Analysis of disease characteristics of a large patient cohort with congenital generalized lipodystrophy from the Middle East and North Africa

BACKGROUND

Congenital generalized lipodystrophy (CGL) is a rare inherited disease characterized by a near-total absence of adipose tissue and is associated with organ system abnormalities and severe metabolic complications. Here, we have analyzed the disease characteristics of the largest CGL cohort from the Middle East and North Africa (MENA) who have not received lipodystrophy-specific treatment.

METHODS

CGL was diagnosed clinically by treating physicians through physical assessment and supported by genetic analysis, fat loss patterns, family history, and the presence of parental consanguinity. Data were obtained at the time of patient diagnosis and during leptin-replacement naïve follow-up visits as permitted by available medical records.

RESULTS

Data from 43 patients with CGL (37 females, 86%) were collected from centers located in eight countries. The mean (median, range) age at diagnosis was 5.1 (1.0, at birth-37) years. Genetic analysis of the overall cohort showed that CGL1 (n = 14, 33%) and CGL2 (n = 18, 42%) were the predominant CGL subtypes followed by CGL4 (n = 10, 23%); a genetic diagnosis was unavailable for one patient (2%). There was a high prevalence of parental consanguinity (93%) and family history (67%) of lipodystrophy, with 64% (n = 25/39) and 51% (n = 20/39) of patients presenting with acromegaloid features and acanthosis nigricans, respectively. Eighty-one percent (n = 35/43) of patients had at least one organ abnormality; the most frequently affected organs were the liver (70%, n = 30/43), the cardiovascular system (37%, n = 16/43) and the spleen (33%, n = 14/43). Thirteen out of 28 (46%) patients had HbA1c > 5.7% and 20/33 (61%) had triglyceride levels > 2.26 mmol/L (200 mg/dl). Generally, patients diagnosed in adolescence or later had a greater severity of metabolic disease versus those diagnosed during childhood; however, metabolic and organ system abnormalities were observed in a subset of patients diagnosed before or at 1 year of age.

CONCLUSIONS

This analysis suggests that in addition to the early onset of fat loss, family history and high consanguinity enable the identification of young patients with CGL in the MENA region. In patients with CGL who have not received lipodystrophy-specific treatment, severe metabolic disease and organ abnormalities can develop by late childhood and worsen with age.

Plasma signatures of Congenital Generalized Lipodystrophy patients identified by untargeted lipidomic profiling are not changed after a fat-containing breakfast meal

BACKGROUND

The incapacity to store lipids in adipose tissue in Congenital Generalized Lipodystrophy (CGL) causes hypoleptinemia, increased appetite, ectopic fat deposition and lipotoxicity. CGL patients experience shortened life expectancy. The plasma lipidomic profile has not been characterized fully in CGL, nor has the extent of dietary intake in its modulation. The present work investigated the plasma lipidomic profile of CGL patients in comparison to eutrophic individuals at the fasted state and after a breakfast meal.

METHOD

Blood samples from 11 CGL patients and 10 eutrophic controls were collected after 12 h fasting (T0) and 90 min after an ad libitum fat-containing breakfast (T90). The lipidomic profile of extracted plasma lipids was characterized by non-target liquid chromatography mass spectrometry.

RESULTS

Important differences between groups were observed at T0 and at T90. Several molecular species of fatty acyls, glycerolipids, sphingolipids and glycerophospholipids were altered in CGL. All the detected fatty acyl molecular species, several diacylglycerols and one triacylglycerol species were upregulated in CGL. Among sphingolipids, one sphingomyelin and one glycosphingolipid species showed downregulation in CGL. Alterations in the glycerophospholipids glycerophosphoethanolamines, glycerophosphoserines and cardiolipins were more complex. Interestingly, when comparing T90 versus T0, the lipidomic profile in CGL did not change as intensely as it did for control participants.

CONCLUSIONS

The present study found profound alterations in the plasma lipidomic profile of complex lipids in CGL patients as compared to control subjects. A fat-containing breakfast meal did not appear to significantly influence the CGL profile observed in the fasted state. Our study may have implications for clinical practice, also aiding to a deeper comprehension of the role of complex lipids in CGL in view of novel therapeutic strategies.

Metreleptin Treatment in a Boy with Congenital Generalized Lipodystrophy due to Homozygous c.465_468delGACT (p.T156Rfs*8) Mutation in the BSCL2 Gene: Results From the First-year

Congenital generalized lipodystrophy (CGL) is a rare, autosomal recessive disorder characterized by an almost complete absence of body fat. In CGL, patients may have hyperphagia due to leptin deficiency. Recombinant human leptin (metreleptin) has been suggested as an effective treatment option. We present successful treatment with metreleptin in a boy with CGL and results from the first year of follow-up. An eight-month-old boy presented with excessive hair growth and a muscular appearance. On examination he had hypertrichosis, decreased subcutaneous adipose tissue over the whole body and hepatomegaly. Laboratory investigations revealed hypertriglyceridemia, hyperinsulinemia, elevated liver transaminases and low leptin levels. Molecular genetic analysis detected a homozygous, c.465_468delGACT (p.T156Rfs*8) mutation in the BSCL2 gene. A diagnosis of CGL type 2 was considered. Despite dietary intervention, exercise, and treatment with additional omega-3 and metformin, the hypertriglyceridemia, hyperinsulinemia, and elevated liver transaminase levels worsened. Metreleptin treatment was started and after one year hyperphagia had disappeared, and there was dramatic improvement in levels of insulin, hemoglobin A1c, triglycerides and liver transaminases. Hepatosteatosis was lessened and hepatosplenomegaly was much improved. Metreleptin appears to be an effective treatment option in children with CGL that remarkably improved metabolic complications in the presented case. Initiation of metreleptin treatment in the early period may decrease mortality and morbidity, and increase the quality of life in children with CGL.

Lipodystrophy for the Diabetologist-What to Look For

PURPOSE OF REVIEW

Genetic or acquired lipodystrophies are characterized by selective loss of body fat along with predisposition towards metabolic complications of insulin resistance, such as diabetes mellitus, hypertriglyceridemia, hepatic steatosis, polycystic ovarian syndrome, and acanthosis nigricans. In this review, we discuss the various subtypes and when to suspect and how to diagnose lipodystrophy.

RECENT FINDINGS

The four major subtypes are autosomal recessive, congenital generalized lipodystrophy (CGL); acquired generalized lipodystrophy (AGL), mostly an autoimmune disorder; autosomal dominant or recessive familial partial lipodystrophy (FPLD); and acquired partial lipodystrophy (APL), an autoimmune disorder. Diagnosis of lipodystrophy is mainly based upon physical examination findings of loss of body fat and can be supported by body composition analysis by skinfold measurements, dual-energy x-ray absorptiometry, and whole-body magnetic resonance imaging. Confirmatory genetic testing is helpful in the proband and at-risk family members with suspected genetic lipodystrophies. The treatment is directed towards the specific comorbidities and metabolic complications, and there is no treatment to reverse body fat loss. Metreleptin should be considered as the first-line therapy for metabolic complications in patients with generalized lipodystrophy and for prevention of comorbidities in children. Metformin and insulin therapy are the best options for treating hyperglycemia and fibrates and/or fish oil for hypertriglyceridemia. Lipodystrophy should be suspected in lean and muscular subjects presenting with diabetes mellitus, hypertriglyceridemia, non-alcoholic fatty liver disease, polycystic ovarian syndrome, or amenorrhea. Diabetologists should be aware of lipodystrophies and consider genetic varieties as an important subtype of monogenic diabetes.

The neonatal onset diabetes mellitus of Chinese neonate with congenital generalized lipodystrophy 2: a case report

BACKGROUND

Congenital generalized lipodystrophy (CGL) is a clinically heterogeneous disorder characterized by near total absence of adipose tissue along with metabolic complications. Diabetes mellitus developed from CGL usually present between ages 15 and 20 years, and there are few reports in neonate.

CASE PRESENTATION

In this report, we described a rare clinical presentation of CGL in a 12-day-old Chinese female neonates with hyperglycemia, hyperlipidemia, and subsequently appeared diabetes, hepatomegaly and fatty liver. The two clinical-exome sequencing identified heterozygous null mutations (c.793C > T and c.565G > T) in BSCL2 gene which was inherited from father and mother respectively. To date, it was the firstly reported CGL patient with neonatal onset diabetes. The neonate was treated with antibiotic, insulin and deeply hydrolyzed formula milk to significantly decrease FBG and serum trigylcerides levels.  CONCLUSIONS: Our case report analyzes the causes of early onset diabetes may relate with the locus of BSCL2 gene mutations and infection induction. It also suggests the importance of early identification, genetic analysis, and symptomatic treatment in the CGL, which are essential for improving the prognosis of children.

Generalized lipoatrophy syndromes

Generalized lipodystrophy (GL) syndromes are a group of rare heterogenous disorders, characterized by total subcutaneous fat loss. The frequency of GL is currently assessed as approximately 0,23 cases per million of the population, in Europe - as 0,96 cases per million of the population. They can be congenital (CGL) or acquired (AGL) depending on the etiology and the time of the onset of fat loss. Both CGL and AGL are often associated with different metabolic complications, such as hypertriglyceridemia, insulin resistance and lipoatrophic diabetes mellitus, metabolically associated FLD, arterial hypertension, proteinuria, reproductive system disorders. In this review we aimed to summarize the information on all forms of generalized lipodystrophy, especially the ones of genetic etiology, their clinical manifestations and complications, the perspectives for diagnostics, treatment and further research.

SARS-COV-2 infection outcomes in patients with congenital generalized lipodystrophy

BACKGROUND

A new strain of human coronavirus (HCoV) spread rapidly around the world. Diabetes and obesity are associated with a worse prognosis in these patients. Congenital Generalized Lipodystrophy (CGL) patients generally have poorly controlled diabetes and require extremely high doses of insulin. There is no documentation in the literature of cases of COVID in CGL patients. Thus, we aimed to evaluate the prevalence of SARS-CoV-2 infection in CGL patients, and the association of their clinical and metabolic characteristics and outcomes.

METHODS

This is a cross-sectional study carried out between July and October 2020. Clinical data collected were respiratory or other flu-like symptoms, need of hospitalization in the last three months, CGL comorbidities, and medications in use. Cholesterol, triglycerides, glycohemoglobin A1c levels, anti-SARS-CoV-2 antibodies and nasopharyngeal swab for RT-qPCR were also obtained in all CGL patients. Mann-Whitney U test was used to analyze the characteristics of the participants, verifying the non-adherence of the data to the Gaussian distribution. In investigating the association between categorical variables, we used Pearson's chi-square test and Fisher's exact test. A significance level of 5% was adopted.

RESULTS

Twenty-two CGL patients were assessed. Eight subjects (36.4%) had reactive anti-SARS-CoV-2 antibodies. Only one of these, also presented detectable RT-qPCR. Five individuals (62.5%) were women, median age of 13.5 years (1 to 37). Symptoms like fever, malaise, nausea, diarrhea and chest pain were present, and all asymptomatic patients were children. All subjects had inadequate metabolic control, with no difference between groups. Among positive individuals there was no difference between those with AGPAT2 (75%) and BSCL2 gene mutations (25%) (p > 0.05). No patient needed hospitalization or died.

CONCLUSIONS

We described a high prevalence of SARS-CoV-2 infection in CGL patients with a good outcome in all of them. These findings suggest that at least young CGL patients infected by SARS-COV-2 are not at higher risk of poor outcome, despite known severe metabolic comorbidities.

Targeted massively parallel sequencing for congenital generalized lipodystrophy

Objective

Our aim is to establish genetic diagnosis of congenital generalized lipodystrophy (CGL) using targeted massively parallel sequencing (MPS), also known as next-generation sequencing (NGS).

Methods

Nine unrelated individuals with a clinical diagnosis of CGL were recruited. We used a customized panel to capture genes related to genetic lipodystrophies. DNA libraries were generated, sequenced using the Illumina MiSeq, and bioinformatics analysis was performed.

Results

An accurate genetic diagnosis was stated for all nine patients. Four had pathogenic variants in AGPAT2 and three in BSCL2. Three large homozygous deletions in AGPAT2 were identified by copy-number variant analysis.

Conclusion

Although we have found allelic variants in only 2 genes related to CGL, the panel was able to identify different variants including deletions that would have been missed by Sanger sequencing. We believe that MPS is a valuable tool for the genetic diagnosis of multi-genes related diseases, including CGL.

Leu124Serfs*26, a novel AGPAT2 mutation in congenital generalized lipodystrophy with early cardiovascular complications

BACKGROUND

Congenital generalized lipodystrophy (CGL) is a rare autosomal recessive disorder characterized by the near-total loss of subcutaneous adipose tissue soon after birth, resulting in ectopic fat deposition and severe metabolic disturbances. Most cases are caused by AGPAT2 or BSCL2 gene mutations. We aimed to report two unrelated CGL patients with a novel frameshift mutation in AGPAT2 (p.Leu124Serfs*26).

METHODS

Clinical features and laboratory were obtained by medical interview and medical records review. DNA was extracted, amplified and sequenced. Mutation Taster was used to estimate the potential biological impact of the AGPAT2 mutations on the protein function.

RESULTS

Patient 1: a 30-year-old woman with lipodystrophy phenotype at birth and diagnosis of diabetes at age 13 presented with severe hypertriglyceridemia and pancreatitis at age 17, hypertension and albuminuria at age 18, proliferative diabetic retinopathy with visual loss at age 25, and an acute myocardial infarction due to multivessel coronary disease during a hospitalization for forefoot amputation at age 29. At this time, she required hemodialysis due to end-stage renal disease. Patient 2: a 12-year-old girl with lipodystrophy phenotype and hypertriglyceridemia detected in the first year of life and abnormalities in the global longitudinal strain, evaluated by speckle-tracking echocardiography last year. Molecular analysis identified a c.369_372delGCTC (p.Leu124Serfs*26) AGPAT2 mutation in both unrelated patients, a compound heterozygous mutation in Patient 1, and homozygous mutation in Patient 2.

CONCLUSION

We describe two unrelated patients with type 1 CGL due to Leu124Serfs*26, a novel AGPAT2 frameshift mutation, presenting as early cardiovascular disease. These findings suggest an association between Leu124Serfs*26 and a more aggressive phenotype.

Seipin-linked congenital generalized lipodystrophy type 2: a rare case with multiple lytic and pseudo-osteopoikilosis lesions

Congenital generalized lipodystrophy (CGL), or Berardinelli-Seip syndrome (BSCL), is a part of lipodystrophic syndromes that constitute a heterogeneous group of genetic or acquired generalized or partial body fat loss disorders. It is a rare autosomal recessive disease characterized by a near-absence of adipose tissue from birth or early infancy and severe insulin resistance. CGL is classified as type 1-4, depending on the gene involved, and bone lytic lesion is found frequently in type 1 especially in long bones, but reported to be rare in type 2. Here we report an active lifestyle 25-year-old woman with type 2 CGL showing multiple bone lytic and pseudo-osteopoikilosis lesions in hands and feet. Radiograph bone survey showed no apparent abnormality in pelvic bone or axial skeletons. Bone marrow was completely absent and extra-skeletal general fat loss was also evident in whole-body magnetic resonance imaging sparing the orbital, axial, sole, and palmar regions. Radiographic bone survey is important even for type 2 CGL to find the change of bones to provide direction of preventing excessive overload or activity.

Congenital generalized lipodystrophy: The evaluation of clinical follow-up findings in a series of five patients with type 1 and two patients with type 4

Congenital generalized lipodystrophy (CGL) is a rare disorder characterized by lipoatrophy affecting the face, limbs and trunk, acromegaloid features, hepatomegaly, hypertriglyceridemia, and insulin resistance. The aim of this study is to evaluate the long-term follow-up findings including gastrointestinal and cardiac manifestations of the patients with CGL1 and CGL4, caused by mutations in the AGPAT2 and CAVIN1 genes, respectively. Two patients aged 2 and 9 years with the same biallelic CAVIN1 mutation and five patients aged between 6 months and 11 years 4 months with AGPAT2 mutations have been followed up for 3-9 years. The patients were between 7 and 20 years of age at their last examination. One of the two patients with CGL4 had congenital pyloric stenosis. The other patient with CGL4 have developed recurrent duodenal perforations which have not been reported in CGL patients previously. The pathological examination of duodenal specimens revealed increased subserosal fibrous tissue and absent submucosal adipose tissue. None of the five CGL1 patients had gastrointestinal problems. Two patients with CGL4 developed hypertrophic cardiomyopathy (HCMP) and severe cardiac arrhythmia, only one patient with CGL1 had HCMP. Hyperinsulinemia was detected in one patient with CGL4 and three patients with CGL1, these three CGL1 patients also had acanthosis nigricans. Hepatic steatosis was detected in one patient with CGL4 and two patients with CGL1 by ultrasonography. In conclusion, these findings suggest that CGL4 patients should also be carefully followed up for gastrointestinal and cardiac manifestations.

Celia's encephalopathy and c.974dupG in BSCL2 gene: a hidden change in a known variant

Celia's encephalopathy (progressive encephalopathy with/without lipodystrophy (PELD)) is a childhood neurodegenerative disorder with a fatal prognosis before the age of 10, due to the variant c.985C>T in the BSCL2 gene that causes a cryptic splicing site leading to skipping of exon 7. For years, different authors have reported cases of congenital generalized lipodystrophy due to the variant c.974dupG in BSCL2 associated with neurological manifestations of variable severity, although some of them clearly superimposable to PELD. To identify the molecular mechanisms responsible for these neurological alterations in two patients with c.974dupG. Clinical characterization, biochemistry, and neuroimaging studies of two girls carrying this variant. In silico analysis, PCR amplification, and BSCL2 cDNA sequencing. BSCL2-201 transcript expression, which lacks exon 7, by qPCR in fibroblasts from the index case, from a healthy child as a control and from two patients with PELD, and in leukocytes from the index case and her parents. One with a severe encephalopathy including a picture of intellectual deficiency, severe language impairment, myoclonic epilepsy, and lipodystrophy as described in PELD, dying at 9 years and 9 months of age. The other 2-year-old patient showed incipient signs of neurological involvement. In silico and cDNA sequencing studies showed that variant c.974dupG gives rise to skipping of exon 7. The expression of BSCL2-201 in fibroblasts was significantly higher in the index case than in the healthy child, although less than in the case with homozygous PELD due to c.985C>T variant. The expression of this transcript was approximately half in the healthy carrier parents of this patient. The c.974dupG variant leads to the skipping of exon 7 of the BSCL2 gene and is responsible for a variant of Celia's encephalopathy, with variable phenotypic expression.

Monogenic forms of lipodystrophic syndromes: diagnosis, detection, and practical management considerations from clinical cases

BACKGROUND

Lipodystrophic syndromes are rare diseases of genetic or acquired origin characterized by partial or generalized lack of body fat. Early detection and diagnosis are crucial to prevent and manage associated metabolic dysfunctions, i.e. insulin resistance, dyslipidemia, fatty liver, and diabetes, and to provide appropriate genetic counseling. By means of several representative case studies, this article illustrates the diagnostic and management challenges of lipodystrophic syndromes.

REVIEW

Berardinelli-Seip congenital lipodystrophy (BSCL) is typically diagnosed at birth, or soon thereafter, with generalized lipoatrophy and hepatomegaly secondary to hepatic steatosis. Physicians must also consider this diagnosis in adults with atypical non-autoimmune diabetes, hypertriglyceridemia, and a lean and muscular phenotype. The BSCL1 subtype due to mutations in the AGPAT2 gene can have an unusual presentation, especially in neonates and infants. Particular attention should be paid to infants presenting failure to thrive who also have hepatomegaly and metabolic derangements. The BSCL2 sub-type due to mutations in the BSCL gene tends to be more severe than BSCL1, and is characterized by greater fat loss, mild intellectual disability, earlier onset of diabetes, and higher incidence of premature death. Effective management from an earlier age may moderate the natural disease course. Partial lipodystrophies may easily be confused with common central obesity and/or metabolic syndrome. In patients with unexplained pancreatitis and hypertriglyceridemia, lipodystrophies such as familial partial lipodystrophy type 2 (FPLD2; Dunnigan type, due to LMNA mutations) should be considered. Oral combined contraceptives, which can reveal the disease by inducing severe hypertriglyceridemia, are contraindicated. Endogenous estrogens may also lead to "unmasking" of the FPLD2 phenotype, which often appears at puberty, and is more severe in females than males.

CONCLUSIONS

Diet and exercise, adapted to age and potential comorbidities, are essential prerequisites for therapeutic management of lipodystrophic syndromes. Metreleptin therapy can be useful to manage lipodystrophy-related metabolic complications.

Association between cardiovascular autonomic neuropathy and left ventricular hypertrophy in young patients with congenital generalized lipodystrophy

BACKGROUND

Congenital generalized lipodystrophy (CGL) is a rare disorder characterized by the absence of subcutaneous adipose tissue, severe insulin resistance, diabetes mellitus, and cardiovascular complications, including cardiac autonomic neuropathy (CAN), left ventricular hypertrophy (LVH), and atherosclerosis. The present study aimed to access the association between CAN parameters and cardiovascular abnormalities in CGL patients.

METHODS

A cross-sectional study was conducted with 10 CGL patients and 20 healthy controls matched for age, sex, BMI, and pubertal stage. We evaluated clinical, laboratory, and cardiovascular parameters-left ventricular mass index (LVMI), interventricular septum thickness (IVS), systolic and diastolic function determined by two-dimensional transthoracic echocardiography; carotid intimal media thickness (cIMT); and cQT interval. Heart rate variability (HRV) was evaluated by spectral analysis components-high frequency (HF), low frequency (LF), very low frequency (VLF), LF/HF ratio, and total amplitude spectrum (TAS)-and cardiovascular reflexes tests (postural hypotension test, respiratory, orthostatic and Valsalva coefficients).

RESULTS

In CGL group, four patients (40%) had LVH and diastolic dysfunction. HF component (parasympathetic control) was lower in LVH patients. CGL patients presented higher values of cIMT and cQT interval than heathy subjects. Inverse association between LVMI and LF (p = 0.011), IVS and LF (p = 0.007), and cIMT and leptin (p < 0.001) were observed, even after adjustments by HOMA-IR, A1c, and blood pressure. In CGL group, there were associations between LMVI and HF component (IC95%: - 1.000; - 00.553), LVMI and TAS (IC95%: - 1.000; - 0.012), and IVS and HF component (IC95%: - 1.000; - 0.371).

CONCLUSION

The association between increased LV mass and parameters of HRV provides possible speculations about the involvement of CAN in the pathophysiology of the cardiac complications, including LVH, in patients with CGL.

Further delineation of AGPAT2 and BSCL2 related congenital generalized lipodystrophy in young infants

BACKGROUND AND OBJECTIVES

Congenital generalized lipodystrophy (CGL) is a rare autosomal recessive disorder with two major subtypes, which are caused by AGPAT2 and BSCL2 mutations. Our aim was to further investigate the genetic features and clinical characteristics of infant patients with CGL.

PATIENTS AND METHODS

Three male infants and two female infants aged from one month to three months and unrelated with each other were involved in this study. Both whole-exome and Sanger sequencing were conducted, and variants were compared with in-house and public databases.

RESULTS

The five infants with CGL displayed generalized lipodystrophy, skeletal muscle hypertrophy, hepatomegaly, hypertriglyceridemia, hyperinsulinemia, and liver dysfunction. Four patients (#2-5) showed more severe hypertriglyceridemia than Patient #1. A compound heterozygosity for novel frameshift mutations c.622_626delTCCTC and c.513delC in AGPAT2 was identified in Patient #1. Seven mutations in BSCL2 were found among Patients #2-5, in which splice site mutation c.404+1G > T, nonsense mutation c.402C > G, and frameshift mutation c.759_760delGA were novel. After medical treatment, metabolic parameters for all patients were under control. At the time of writing, they are seven to seventeen months old with much improved physical and cognitive development.

CONCLUSIONS

Two novel mutations in AGPAT2 and three novel mutations in BSCL2 were identified from five unrelated infant patients diagnosed with CGL1 and CGL2.

Lipodystrophy Syndromes

Lipodystrophies are heterogeneous disorders characterized by varying degrees of body fat loss and predisposition to insulin resistance and its metabolic complications. They are subclassified depending on degree of fat loss and whether the disorder is genetic or acquired. The two most common genetic varieties include congenital generalized lipodystrophy and familial partial lipodystrophy; the two most common acquired varieties include acquired generalized lipodystrophy and acquired partial lipodystrophy. Highly active antiretroviral therapy-induced lipodystrophy in patients infected with human immunodeficiency virus and drug-induced localized lipodystrophy are common subtypes. The metabolic abnormalities associated with lipodystrophy include insulin resistance, hypertriglyceridemia, and hepatic steatosis. Management focuses on preventing and treating metabolic complications.

Impaired adipogenic capacity in induced pluripotent stem cells from lipodystrophic patients with BSCL2 mutations

OBJECTIVE

Congenital generalized lipodystrophy (CGL) is an autosomal recessive disorder characterized by marked scarcity of adipose tissue, extreme insulin resistance, hypertriglyceridemia, hepatic steatosis and early-onset diabetes. Mutation of the BSCL2/SEIPIN gene causes the most severe form of CGL. The aim of this study was to generate induced pluripotent stem (iPS) cells from patients with CGL harboring BSCL2/SEIPIN mutations.

METHODS

Skin biopsies were obtained from two Japanese patients with CGL harboring different nonsense mutations (E189X and R275X) in BSCL2/SEIPIN. The fibroblasts thus obtained were infected with retroviruses encoding OCT4, SOX2, c-MYC, and KLF4. The generated iPS cells were evaluated for pluripotency by examining the expression of pluripotency markers (alkaline phosphatase, SSEA-4, TRA-1-60, and NANOG) and their ability to differentiate to three germ layers in vitro by forming embryoid bodies, and to form teratomas in vivo. Adipogenic capacity of differentiated BSCL2-iPS cells was determined by oil red O and adipose differentiation-related protein (ADRP) staining. Rescue experiments were also performed using stable expression of wild-type BSCL2. A coimmunoprecipitation assay was conducted to investigate the interaction of SEIPIN with ADRP.

RESULTS

iPS cells were generated from fibroblasts of the two patients with CGL. Each of the patient-derived iPS (BSCL2-iPS) clones showed all of the hallmarks of pluripotency and could differentiate into derivatives of all three germ layers in vitro by forming embryoid bodies, and form teratomas after injection into mouse testes. BSCL2-iPS cells maintained the mutations in BSCL2 and lacked intact BSCL2. Upon adipogenic differentiation, BSCL2-iPS cells exhibited marked reduction of lipid droplet formation concomitant with diffuse cytoplasmic distribution of ADRP, compared with iPS cells from healthy individuals. Forced expression of BSCL2 not only rescued the lipid accumulation defects, but also restored cytoplasmic punctate localization of ADRP in BSCL2-iPS cells. Coimmunoprecipitation indicated SEIPIN interacted with ADRP.

CONCLUSION

BSCL2-iPS cells that recapitulate the lipodystrophic phenotypes in vitro could provide valuable models with which to study the physiology of lipid accumulation and the pathology of human lipodystrophy. We found that BSCL2 defines the localization of ADRP, which has a role in lipid accumulation and adipogenic differentiation.

Diet rich in Docosahexaenoic Acid/Eicosapentaenoic Acid robustly ameliorates hepatic steatosis and insulin resistance in seipin deficient lipodystrophy mice

BACKGROUND

N-3 polyunsaturated fatty acids (n-3 PUFAs), in particular eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have been shown to effectively improve hepatic steatosis and insulin resistance caused by obesity. Lipodystrophy could also develop insulin resistance and hepatic steatosis. However, the effect of supplemental DHA/EPA to hepatic steatosis caused by lipodystrophy is unknown. In this study, we investigated whether a diet rich in n-3 PUFAs could ameliorate severe steatosis in lipoatrophic seipin gene knockout (SKO) mice.

METHODS

Eight-week-old C57BL/6 J WT and SKO mice were fed with normal chow diet (NC), or 2 % DHA/EPA (3:1) diet for 12 weeks. Total cholesterol (TC) and triglycerides (TG) in plasma and liver, plasma high density lipoprotein-cholesterol (HDL-C), glucose (Glu), insulin, leptin and adiponectin levels were measured. Gene regulations and protein levels were investigated using quantitative PCR and western blot in liver.

RESULTS

We found that the DHA/EPA diet protected against hepatic steatosis effectively in SKO mice morphologically. Hepatic TG content was decreased about 40 % (p < 0.05) in SKO mice fed with the DHA/EPA diet compared to chow fed SKO controls. Glucose and insulin tolerance were also improved significantly in SKO mice with DHA/EPA diet. In analyzing hepatic gene expression pattern it was found that TG synthesis related genes, such as carbohydrate response element binding protein (ChREBP), stearoyl-CoA desaturase 1 (SCD1) and fatty acid synthase (Fas) were upregulated in SKO mice compared to WT mice but were significantly decreased in SKO mice on DHA/EPA diet. Fatty acid β-oxidation related genes, on the other hand, such as peroxisome proliferator-activated receptor α (PPARα), carnitine palmitoyltransferase (CPT) and acyl-CoA oxidase 1 (ACOX1) were elevated in both WT and SKO groups on DHA/EPA diets. The protein levels of PPARα, SCD1, CPT1α, Insulin receptor substrate 1 (IRS1) and ratio of p-AKT to AKT showed the same tendency as the result of genes expressions.

CONCLUSIONS

The results suggest that n-3 PUFAs rich diet ameliorates lipodystrophy-induced hepatic steatosis through reducing TG synthesis, improving insulin resistance and enhancing β-oxidation in SKO mice.

Diet rich in Docosahexaenoic Acid/Eicosapentaenoic Acid robustly ameliorates hepatic steatosis and insulin resistance in seipin deficient lipodystrophy mice

BACKGROUND

N-3 polyunsaturated fatty acids (n-3 PUFAs), in particular eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have been shown to effectively improve hepatic steatosis and insulin resistance caused by obesity. Lipodystrophy could also develop insulin resistance and hepatic steatosis. However, the effect of supplemental DHA/EPA to hepatic steatosis caused by lipodystrophy is unknown. In this study, we investigated whether a diet rich in n-3 PUFAs could ameliorate severe steatosis in lipoatrophic seipin gene knockout (SKO) mice.

METHODS

Eight-week-old C57BL/6 J WT and SKO mice were fed with normal chow diet (NC), or 2 % DHA/EPA (3:1) diet for 12 weeks. Total cholesterol (TC) and triglycerides (TG) in plasma and liver, plasma high density lipoprotein-cholesterol (HDL-C), glucose (Glu), insulin, leptin and adiponectin levels were measured. Gene regulations and protein levels were investigated using quantitative PCR and western blot in liver.

RESULTS

We found that the DHA/EPA diet protected against hepatic steatosis effectively in SKO mice morphologically. Hepatic TG content was decreased about 40 % (p < 0.05) in SKO mice fed with the DHA/EPA diet compared to chow fed SKO controls. Glucose and insulin tolerance were also improved significantly in SKO mice with DHA/EPA diet. In analyzing hepatic gene expression pattern it was found that TG synthesis related genes, such as carbohydrate response element binding protein (ChREBP), stearoyl-CoA desaturase 1 (SCD1) and fatty acid synthase (Fas) were upregulated in SKO mice compared to WT mice but were significantly decreased in SKO mice on DHA/EPA diet. Fatty acid β-oxidation related genes, on the other hand, such as peroxisome proliferator-activated receptor α (PPARα), carnitine palmitoyltransferase (CPT) and acyl-CoA oxidase 1 (ACOX1) were elevated in both WT and SKO groups on DHA/EPA diets. The protein levels of PPARα, SCD1, CPT1α, Insulin receptor substrate 1 (IRS1) and ratio of p-AKT to AKT showed the same tendency as the result of genes expressions.

CONCLUSIONS

The results suggest that n-3 PUFAs rich diet ameliorates lipodystrophy-induced hepatic steatosis through reducing TG synthesis, improving insulin resistance and enhancing β-oxidation in SKO mice.

Biallelic mutations at PPARG cause a congenital, generalized lipodystrophy similar to the Berardinelli-Seip syndrome

We present an individual with a generalized and infantile onset lipodystrophy who later developed hypertriglyceridemia, pancreatitis, refractory diabetes, irregular menses and renal failure. She showed the hallmark features of a congenital, generalized lipodystrophy (CGL). Sequencing PPARG identified two pathogenic mutations; c.413_416delAATG; p.Glu138ValfsX168 and c.490C>T; p.R164W. The phenotype and presence of two mutations suggests that biallelic mutations at PPARG cause a CGL similar to that observed with biallelic AGPAT2 or BSCL2 mutations.

Monogenic diabetes secondary to congenital lipodystrophy in a 14-year-old Yemeni girl

A 14-year-old female from Yemen presented with intense abdominal pain and headache. She was born at term to distant cousins, developmentally delayed and significantly dysmorphic. Four years ago, she was diagnosed with diabetes mellitus and undiagnosed hepatic, cardiac, genetic, neurologic, endocrine, musculoskeletal, and gastrointestinal disorders. No therapy was prescribed. Admission laboratory data showed blood glucose = 391 mg/dl, hemoglobin A1c= 12.2%, C-peptide = 3.5 ng/ml, insulin = 6.8 uIU/ml, triglyceride =385 mg/dl, and serum leptin <0.5 ng/ml, (1.1-27.5). Chromosome analysis (46, XX) was normal and serology for Glutamic acid Decarboxylase (GAD), hepatitis and HIV were negative. Clinical examination and laboratory data suggested congenital generalized lipodystrophy (CGL, type BSCL-2). This case illustrates that CGL should be in the differential diagnosis for non-obese patients with diabetes and insulin resistance.