Chanarin-Dorfman syndrome: Genotype-Phenotype Correlation

Dorfman-Chanarin Syndrome with Renal Involvement: A Rare Case Report and Literature Review

Dorfman-Chanarin syndrome (DCS) is a rare autosomal recessive disease. It is a multisystemic disease in which renal involvement is uncommon. We report the case of a woman with nephrotic syndrome associated with DCS. A 36-year-old woman was referred to the nephrology department for edema with known history for DCS. On physical examination, she had ichthyosiform erythroderma with generalized scaly skinand ascites. The ophthalmologic examination revealed a cataract in the right eye. Abdominal ultrasound examination showed hepatomegaly and splenomegaly. Laboratory tests showed normal renal and liver function. The blood cell count showed pancytopenia. Immunologic exams showed the presence of anti-mitochondrial antibodies. Kidney biopsy showed mesangial proliferative glomerulonephritis with extensive lipid vacuoles in the tubular epithelial cells. Immunofluorescence study showed mesangial deposits of IgG, C3, kappa, and lambda. To the best of our knowledge, this is the first case of DCS with renal involvement reported in an adult.

Biogenesis and Lipase-Mediated Mobilization of Lipid Droplets in Plants

Cytosolic lipid droplets (LDs) derived from the endoplasmic reticulum (ER) mainly contain neutral lipids, such as triacylglycerols (TAGs) and sterol esters, which are considered energy reserves. The metabolic pathways associated with LDs in eukaryotic species are involved in diverse cellular functions. TAG synthesis in plants is mediated by the sequential involvement of two subcellular organelles, i.e., plastids - plant-specific organelles, which serve as the site of lipid synthesis, and the ER. TAGs and sterol esters synthesized in the ER are sequestered to form LDs through the cooperative action of several proteins, such as SEIPINs, LD-associated proteins, LDAP-interacting proteins, and plant-specific proteins such as oleosins. The integrity and stability of LDs are highly dependent on oleosins, especially in the seeds, and oleosin degradation is critical for efficient mobilization of the TAGs of plant LDs. As the TAGs mobilize in LDs during germination and post-germinative growth, a plant-specific lipase-sugar-dependent 1 (SDP1)-plays a major role, through the inter-organellar communication between the ER and peroxisomes. In this review, we briefly recapitulate the different processes involved in the biogenesis and degradation of plant LDs, followed by a discussion of future perspectives in this field.

Case Report: Chanarin-Dorfman Syndrome: A Novel Homozygous Mutation in ABHD5 Gene in a Chinese Case and Genotype-Phenotype Correlation Analysis

The Chanarin-Dorfman syndrome (CDS) is a rare, autosomal recessively inherited genetic disease, whch is associated with a decrease in the lipolysis activity in multiple tissue cells. The clinical phenotype involves multiple organs and systems, including liver, eyes, ears, skeletal muscle and central nervous system. Mutations in ABHD5/CGI58 gene have been confirmed to be associated with CDS. We performed whole exome sequencing on a Chinese CDS patient with skin ichthyosis features mimicking lamellar ichthyosis, ectropion, sensorineural hearing loss, and lipid storage in peripheral blood neutrophils. A novel homozygous missense mutation (p.L154R) in ABHD5 gene was detected in this patient. Genotype-phenotype analysis in reported CDS patients revealed no particular correlation. Our findings further enrich the reservoir of ABHD5 mutations in CDS.

Chanarin–Dorfman syndrome: clinical/genetic features and natural history in six Pakistani patients

Background

Chanarin–Dorfman syndrome (CDS; OMIM # 275630) is a rare neutral lipid storage disorder caused by mutation in ABHD5 (a/b hydrolase domain containing 5″) a cofactor for adipose triglyceride lipase (ATGL) resulting in intracellular accumulation of triacylglycerol (TG) in numerous body tissues. It is an autosomal recessive disorder mutation in ABHD5 that causes the partial or total loss of ATGL activation, leading to the accumulation of TG inside lipid droplets. We aim to assess the clinical and biochemical manifestations, diagnosis, follow-up and genotype–phenotype correlations in six Pakistani pediatric patients with CDS.

Results

Six male patients with mean age 15 months (9–24 months) diagnosed as CDS on the basis of non-bullous ichthyosiform erythroderma, hepatomegaly and Jordans bodies in peripheral smear. We identified two novel mutations in ABHD5 gene (c.338G > T and c.730_731insA). These mutations have a pathogenic and damaging influence on the ABHD5 protein structure and function. During the 2 year clinical follow-up one patient died of severe chest infection; he had severe phenotype. There is no genotype–phenotype correlation in CDS. Therapy with low fat diet, MCT oil, Vit E and ursodeoxycholic acid has promising results in CDS.

Conclusion

Non-bullous ichthyosiform erythroderma, steatohepatitis and Jordan’s anomaly are consistent findings in all cases of CDS. It is suggested that an accurate diagnosis of CDS should be based on combination of clinical features and pathognomonic ABHD5 mutations. More studies should be carried out to identify population-specific genetic mutations for the rapid and cost-effective diagnosis of CDS.

An Adolescent with Chanarin-Dorfman Syndrome Presenting with Ichthyosis and Hepatic Steatosis

Chanarin-Dorfman syndrome also known as neutral lipid storage disease is a rare multisystemic autosomal recessive disorder. It is mostly encountered in patients of Mediterranean and Middle Eastern origin. Most patients are brought to medical attention secondary to dermatological manifestations namely ichthyosis. Here, we report a 10-year-old Kurdish male patient with ichthyosis, who was referred to pediatric liver clinic for transaminase elevation of unknown etiology despite elaborate workup. Histological findings on liver biopsy were consistent with nonalcoholic steatohepatitis. Genetic testing identified homozygous mutation C.776G>A (p.G259D) in the Abhydrolase domain containing 5 gene on chromosome 3 described in patients with Chanarin-Dorfman syndrome. After the initiation of a diet with high medium chain triglycerides/long chain triglycerides ratio, aerobic exercise, and vitamin E, the patient liver enzymes improved. Due to debilitating ichthyosis, he was started on acitretin therapy that was discontinued due to transaminases elevation. Patient is currently stable and doing well.

Dorfman-Chanarin Syndrome: A Rare Cause of Metabolic Associated Fatty Liver Disease Related to Homozygosity of the Nonsense Mutation c.934C>T (p.R312*)

Metabolic associated fatty liver disease became the most common form of chronic liver disease, in the vast majority of the cases related to increased insulin resistance or metabolic dysregulation. Yet, other causes may be implied. We report the late diagnosis of Dorfman-Chanarin syndrome in a non-alcoholic steatohepatitis previously labeled cirrhotic middle-aged man, with consanguineous parents, complicated with hepatocellular carcinoma. Congenital ichthyosis, neurosensory hearing loss and elevated muscular enzymes hit on the track of Dorfman-Chanarin syndrome. The genetic analysis uncovered a first-time described homozygotic nonsense mutation in the ABHD5 gene, responsible for coding the ABHD5 protein. The patient was successfully submitted to liver transplantation. Inborn errors of metabolism are a rare cause of metabolic associated fatty liver disease, but they need to be kept in consideration in all patients who present with atypical clinical features. This shall raise the awareness of physicians to rare forms of presentation since it may imply not only a different prognosis, but also other actions, like particular therapies as liver transplantation due to related complications of cirrhosis, or familial screening.

Recurrent N209* ABHD5 mutation in two unreported families with Chanarin Dorfman Syndrome

ABHD5 protein is widely involved in lipid and energy homeostasis. Mutations in the ABHD5 gene are associated with the onset of Neutral Lipid Storage Disease with Ichthyosis (NLSDI), historically known as Chanarin Dorfman Syndrome (CDS). CDS is a rare autosomal recessive lipid storage disease, characterized by non-bullous congenital ichthyosiform eritrhoderma (NCIE), hepatomegaly and liver steatosis. Myopathy, neurosensory hearing loss, cataracts, nystagmus, strabismus, and mental impairment are considered additional findings. To date, 151 CDS patients have been reported all over the world. Here we described two additional families with patients affected by CDS from Turkey. Our patients were a 42 and 22-years old men, admitted to the Hospital for congenital ichthyosis. Hepatic steatosis and myopathy were also detected in both patients. ABHD5 molecular analysis revealed the presence of N209* mutation. Our data enlarge the cohort of CDS patients and provide a revision of muscle clinical findings for this rare inborn error of neutral lipid metabolism.

Chanarin-Dorfman Syndrome: A comprehensive review

The Chanarin-Dorfman syndrome (CDS) is a rare, autosomal recessively inherited genetic disease. This syndrome is associated with a decrease in the lipolysis activity in multiple tissue cells because of recessive mutations in the abhydrolase domain containing 5 (ABHD5) gene, which leads to the accumulation of lipid droplets in multiple types of cells. Major clinical symptoms in patients with CDS include ichthyosis and intracytoplasmic lipid droplets. The variability of clinical symptoms in patients with CDS depends on a large number of mutations involved. In this syndrome, liver involvement is an important cause of mortality and morbidity. This review aims to summarize the demographic characteristic, clinical symptoms, liver involvement and mutations in CDS patients in the literature to date.

Friend or Foe: Lipid Droplets as Organelles for Protein and Lipid Storage in Cellular Stress Response, Aging and Disease

Lipid droplets (LDs) were considered as a mere lipid storage organelle for a long time. Recent evidence suggests that LDs are in fact distinct and dynamic organelles with a specialized proteome and functions in many cellular roles. As such, LDs contribute to cellular signaling, protein and lipid homeostasis, metabolic diseases and inflammation. In line with the multitude of functions, LDs interact with many cellular organelles including mitochondria, peroxisomes, lysosomes, the endoplasmic reticulum and the nucleus. LDs are highly mobile and dynamic organelles and impaired motility disrupts the interaction with other organelles. The reduction of interorganelle contacts results in a multitude of pathophysiologies and frequently in neurodegenerative diseases. Contacts not only supply lipids for β-oxidation in mitochondria and peroxisomes, but also may include the transfer of toxic lipids as well as misfolded and harmful proteins to LDs. Furthermore, LDs assist in the removal of protein aggregates when severe proteotoxic stress overwhelms the proteasomal system. During imbalance of cellular lipid homeostasis, LDs also support cellular detoxification. Fine-tuning of LD function is of crucial importance and many diseases are associated with dysfunctional LDs. We summarize the current understanding of LDs and their interactions with organelles, providing a storage site for harmful proteins and lipids during cellular stress, aging inflammation and various disease states.

CGI-58: Versatile Regulator of Intracellular Lipid Droplet Homeostasis

Comparative gene identification-58 (CGI-58), also known as α/β-hydrolase domain-containing 5 (ABHD5), is a member of a large family of proteins containing an α/β-hydrolase-fold. CGI-58 is well-known as the co-activator of adipose triglyceride lipase (ATGL), which is a key enzyme initiating cytosolic lipid droplet lipolysis. Mutations in either the human CGI-58 or ATGL gene cause an autosomal recessive neutral lipid storage disease, characterized by the excessive accumulation of triglyceride (TAG)-rich lipid droplets in the cytoplasm of almost all cell types. CGI-58, however, has ATGL-independent functions. Distinct phenotypes associated with CGI-58 deficiency commonly include ichthyosis (scaly dry skin), nonalcoholic steatohepatitis, and hepatic fibrosis. Through regulated interactions with multiple protein families, CGI-58 controls many metabolic and signaling pathways, such as lipid and glucose metabolism, energy balance, insulin signaling, inflammatory responses, and thermogenesis. Recent studies have shown that CGI-58 regulates the pathogenesis of common metabolic diseases in a tissue-specific manner. Future studies are needed to molecularly define ATGL-independent functions of CGI-58, including the newly identified serine protease activity of CGI-58. Elucidation of these versatile functions of CGI-58 may uncover fundamental cellular processes governing lipid and energy homeostasis, which may help develop novel approaches that counter against obesity and its associated metabolic sequelae.

A novel mutation of ABHD5 gene in a Chanarin Dorfman patient with unusual dermatological findings

Background

Chanarin Dorfman Syndrome (CDS) is a rare autosomal recessive disorder characterized by the multisytemic accumulation of neutral lipids inside the cytoplasmic lipid droplets. This condition is caused by mutations in the abhydrolase domain containing 5 gene (ABHD5). In CDS the skin involvement is the prevalent and always observed clinical feature, consisting of a non-bullous congenital ichthyosiform erythroderma (NCIE). Moreover, a variable involvement of the liver and neuromuscular system can be also observed. In this report, we aimed to perform the clinical and genetic characterization of a patient affected by CDS with atypical dermatological findings, considering this rare inborn error of neutral lipid metabolism.

Methods

Genomic DNA samples obtained from patient and his parents were used to perform the sequencing of the ABHD5 exons and their intron/exon boundaries. Bioinformatic analyses were performed to investigate the possible effect of the identified mutation on protein structure.

Results

Here we present the case of a 29-year-old male patient with CDS, who, for long time, has been misdiagnosed as pityriasis rubra pilaris (PRP). He has a history of increasing hyperlipidemia; hepatomegaly associated with hepatosteatosis was also detected. ABHD5 molecular analysis revealed a novel missense mutation, the c.811G > A (p.G271R). Bioinformatic investigations showed that the variant has a deleterious effect on ABHD5 function, probably causing an incorrect folding of the mutant protein.

Conclusions

These results highlihts the importance of genetic testing for ABHD5 in unresolved cases of patients presenting unusual skin lesions, that resemble PRP, associated with a history of hyperlipidemia and nonalcoholic fatty liver.

Thyroid involvement in Chanarin-Dorfman syndrome in adults in the largest series of patients carrying the same founder mutation in ABHD5 gene

Background

Chanarin-Dorfman syndrome (CDS) is a rare syndromic disease related to an accumulation of triacylglycerol in most organs. The aim of our study was to investigate various organs in a large series of CDS patients.

Results

We report for the first time thyroid function impairment in CDS. Among 12 investigated patients, 7 showed thyroid function impairment. All of them were over 30 of age. The 5 remaining investigated patients with normal thyroid function were under 30. Thyroid loss of function is an unknown clinical feature of CDS that could gradually develop with age. Thyroid ultrasound showed an abnormal aspect in all investigated patients (6 with thyroid impairment and 3 with normal thyroid function). Cervical MRI done in 2 patients with thyroid impairment showed fat infiltration of thyroid parenchyma. Audiogram carried out in 8 of our patients showed sensorineural hearing impairment in all patients, although only 2 patients suffered from clinical hypoacusia. We also demonstrated that kidney could be a more commonly involved organ than previously reported in the literature. A poorly differentiated kidney parenchyma is a common feature in our series. One patient showed cerebellar atrophy and T2 hypersignal of brain’s white matter in MRI. All patients carried the same founder mutation c.773(− 1)G > A in the ABDH5 gene.

Discussion

Aside from the congenital ichthyosiform erythroderma, the most common symptom of CDS, in addition to other organs involvement frequently reported in the literature, we described thyroid dysfunction, an unreported feature, probably related to the lipid infiltration of the thyroid parenchyma. The association found between age and hypothyroidism in CDS patients could explain the gradually development of thyroid disease with age.

Conclusion

We reported a thyroid dysfunction and unreported ultrasonographic aspects of kidneys and cerebral MRI in CDS patients.

Methods

We performed clinical analyses in 15 patients in whom thyroid, liver, ocular, kidney, skeletal muscle and neurological involvement were explored. Genetic and molecular explorations were performed by direct sequence analysis. Software SPSS, Fisher’s exact test and ANOVA were used for statistical analyses.

Electronic supplementary material

The online version of this article (10.1186/s13023-019-1095-4) contains supplementary material, which is available to authorized users.

Guidance for assessment of erythroderma in neonates and infants for the pediatric immunologist

Neonatal and infantile erythroderma (NIE) represents the common clinical phenotype of heterogeneous diseases ranging from benign and transient skin conditions to fatal multiorgan disorders. NIE regularly demands a comprehensive diagnostic workup in a multiprofessional setting, especially if newborns and young infants with the disease develop a failure to thrive and concomitant infectious, neurologic, or metabolic complications. By obtaining a detailed medical history and performing a thorough clinical examination, targeted diagnostic steps can be scheduled for most affected children. If NIE occurs in the early neonatal period, lesional skin biopsy and histology are often indicated. Likewise, if monogenic skin or immunologic diseases are suspected, genetic testing with customized panels of potentially underlying genes is mandatory. Of note, if acute symptoms such as severe infections, metabolic acidosis, or seizures occur, rapid microbiologic and metabolic investigations are warranted to rule out immunodeficiency and inborn errors of metabolism.

Neutral Lipid Storage Diseases as Cellular Model to Study Lipid Droplet Function

Neutral lipid storage disease with myopathy (NLSDM) and with ichthyosis (NLSDI) are rare autosomal recessive disorders caused by mutations in the PNPLA2 and in the ABHD5/CGI58 genes, respectively. These genes encode the adipose triglyceride lipase (ATGL) and α-β hydrolase domain 5 (ABHD5) proteins, which play key roles in the function of lipid droplets (LDs). LDs, the main cellular storage sites of triacylglycerols and sterol esters, are highly dynamic organelles. Indeed, LDs are critical for both lipid metabolism and energy homeostasis. Partial or total PNPLA2 or ABHD5/CGI58 knockdown is characteristic of the cells of NLSD patients; thus, these cells are natural models with which one can unravel LD function. In this review we firstly summarize genetic and clinical data collected from NLSD patients, focusing particularly on muscle, skin, heart, and liver damage due to impaired LD function. Then, we discuss how NLSD cells were used to investigate and expand the current structural and functional knowledge of LDs.

Chanarin-Dorfman syndrome

Chanarin Dorfman syndrome is a multisystem, very rare, autosomal recessive lipid storage disorder, characterized by the accumulation of lipid vacuoles in neutrophils, and was first described by Dorfman in 1974. Due to a mutation in the ABHD5 gene of the short arm of chromosome 3, lipid is stored in the granulocytes at various sites in the human body, such as the muscle, liver, eye, ear, central nervous system, and bone marrow. Clinically, the disease is presented with ichthyosis, hearing loss, hepatomegaly, splenomegaly, cirrhosis, cataract, keratopathy, myopathy, and mental retardation. A 38-year-old male patient was referred to our Internal Medicine Clinic for consultation with laboratory findings as follows: high aspartate aminotransferase (AST; 203 U/L), alanine aminotransferase (ALT; 151 U/L), gamma-glutamyl transferase (GGT; 167 U/L), creatine kinase (CK; 1127 U/L) levels and low platelet levels (108000). After ultrasonography and gastroscopy, the patient was diagnosed with liver cirrhosis. Bilateral mixed-type hearing loss on audial tests and bilateral punctuate keratopathy, ectropion, and cataract in the left eye on ophthalmological tests were found. For the definitive diagnosis of Chanarin Dorfman syndrome, peripheral blood was examined, which revealed lipid accumulation in the neutrophils (Jordan's anomaly). We emphasize that if a patient has unusual findings, such as ichthyosis, hearing loss, hepatomegaly, splenomegaly, cirrhosis, cataract, keratopathy, myopathy, and mental retardation, the possibility of Chanarin Dorfman syndrome should be considered.

Lipid storage myopathies: Current treatments and future directions

Lipid storage myopathies (LSMs) are a heterogeneous group of genetic disorders that present with abnormal lipid storage in multiple body organs, typically muscle. Patients can clinically present with cardiomyopathy, skeletal muscle weakness, myalgia, and extreme fatigue. An early diagnosis is crucial, as some LSMs can be managed by simple nutraceutical supplementation. For example, high dosage l-carnitine is an effective intervention for patients with Primary Carnitine Deficiency (PCD). This review discusses the clinical features and management practices of PCD as well as Neutral Lipid Storage Disease (NLSD) and Multiple Acyl-CoA Dehydrogenase Deficiency (MADD). We provide a detailed summary of current clinical management strategies, highlighting issues of high-risk contraindicated treatments with case study examples not previously reviewed. Additionally, we outline current preclinical studies providing disease mechanistic insight. Lastly, we propose that a number of other conditions involving lipid metabolic dysfunction that are not classified as LSMs may share common features. These include Neurofibromatosis Type 1 (NF1) and autoimmune myopathies, including Polymyositis (PM), Dermatomyositis (DM), and Inclusion Body Myositis (IBM).

Clinical and genetic characterization of a Chanarin Dorfman Syndrome patient born to diseased parents

Background

Chanarin Dorfman Syndrome (CDS) is a rare autosomal recessive disorder characterized by ichthyosiform non-bullous erythroderma and variable involvement of the liver and the neuromuscular system. In CDS patients, the accumulation of neutral lipids inside cytoplasmic lipid droplets has been demonstrated in different tissues. To date, ninety families with this disease have been described worldwide; most of them are from Mediterranean countries.

Case presentation

In this report, we describe a consanguineous Turkish family with typical features of CDS. The parents are first cousins and are both diseased. At the age of eight, their child presented CDS with non-bullous congenital ichthyosiform erythroderma, hepatosteatosis, hepatomegaly and ectropion. Electromyographic examination is compatible with myopathy. A five-year-old cousin of the child is also affected by CDS. She was born to non-affected consanguineous parents. Mutation analysis of the ABHD5 gene revealed the previously reported mutation, N209X, which is the most frequent in Turkish patients. Lipid vacuoles, also known as Jordan’s anomaly, are detectable in their leucocytes.

Conclusions

To the best of our knowledge, this is the first report of a CDS family in which both parents and their child are affected by CDS. To date, the child does not present a more severe clinical phenotype compared with those of his relatives or other CDS patients of the same age. These findings suggest that high levels of triacylglycerol accumulation, that may be supposed to be present in high amount inside the ooplasm, did not affect embryo development and foetal growth.

Electronic supplementary material

The online version of this article (10.1186/s12881-018-0610-0) contains supplementary material, which is available to authorized users.

Critical roles for α/β hydrolase domain 5 (ABHD5)/comparative gene identification-58 (CGI-58) at the lipid droplet interface and beyond

Mutations in the gene encoding comparative gene identification 58 (CGI-58), also known as α β hydrolase domain-containing 5 (ABHD5), cause neutral lipid storage disorder with ichthyosis (NLSDI). This inborn error in metabolism is characterized by ectopic accumulation of triacylglycerols (TAG) within cytoplasmic lipid droplets in multiple cell types. Studies over the past decade have clearly demonstrated that CGI-58 is a potent regulator of TAG hydrolysis in the disease-relevant cell types. However, despite the reproducible genetic link between CGI-58 mutations and TAG storage, the molecular mechanisms by which CGI-58 regulates TAG hydrolysis are still incompletely understood. It is clear that CGI-58 can regulate TAG hydrolysis by activating the major TAG hydrolase adipose triglyceride lipase (ATGL), yet CGI-58 can also regulate lipid metabolism via mechanisms that do not involve ATGL. This review highlights recent progress made in defining the physiologic and biochemical function of CGI-58, and its broader role in energy homeostasis. This article is part of a Special Issue entitled: Recent Advances in Lipid Droplet Biology edited by Rosalind Coleman and Matthijs Hesselink.

Lipid Droplets in Health and Disease

Lipids are essential building blocks synthesized by complex molecular pathways and deposited as lipid droplets (LDs) in cells. LDs are evolutionary conserved organelles found in almost all organisms, from bacteria to mammals. They are composed of a hydrophobic neutral lipid core surrounding by a phospholipid monolayer membrane with various decorating proteins. Degradation of LDs provide metabolic energy for divergent cellular processes such as membrane synthesis and molecular signaling. Lipolysis and autophagy are two main catabolic pathways of LDs, which regulate lipid metabolism and, thereby, closely engaged in many pathological conditons. In this review, we first provide an overview of the current knowledge on the structural properties and the biogenesis of LDs. We further focus on the recent findings of their catabolic mechanism by lipolysis and autophagy as well as their connection ragarding the regulation and function. Moreover, we discuss the relevance of LDs and their catabolism-dependent pathophysiological conditions.

Neutral Lipid Storage Diseases: clinical/genetic features and natural history in a large cohort of Italian patients

Background

A small number of patients affected by Neutral Lipid Storage Diseases (NLSDs: NLSD type M with Myopathy and NLSD type I with Ichthyosis) have been described in various ethnic groups worldwide. However, relatively little is known about the progression and phenotypic variability of the disease in large specific populations. The aim of our study was to assess the natural history, disability and genotype-phenotype correlations in Italian patients with NLSDs. Twenty-one patients who satisfied the criteria for NLSDs were enrolled in a retrospective cross-sectional study to evaluate the genetic aspects, clinical signs at onset, disability progression and comorbidities associated with this group of diseases.

Results

During the clinical follow-up (range: 2–44 years, median: 17.8 years), two patients (9.5%, both with NLSD-I) died of hepatic failure, and a further five (24%) lost their ability to walk or needed help when walking after a mean period of 30.6 years of disease. None of the patients required mechanical ventilation. No patient required a heart transplant, one patient with NLSD-M was implanted with a cardioverter defibrillator for severe arrhythmias.

Conclusion

The genotype/phenotype correlation analysis in our population showed that the same gene mutations were associated with a varying clinical onset and course. This study highlights peculiar aspects of Italian NLSD patients that differ from those observed in Japanese patients, who were found to be affected by a marked hypertrophic cardiopathy. Owing to the varying phenotypic expression of the same mutations, it is conceivable that some additional genetic or epigenetic factors affect the symptoms and progression in this group of diseases.

Adipocyte JAK2 mediates growth hormone-induced hepatic insulin resistance

For nearly 100 years, growth hormone (GH) has been known to affect insulin sensitivity and risk of diabetes. However, the tissue governing the effects of GH signaling on insulin and glucose homeostasis remains unknown. Excess GH reduces fat mass and insulin sensitivity. Conversely, GH insensitivity (GHI) is associated with increased adiposity, augmented insulin sensitivity, and protection from diabetes. Here, we induce adipocyte-specific GHI through conditional deletion of Jak2 (JAK2A), an obligate transducer of GH signaling. Similar to whole-body GHI, JAK2A mice had increased adiposity and extreme insulin sensitivity. Loss of adipocyte Jak2 augmented hepatic insulin sensitivity and conferred resistance to diet-induced metabolic stress without overt changes in circulating fatty acids. While GH injections induced hepatic insulin resistance in control mice, the diabetogenic action was absent in JAK2A mice. Adipocyte GH signaling directly impinged on both adipose and hepatic insulin signal transduction. Collectively, our results show that adipose tissue governs the effects of GH on insulin and glucose homeostasis. Further, we show that JAK2 mediates liver insulin sensitivity via an extrahepatic, adipose tissue-dependent mechanism.

Muscle Lipid Metabolism: Role of Lipid Droplets and Perilipins

Skeletal muscle is one of the main regulators of carbohydrate and lipid metabolism in our organism, and therefore, it is highly susceptible to changes in glucose and fatty acid (FA) availability. Skeletal muscle is an extremely complex tissue: its metabolic capacity depends on the type of fibers it is made up of and the level of stimulation it undergoes, such as acute or chronic contraction. Obesity is often associated with increased FA levels, which leads to the accumulation of toxic lipid intermediates, oxidative stress, and autophagy in skeletal fibers. This lipotoxicity is one of the most common causes of insulin resistance (IR). In this scenario, the "isolation" of certain lipids in specific cell compartments, through the action of the specific lipid droplet, perilipin (PLIN) family of proteins, is conceived as a lifeguard compensatory strategy. In this review, we summarize the cellular mechanism underlying lipid mobilization and metabolism inside skeletal muscle, focusing on the function of lipid droplets, the PLIN family of proteins, and how these entities are modified in exercise, obesity, and IR conditions.