Autoantibodies to Perilipin-1 Define a Subset of Acquired Generalized Lipodystrophy

Acquired lipodystrophy is often characterized as an idiopathic subtype of lipodystrophy. Despite suspicion of an immune-mediated pathology, biomarkers such as autoantibodies are generally lacking. Here, we used an unbiased proteome-wide screening approach to identify autoantibodies to the adipocyte-specific lipid droplet protein perilipin 1 (PLIN1) in a murine model of autoimmune polyendocrine syndrome type 1 (APS1). We then tested for PLIN1 autoantibodies in human subjects with acquired lipodystrophy with two independent severe breaks in immune tolerance (including APS1) along with control subjects using a specific radioligand binding assay and indirect immunofluorescence on fat tissue. We identified autoantibodies to PLIN1 in these two cases, including the first reported case of APS1 with acquired lipodystrophy and a second patient who acquired lipodystrophy as an immune-related adverse event following cancer immunotherapy. Lastly, we also found PLIN1 autoantibodies to be specifically enriched in a subset of patients with acquired generalized lipodystrophy (17 of 46 [37%]), particularly those with panniculitis and other features of autoimmunity. These data lend additional support to new literature that suggests that PLIN1 autoantibodies represent a marker of acquired autoimmune lipodystrophies and further link them to a break in immune tolerance.

Coexistence of Colon Perforation and Congenital Lipodystrophy

Lipodystrophy (LD) is an acquired or congenital rare condition consisting of hyperlipidaemia, glucose intolerance/ insulin resistance, and almost complete absence and storage of adipose tissue. Colon perforations can be observed in type 4 congenital LD. Here, we aimed to present a case of sigmoid colon perforation which developed in a young woman with the diagnosis of LD. Extensive purulent peritonitis, significant wall thickening, and oedema in the sigmoid colon were detected during surgical exploration. Anterior resection with end colostomy procedure was then performed. Although bowel perforation has been theoretically reported to occur in LD, the presented case is the first adult patient in the literature. These individuals tend to develop colon perforation as a result of histological changes in their gastrointestinal tract. This situation should always be taken into consideration in order to avoid delay in diagnosis, especially in patients who present with abdominal pain and have a history of LD. Key Words: Intestinal perforation, Congenital lipodystrophy, Peritonitis, Sigmoid colon.

Biallelic CAV1 null variants induce congenital generalized lipodystrophy with achalasia

OBJECTIVE

CAV1 encodes caveolin-1, a major protein of plasma membrane microdomains called caveolae, involved in several signaling pathways. Caveolin-1 is also located at the adipocyte lipid droplet. Heterozygous pathogenic variants of CAV1 induce rare heterogeneous disorders including pulmonary arterial hypertension and neonatal progeroid syndrome. Only one patient was previously reported with a CAV1 homozygous pathogenic variant, associated with congenital generalized lipodystrophy (CGL3). We aimed to further delineate genetic transmission, clinical, metabolic, and cellular characteristics of CGL3.

DESIGN/METHODS

In a large consanguineous kindred referred for CGL, we performed next-generation sequencing, as well as clinical, imagery, and metabolic investigations. We studied skin fibroblasts from the index case and the previously reported patient with CGL3.

RESULTS

Four patients, aged 8 months to 18 years, carried a new homozygous p.(His79Glnfs*3) CAV1 variant. They all displayed generalized lipodystrophy since infancy, insulin resistance, low HDL-cholesterol, and/or high triglycerides, but no pulmonary hypertension. Two patients also presented at the age of 15 and 18 years with dysphagia due to achalasia, and one patient had retinitis pigmentosa. Heterozygous parents and relatives (n = 9) were asymptomatic, without any metabolic abnormality. Patients' fibroblasts showed a complete loss of caveolae and no protein expression of caveolin-1 and its caveolin-2 and cavin-1 partners. Patients' fibroblasts also displayed insulin resistance, increased oxidative stress, and premature senescence.

CONCLUSIONS

The CAV1 null variant investigated herein leads to an autosomal recessive congenital lipodystrophy syndrome. Loss of caveolin-1 and/or caveolae induces specific manifestations including achalasia which requires specific management. Overlapping phenotypic traits between the different CAV1-related diseases require further studies.

A Patient with Berardinelli-Seip Syndrome, Novel AGPAT2 Splicesite Mutation and Concomitant Development of Non-diabetic Polyneuropathy

Primary polyneuropathy in the context of Seip-Berardinelli type 1 seipinopathy, or congenital generalized lipodystrophy type 1 (CGL1) has not been previously reported. We report the case history of a 27 year old female CGL1 patient presenting with an unusual additional development of non-diabetic peripheral neuropathy and learning disabilities in early adolescence. Whole exome sequencing (WES) of the patient genome identified a novel variant, homozygous for a 52 bp intronic deletion in the AGPAT2 locus, coding for 1-acylglycerol-3-phosphate O-acyltransferase 2, which is uniquely associated with CGL1 seipinopathies, with no molecular evidence for dual diagnosis. Functional studies using RNA isolated from patient peripheral blood leucocytes showed abnormal RNA splicing resulting in the loss of 25 amino acids from the patient AGPAT2 protein coding sequence. Stability and transcription levels for the misspliced AGPAT2 mRNA in our patient nonetheless remained normal. Any AGPAT2 protein produced in our patient is therefore likely to be dysfunctional. However, formal linkage of this deletion to the neuropathy observed remains to be shown. The classical clinical presentation of a patient with AGPAT2-associated lipodystrophy shows normal cognition and no development of polyneuropathy. Cognitive disabilities and polyneuropathy are features associated exclusively with clinical CGL type 2 arising from seipin (BSCL2) gene mutations. This case study suggests that in some genetic contexts, AGPAT2 mutations can also produce phenotypes with primary polyneuropathy.

Congenital lipodystrophy induces severe osteosclerosis

Berardinelli-Seip congenital generalized lipodystrophy is associated with increased bone mass suggesting that fat tissue regulates the skeleton. Because there is little mechanistic information regarding this issue, we generated "fat-free" (FF) mice completely lacking visible visceral, subcutaneous and brown fat. Due to robust osteoblastic activity, trabecular and cortical bone volume is markedly enhanced in these animals. FF mice, like Berardinelli-Seip patients, are diabetic but normalization of glucose tolerance and significant reduction in circulating insulin fails to alter their skeletal phenotype. Importantly, the skeletal phenotype of FF mice is completely rescued by transplantation of adipocyte precursors or white or brown fat depots, indicating that adipocyte derived products regulate bone mass. Confirming such is the case, transplantation of fat derived from adiponectin and leptin double knockout mice, unlike that obtained from their WT counterparts, fails to normalize FF bone. These observations suggest a paucity of leptin and adiponectin may contribute to the increased bone mass of Berardinelli-Seip patients.

Postmortem Findings in a Young Man With Congenital Generalized Lipodystrophy, Type 4 Due to CAVIN1 Mutations

CONTEXT

Congenital generalized lipodystrophy, type 4 (CGL4) is a rare autosomal recessive disorder caused by mutations in caveolae-associated protein 1. Patients with CGL4 also have myopathy and cardiomyopathy with a predisposition for sudden death due to ventricular arrhythmias. However, the underlying pathology for these morbidities remains unknown. Therefore, we report on an autopsy of a Hispanic boy with CGL4.

CASE DESCRIPTION

Our patient had early-onset generalized lipodystrophy, feeding difficulties, myopathy, atlanto-axial dislocation, and learning disabilities. He was diagnosed with catecholaminergic polymorphic ventricular tachycardia (CPVT) at age 8 years, had poor compliance with medications, and died suddenly at age 15.3 years. Autopsy showed marked loss of subcutaneous and omental fat with no inflammatory cells in adipose tissue and normal adipocytes in the parathyroid glands. There were adipocytes interdigitating cardiac muscle fibers, with fibro-fatty infiltration in the right ventricle, near coronary sinus, and atrioventricular node. There was no evidence of coronary heart disease. The quadriceps femoris muscle did not show adipocyte infiltration, inflammation, or fibrosis. The muscularis mucosa layer was thickened in the esophagus and at the gastro-duodenal junction, and the esophagus had prominent, large nerves in the subserosa. The liver weighed 3000 g, with minimal chronic inflammation and steatosis in 40% of parenchyma, primarily in zones 2 and 3. There was no spermatogenesis in the spermatic tubules.

CONCLUSIONS

Our data suggest that fibro-fatty infiltration of the right ventricle may contribute to CPVT in patients with CGL4. Thick muscularis mucosa and large nerves in the esophagus likely contributed to dysphagia and dysmotility. A lack of spermatids suggests infertility in affected male patients.

A Novel Generalized Lipodystrophy-Associated Progeroid Syndrome Due to Recurrent Heterozygous LMNA p.T10I Mutation

BACKGROUND

Lamin A/C (LMNA) gene mutations cause a heterogeneous group of progeroid disorders, including Hutchinson-Gilford progeria syndrome, mandibuloacral dysplasia, and atypical progeroid syndrome (APS). Five of the 31 previously reported patients with APS harbored a recurrent de novo heterozygous LMNA p.T10I mutation. All five had generalized lipodystrophy, as well as similar metabolic and clinical features, suggesting a distinct progeroid syndrome.

METHODS

We report nine new patients and follow-up of two previously reported patients with the heterozygous LMNA p.T10I mutation and compare their clinical and metabolic features with other patients with APS.

RESULTS

Compared with other patients with APS, those with the heterozygous LMNA p.T10I mutation were younger in age but had increased prevalence of generalized lipodystrophy, diabetes mellitus, acanthosis nigricans, hypertriglyceridemia, and hepatomegaly, together with higher fasting serum insulin and triglyceride levels and lower serum leptin and high-density lipoprotein cholesterol levels. Prominent clinical features included mottled skin pigmentation, joint contractures, and cardiomyopathy resulting in cardiac transplants in three patients at ages 13, 33, and 47 years. Seven patients received metreleptin therapy for 0.5 to 16 years with all, except one noncompliant patient, showing marked improvement in metabolic complications.

CONCLUSIONS

Patients with the heterozygous LMNA p.T10I mutation have distinct clinical features and significantly worse metabolic complications compared with other patients with APS as well as patients with Hutchinson-Gilford progeria syndrome. We propose that they be recognized as having generalized lipodystrophy-associated progeroid syndrome. Patients with generalized lipodystrophy-associated progeroid syndrome should undergo careful multisystem assessment at onset and yearly metabolic and cardiac evaluation, as hyperglycemia, hypertriglyceridemia, hepatic steatosis, and cardiomyopathy are the major contributors to morbidity and mortality.

Clinical spectra of neuromuscular manifestations in patients with lipodystrophy: A multicenter study

Lipodystrophy is a heterogeneous group of disorders characterized by loss of adipose tissue. Here, we report on clinical spectra of neuromuscular manifestations of Turkish patients with lipodystrophy. Seventy-four patients with lipodystrophy and 20 healthy controls were included. Peripheral sensorimotor neuropathy was a common finding (67.4%) in lipodystrophic patients with diabetes. Neuropathic foot ulcers were observed in 4 patients. Drop foot developed in 1 patient with congenital generalized lipodystrophy type 1. Muscle symptoms and hypertrophy were consistent findings in congenital generalized lipodystrophy (21/21) and familial partial lipodystrophy (25/34); on the other hand, overt myopathy with elevated creatine kinase activity was a distinctive characteristic of congenital generalized lipodystrophy type 4. Muscle biopsies revealed myopathic changes at different levels. Accumulation of triglycerides was observed which contributes to insulin resistance. All patients with congenital generalized lipodystrophy suffered from tight Achilles tendons at various levels. Scoliosis was observed in congenital generalized lipodystrophy type 4 (2/2) and familial partial lipodystrophy type 2 (2/17). Atlantoaxial instability was unique to congenital generalized lipodystrophy type 4 (2/2). Bone cysts were detected in congenital generalized lipodystrophy type 1 (7/10) and congenital generalized lipodystrophy type 2 (2/8). Our study suggests that lipodystrophies are associated with a wide spectrum of neuromuscular abnormalities.

Natural History of Congenital Generalized Lipodystrophy: A Nationwide Study From Turkey

CONTEXT

Congenital generalized lipodystrophy (CGL) is a rare autosomal recessive disorder characterized by near-total lack of body fat.

OBJECTIVE

We aimed to study natural history and disease burden of various subtypes of CGL.

DESIGN

We attempted to ascertain nearly all patients with CGL in Turkey.

SETTING

This was a nationwide study.

PATIENTS OR OTHER PARTICIPANTS

Participants included 33 patients (22 families) with CGL and 30 healthy controls.

MAIN OUTCOME MEASURE(S)

We wanted to ascertain genotypes by sequencing of the known genes. Whole-body magnetic resonance imaging was used to investigate the extent of fat loss. Metabolic abnormalities and end-organ complications were measured on prospective follow-up.

RESULTS

Analysis of the AGPAT2 gene revealed four previously reported and four novel mutations (CGL1; c.144C>A, c.667_705delinsCTGCG, c.268delC, and c.316+1G>T). Analysis of the BSCL2 gene revealed four different homozygous and one compound heterozygous possible disease-causing mutations (CGL2), including four novel mutations (c.280C>T, c.631delG, c.62A>T, and c.465-468delGACT). Two homozygous PTRF mutations (c.481-482insGTGA and c.259C>T) were identified (CGL4). Patients with CGL1 had preservation of adipose tissue in the palms, soles, scalp, and orbital region, and had relatively lower serum adiponectin levels as compared to CGL2 patients. CGL4 patients had myopathy and other distinct clinical features. All patients developed various metabolic abnormalities associated with insulin resistance. Hepatic involvement was more severe in CGL2. End-organ complications were observed at young ages. Two patients died at age 62 years from cardiovascular events.

CONCLUSIONS

CGL patients from Turkey had both previously reported and novel mutations of the AGPAT2, BSCL2, and PTRF genes. Our study highlights the early onset of severe metabolic abnormalities and increased risk of end-organ complications in patients with CGL.

Progressive Generalized Lipodystrophy as a Manifestation of Autoimmune Polyglandular Syndrome Type 1

We describe APS1 in a boy with generalized lipodystrophy, oral candidiasis, autoimmune hepatitis and adrenal insufficiency. It is the first time when generalized lipodystrophy is associated with APS1.

A Frame-Shift Mutation in CAV1 Is Associated with a Severe Neonatal Progeroid and Lipodystrophy Syndrome

A 3-year-old female patient presenting with an unknown syndrome of a neonatal progeroid appearance, lipodystrophy, pulmonary hypertension, cutis marmorata, feeding disorder and failure to thrive was investigated by whole-genome sequencing. This revealed a de novo, heterozygous, frame-shift mutation in the Caveolin1 gene (CAV1) (p.Phe160X). Mutations in CAV1, encoding the main component of the caveolae in plasma membranes, cause Berardinelli-Seip congenital lipodystrophy type 3 (BSCL). Although BSCL is recessive, heterozygous carriers either show a reduced phenotype of partial lipodystrophy, pulmonary hypertension, or no phenotype. To investigate the pathogenic mechanisms underlying this syndrome in more depth, we performed next generation RNA sequencing of peripheral blood, which showed several dysregulated pathways in the patient that might be related to the phenotypic progeroid features (apoptosis, DNA repair/replication, mitochondrial). Secondly, we found a significant down-regulation of known Cav1 interaction partners, verifying the dysfunction of CAV1. Other known progeroid genes and lipodystrophy genes were also dysregulated. Next, western blotting of lysates of cultured fibroblasts showed that the patient shows a significantly decreased expression of wild-type CAV1 protein, demonstrating a loss-of-function mutation, though her phenotype is more severe that other heterozygotes with similar mutations. This phenotypic variety could be explained by differences in genetic background. Indications for this are supported by additional rare variants we found in AGPAT2 and LPIN1 lipodystrophy genes. CAV1, AGPAT2 and LPIN1 all play an important role in triacylglycerol (TAG) biosynthesis in adipose tissue, and the defective function in different parts of this pathway, though not all to the same extend, could contribute to a more severe lipoatrophic phenotype in this patient. In conclusion, we report, for the first time, an association of CAV1 dysfunction with a syndrome of severe premature aging and lipodystrophy. This may contribute to a better understanding of the aging process and pathogenic mechanisms that contribute to premature aging.

Alterations in lipid signaling underlie lipodystrophy secondary to AGPAT2 mutations

Congenital generalized lipodystrophy (CGL), secondary to AGPAT2 mutation is characterized by the absence of adipocytes and development of severe insulin resistance. In the current study, we investigated the adipogenic defect associated with AGPAT2 mutations. Adipogenesis was studied in muscle-derived multipotent cells (MDMCs) isolated from vastus lateralis biopsies obtained from controls and subjects harboring AGPAT2 mutations and in 3T3-L1 preadipocytes after knockdown or overexpression of AGPAT2. We demonstrate an adipogenic defect using MDMCs from control and CGL human subjects with mutated AGPAT2. This defect was rescued in CGL MDMCs with a retrovirus expressing AGPAT2. Both CGL-derived MDMCs and 3T3-L1 cells with knockdown of AGPAT2 demonstrated an increase in cell death after induction of adipogenesis. Lack of AGPAT2 activity reduces Akt activation, and overexpression of constitutively active Akt can partially restore lipogenesis. AGPAT2 modulated the levels of phosphatidic acid, lysophosphatidic acid, phosphatidylinositol species, as well as the peroxisome proliferator-activated receptor γ (PPARγ) inhibitor cyclic phosphatidic acid. The PPARγ agonist pioglitazone partially rescued the adipogenic defect in CGL cells. We conclude that AGPAT2 regulates adipogenesis through the modulation of the lipome, altering normal activation of phosphatidylinositol 3-kinase (PI3K)/Akt and PPARγ pathways in the early stages of adipogenesis.

Fatal cardiac arrhythmia and long-QT syndrome in a new form of congenital generalized lipodystrophy with muscle rippling (CGL4) due to PTRF-CAVIN mutations

We investigated eight families with a novel subtype of congenital generalized lipodystrophy (CGL4) of whom five members had died from sudden cardiac death during their teenage years. ECG studies revealed features of long-QT syndrome, bradycardia, as well as supraventricular and ventricular tachycardias. Further symptoms comprised myopathy with muscle rippling, skeletal as well as smooth-muscle hypertrophy, leading to impaired gastrointestinal motility and hypertrophic pyloric stenosis in some children. Additionally, we found impaired bone formation with osteopenia, osteoporosis, and atlanto-axial instability. Homozygosity mapping located the gene within 2 Mbp on chromosome 17. Prioritization of 74 candidate genes with GeneDistiller for high expression in muscle and adipocytes suggested PTRF-CAVIN (Polymerase I and transcript release factor/Cavin) as the most probable candidate leading to the detection of homozygous mutations (c.160delG, c.362dupT). PTRF-CAVIN is essential for caveolae biogenesis. These cholesterol-rich plasmalemmal vesicles are involved in signal-transduction and vesicular trafficking and reside primarily on adipocytes, myocytes, and osteoblasts. Absence of PTRF-CAVIN did not influence abundance of its binding partner caveolin-1 and caveolin-3. In patient fibroblasts, however, caveolin-1 failed to localize toward the cell surface and electron microscopy revealed reduction of caveolae to less than 3%. Transfection of full-length PTRF-CAVIN reestablished the presence of caveolae. The loss of caveolae was confirmed by Atomic Force Microscopy (AFM) in combination with fluorescent imaging. PTRF-CAVIN deficiency thus presents the phenotypic spectrum caused by a quintessential lack of functional caveolae.

Patients with generalized lipodystrophy have a marked lack of body fat. Several gene defects have been described that impede fat synthesis and maturation of fat cells. Here we report on mutations in a novel gene, called PTRF-CAVIN, causing congenital generalized lipodystrophy type 4 (CGL4) that is additionally associated with muscle disease. Patients' muscles are large but weak and show an involuntary, rolling contraction pattern called “rippling.” Further symptoms comprise life-threatening cardiac arrhythmias and a disorder of bone formation. We searched for shared segments in the genome of seven patients and found the responsible gene, called PTRF-CAVIN, on chromosome 17. This gene is crucial for caveolae (latin for “small caves”) formation. These small indentations of the cell membrane are found on the surface of muscle, bone, fat, and immune cells and facilitate cell-to-cell communication and the absorption of substances from the extracellular space. Patients lack more than 97% of caveolae and artificial insertion of the correct gene into patient skin cells led to the reappearance of caveolae. As cardiac arrhythmia is a severe and potentially life-threatening condition, patients with CGL4 should be closely monitored by ECG and, if necessary, fitted with an implanted pacemaker and cardioverter defibrillator (ICD) device.

Berardinelli syndrome. A case report with fatal outcome

The aim of this paper is to present the main clinical findings and evolution of a fatal case of Berardinelli Syndrome (congenital generalized lipodystrophy). A 15-year-old girl, followed since the age of three months in the Genetic outpatients' clinic, developed insulin resistance when she was eight years old. She had hyperchloremic metabolic acidosis, bilateral retinopathy, proteinuria and hydronephrosis. She was hospitalized several times due to urinary infections. In her last admission she had fever, abdominal pain and was diagnosed urinary sepsis. She presented hemodynamic instability and died, despite all therapeutic measures adopted. Considering the rarity of this syndrome it is important to describe the clinical presentation and evolution of this patient with Berardinelli Syndrome, which developed renal dysfunction and had a fatal outcome.