychodysplasia, Facial dysmorphism, and hypoTrichosis, is a rare primordial dwarfism syndrome caused by biallelic variants in POC1A, encoding a centriolar protein. SOFT syndrome, characterized by severe growth failure of prenatal onset and dysmorphic features, was recently associated with insulin resistance. This study aims to further explore its endocrinological features and pathophysiological mechanisms. DESIGN/METHODS: We present clinical, biochemical, and genetic features of 2 unrelated patients carrying biallelic pathogenic POC1A variants. Cellular models of the disease were generated using patients' fibroblasts and POC1A-deleted human adipose stem cells. RESULTS: Both patients present with clinical features of SOFT syndrome, along with hyperinsulinemia, diabetes or glucose intolerance, hypertriglyceridemia, liver steatosis, and central fat distribution. They also display resistance to the effects of IGF-1. Cellular studies show that the lack of POC1A protein expression impairs ciliogenesis and adipocyte differentiation, induces cellular senescence, and leads to resistance to insulin and IGF-1. An altered subcellular localization of insulin receptors and, to a lesser extent, IGF1 receptors could also contribute to resistance to insulin and IGF1. CONCLUSIONS: Severe growth retardation, IGF-1 resistance, and centripetal fat repartition associated with insulin resistance-related metabolic abnormalities should be considered as typical features of SOFT syndrome caused by biallelic POC1A null variants. Adipocyte dysfunction and cellular senescence likely contribute to the metabolic consequences of POC1A deficiency. SOFT syndrome should be included within the group of monogenic ciliopathies with metabolic and adipose tissue involvement, which already encompasses Bardet-Biedl and Alström syndromes.

Proceedings of the annual meeting of the European Consortium of Lipodystrophies (ECLip), Pisa, Italy, 28-29 September 2023.

Lipodystrophy syndromes are rare diseases primarily affecting the development or maintenance of the adipose tissue but are also distressing indirectly multiple organs and tissues, often leading to reduced life expectancy and quality of life. Lipodystrophy syndromes are multifaceted disorders caused by genetic mutations or autoimmunity in the vast majority of cases. While many subtypes are now recognized and classified, the disease remains remarkably underdiagnosed. The European Consortium of Lipodystrophies (ECLip) was founded in 2014 as a non-profit network of European centers of excellence working in the field of lipodystrophies aiming at promoting international collaborations to increase basic scientific understanding and clinical management of these syndromes. The network has developed a European Patient Registry as a collaborative research platform for consortium members. ECLip and ECLip registry activities involve patient advocacy groups to increase public awareness and to seek advice on research activities relevant from the patients perspective. The annual ECLip congress provides updates on the research results of various network groups members.

Perinatal, metabolic, and reproductive features in PPARG-related lipodystrophy.

OBJECTIVE: The adipogenic PPARG-encoded PPARγ nuclear receptor also displays essential placental functions. We evaluated the metabolic, reproductive, and perinatal features of patients with PPARG-related lipodystrophy. METHODS: Current and retrospective data were collected in patients referred to a National Rare Diseases Reference Centre. RESULTS: 26 patients from 15 unrelated families were studied (18 women, median age 43 years). They carried monoallelic PPARG variants except a homozygous patient with congenital generalized lipodystrophy. Among heterozygous patients aged 16 or more (n = 24), 92% had diabetes, 96% partial lipodystrophy (median age at diagnosis 24 and 37 years), 78% hypertriglyceridaemia, 71% liver steatosis, and 58% hypertension. The mean BMI was 26 ± 5.0 kg/m2. Women (n = 16) were frequently affected by acute pancreatitis (n = 6) and/or polycystic ovary syndrome (n = 12). Eleven women obtained one or several pregnancies, all complicated by diabetes (n = 8), hypertension (n = 4), and/or hypertriglyceridaemia (n = 10). We analysed perinatal data of patients according to the presence (n = 8) or absence (n = 9) of a maternal dysmetabolic environment. The median gestational age at birth was low in both groups (37 and 36 weeks of amenorrhea, respectively). As expected, the birth weight was higher in patients exposed to a foetal dysmetabolic environment of maternal origin. In contrast, 85.7% of non-exposed patients, in whom the variant is, or is very likely to be, paternally-inherited, were small for gestational age. CONCLUSIONS: Lipodystrophy-related PPARG variants induce early metabolic complications. Our results suggest that placental expression of PPARG pathogenic variants carried by affected foetuses could impair prenatal growth and parturition. This justifies careful pregnancy monitoring in affected families.

Lipoatrophic diabetes in familial partial lipodystrophy type 2: From insulin resistance to diabetes.

AIM: Subjects with Familial Partial Lipodystrophy type 2 (FPLD2) are at high risk to develop diabetes. To better understand the natural history and variability of this disease, we studied glucose tolerance, insulin response to an oral glucose load, and metabolic markers in the largest cohort to date of subjects with FPLD2 due to the same LMNA variant. METHODS: A total of 102 patients aged > 18 years, with FPLD2 due to the LMNA 'Reunionese' variant p.(Thr655Asnfs*49) and 22 unaffected adult relatives with normal glucose tolerance (NGT) were enrolled. Oral Glucose Tolerance Tests (OGTT) with calculation of derived insulin sensitivity and secretion markers, and measurements of HbA1c, C-reactive protein, leptin, adiponectin and lipid profile were performed. RESULTS: In patients with FPLD2: 65% had either diabetes (41%) or prediabetes (24%) despite their young age (median: 39.5 years IQR 29.0-50.8) and close-to-normal BMI (median: 25.5 kg/m2 IQR 23.1-29.4). Post-load OGTT values revealed insulin resistance and increased insulin secretion in patients with FPLD2 and NGT, whereas patients with diabetes were characterized by decreased insulin secretion. Impaired glucose tolerance with normal fasting glucose was present in 86% of patients with prediabetes. Adiponectin levels were decreased in all subjects with FPLD2 and correlated with insulin sensitivity markers. CONCLUSIONS: OGTT reveals early alterations of glucose and insulin metabolism in patients with FPLD2, and should be systematically performed before excluding a diagnosis of prediabetes or diabetes to adapt medical care. Decreased adiponectin is an early marker of the disease. Adiponectin replacement therapy warrants further study in FPLD2.

Loss of phospholipase PLAAT3 causes a mixed lipodystrophic and neurological syndrome due to impaired PPARγ signaling.

Phospholipase A/acyltransferase 3 (PLAAT3) is a phospholipid-modifying enzyme predominantly expressed in neural and white adipose tissue (WAT). It is a potential drug target for metabolic syndrome, as Plaat3 deficiency in mice protects against diet-induced obesity. We identified seven patients from four unrelated consanguineous families, with homozygous loss-of-function variants in PLAAT3, who presented with a lipodystrophy syndrome with loss of fat varying from partial to generalized and associated with metabolic complications, as well as variable neurological features including demyelinating neuropathy and intellectual disability. Multi-omics analysis of mouse Plaat3-/- and patient-derived WAT showed enrichment of arachidonic acid-containing membrane phospholipids and a strong decrease in the signaling of peroxisome proliferator-activated receptor gamma (PPARγ), the master regulator of adipocyte differentiation. Accordingly, CRISPR-Cas9-mediated PLAAT3 inactivation in human adipose stem cells induced insulin resistance, altered adipocyte differentiation with decreased lipid droplet formation and reduced the expression of adipogenic and mature adipocyte markers, including PPARγ. These findings establish PLAAT3 deficiency as a hereditary lipodystrophy syndrome with neurological manifestations, caused by a PPARγ-dependent defect in WAT differentiation and function.

Dramatic beneficial effect of interleukin-1 inhibitor treatment in patients with familial Mediterranean fever complicated with amyloidosis and renal failure.

BACKGROUND: Familial Mediterranean fever (FMF) is an autosomal recessive autoinflammatory disorder, for which systemic AA amyloidosis is the major complication revealed most of the time by renal abnormalities. Current treatment is daily colchicine that prevents both recurrent inflammatory attacks and amyloidosis deposition in most patients. However, some patients still develop amyloidosis and renal failure. Functional studies suggest that interleukin (IL)-1 is implicated in the inflammatory reaction in FMF and therefore, IL-1 inhibitors could be a new approach to treat FMF. The aim of this series study was to evaluate anakinra in patients with FMF complicated with amyloidosis and renal failure. METHODS: We studied a series of adult patients with FMF complicated with amyloidosis and treated with anakinra in one reference centre were reviewed. A search for published patients with FMF associated amyloidosis treated with anakinra was performed by screening PubMed. RESULTS: We report four cases of patients with FMF-associated amyloidosis treated with anakinra and discuss the clinical pertinence of its use in these particular clinical settings. CONCLUSIONS: Anakinra has a strong effect on both inflammatory attacks and general status in patients with FMF-associated amyloidosis. It may contribute to changing the prognosis of these patients. Long-term studies are needed to appreciate the effect of anakinra or other IL-1 inhibitors on the natural history of amyloidosis in these patients.

Identification and functional consequences of a recurrent NLRP12 missense mutation in periodic fever syndromes.

OBJECTIVE: To gain insight into the molecular bases of genetically unexplained periodic fever syndromes (PFS) by screening NLRP12, a gene in which only a nonsense and a splice site mutation have so far been identified, and to assess the functional consequences of the identified missense variation. METHODS: NLRP12 was screened for mutations by direct sequencing. Functional assays were performed in HEK 293T cells stably expressing the proapoptotic protein ASC and procaspase 1, in order to determine the effects of normal and mutated NLRP12 proteins on speck formation, caspase 1 signaling, and NF-κB activation. RESULTS: A heterozygous NLRP12 missense mutation involving a CpG site (c.1054C>T; p.Arg352Cys) was identified in exon 3, which encodes the nucleotide-binding site (NBS) of the protein, in 2 patients from different countries and carrying different NLRP12 haplotypes. The mutation, which does not alter the inhibitory effect of NLRP12 on NF-κB activation, increases speck formation and activates caspase 1 signaling. To define this new class of PFS, we propose the term NLRP12-associated disorders (NLRP12AD). CONCLUSION: Given the rarity of known NLRP12-associated disorders, the identification of this NLRP12 molecular defect contributes to the delineation of the clinical spectrum associated with mutations in this gene and highlights the importance of screening NLRP12 in patients presenting with unexplained PFS. This study also demonstrates, by means of functional assays, the deleterious effect of this recurrent missense mutation; the gain of function for speck formation and caspase 1 signaling associated with this NBS mutation is consistent with the inflammatory phenotype of PFS.