Clinical presentations, metabolic abnormalities and end-organ complications in patients with familial partial lipodystrophy

Identification of novel genetic variations in ABCB6 and GRN genes associated with HIV-associated lipodystrophy

Protease inhibitors (PIs) are associated with an incidence of lipodystrophy among people living with HIV(PLHIV). Lipodystrophiesare characterised by the loss of adipose tissue. Evidence suggests that a patient's lipodystrophy phenotype is influenced by genetic mutation, age, gender, and environmental and genetic factors, such as single-nucleotide variants (SNVs). Pathogenic variants are considered to cause a more significant loss of adipose tissue compared to non-pathogenic. Lipid metabolising enzymes and transporter genes have a role in regulating lipoprotein metabolism and have been associated with lipodystrophy in HIV-infected patients (LDHIV). The long-term effect of the lipodystrophy syndrome is related to cardiovascular diseases (CVDs). Hence, we determined the SNVs of lipid metabolising enzymes and transporter genes in a total of 48 patient samples, of which 24 were with and 24 were without HIV-associated lipodystrophy (HIVLD) using next-generation sequencing. A panel of lipid metabolism, transport and elimination genes were sequenced. Three novel heterozygous non-synonymous variants at exon 8 (c.C1400A:p.S467Y, c.G1385A:p.G462E, and c.T1339C:p.S447P) in the ABCB6 gene were identified in patients with lipodystrophy. One homozygous non-synonymous SNV (exon5:c.T358C:p.S120P) in the GRN gene was identified in patients with lipodystrophy. One novelstop-gain SNV (exon5:c.C373T:p.Q125X) was found in the GRN gene among patients without lipodystrophy. Patients without lipodystrophy had one homozygous non-synonymous SNV (exon9:c.G1462T:p.G488C) in the ABCB6 gene. Our findings suggest that novel heterozygous non-synonymous variants in the ABCB6 gene may contribute to defective protein production, potentially intensifying the severity of lipodystrophy. Additionally, identifying a stop-gain SNV in the GRN gene among patients without lipodystrophy implies a potential role in the development of HIVLD.

Deciphering the Clinical Presentations in LMNA-related Lipodystrophy: Report of 115 Cases and a Systematic Review

CONTEXT

Lipodystrophy syndromes are a heterogeneous group of rare genetic or acquired disorders characterized by generalized or partial loss of adipose tissue. LMNA-related lipodystrophy syndromes are classified based on the severity and distribution of adipose tissue loss.

OBJECTIVE

We aimed to annotate all clinical and metabolic features of patients with lipodystrophy syndromes carrying pathogenic LMNA variants and assess potential genotype-phenotype relationships.

METHODS

We retrospectively reviewed and analyzed all our cases (n = 115) and all published cases (n = 379) curated from 94 studies in the literature.

RESULTS

The study included 494 patients. The most common variants in our study, R482Q and R482W, were associated with similar metabolic characteristics and complications though those with the R482W variant were younger (aged 33 [24] years vs 44 [25] years; P < .001), had an earlier diabetes diagnosis (aged 27 [18] vs 40 [17] years; P < .001) and had lower body mass index levels (24 [5] vs 25 [4]; P = .037). Dyslipidemia was the earliest biochemical evidence described in 83% of all patients at a median age of 26 (10) years, while diabetes was reported in 61% of cases. Among 39 patients with an episode of acute pancreatitis, the median age at acute pancreatitis diagnosis was 20 (17) years. Patients who were reported to have diabetes had 3.2 times, while those with hypertriglyceridemia had 12.0 times, the odds of having pancreatitis compared to those who did not.

CONCLUSION

This study reports the largest number of patients with LMNA-related lipodystrophy syndromes to date. Our report helps to quantify the prevalence of the known and rare complications associated with different phenotypes and serves as a comprehensive catalog of all known cases.

Clinical and imaging features of women with polygenic partial lipodystrophy: a case series

BACKGROUND

Familial partial lipodystrophy (FPLD) is an inherited disorder of white adipose tissue that causes premature cardiometabolic disease. There is no clear diagnostic criteria for FPLD, and this may explain the under-detection of this condition.

AIM

This pilot study aimed to describe the clinical features of women with FPLD and to explore the value of adipose tissue measurements that could be useful in diagnosis.

METHODS

In 8 women with FPLD and 4 controls, skinfold measurements, DXA and whole-body MRI were undertaken.

RESULTS

Whole genome sequencing was negative for monogenic metabolic causes, but polygenic scores for partial lipodystrophy were elevated in keeping with FPLD type 1. The mean age of diagnosis of DM was 31 years in the FPLD group. Compared with controls, the FPLD group had increased HOMA-IR (10.3 vs 2.9, p = 0.028) and lower mean thigh skinfold thickness (19.5 mm vs 48.2 mm, p = 0.008). The FPLD group had lower percentage of leg fat and an increased ratio of trunk to leg fat percentage on DXA. By MRI, the FPLD group had decreased subcutaneous adipose tissue (SAT) volume in the femoral and calf regions (p < 0.01); abdominal SAT, visceral adipose tissue, and femoral and calf muscle volumes were not different from controls.

CONCLUSION

Women with FPLD1 in Singapore have significant loss of adipose but not muscle tissue in lower limbs and have early onset of diabetes. Reduced thigh skinfold, and increased ratio of trunk to leg fat percentage on DXA are potentially clinically useful markers to identify FPLD1.

Natural history and comorbidities of generalised and partial lipodystrophy syndromes in Spain

The rarity of lipodystrophies implies that they are not well-known, leading to delays in diagnosis/misdiagnosis. The aim of this study was to assess the natural course and comorbidities of generalised and partial lipodystrophy in Spain to contribute to their understanding. Thus, a total of 140 patients were evaluated (77.1% with partial lipodystrophy and 22.9% with generalised lipodystrophy). Clinical data were collected in a longitudinal setting with a median follow-up of 4.7 (0.5-17.6) years. Anthropometry and body composition studies were carried out and analytical parameters were also recorded. The estimated prevalence of all lipodystrophies in Spain, excluding Köbberling syndrome, was 2.78 cases/million. The onset of phenotype occurred during childhood in generalised lipodystrophy and during adolescence-adulthood in partial lipodystrophy, with the delay in diagnosis being considerable for both cohorts. There are specific clinical findings that should be highlighted as useful features to take into account when making the differential diagnosis of these disorders. Patients with generalised lipodystrophy were found to develop their first metabolic abnormalities sooner and a different lipid profile has also been observed. Mean time to death was 83.8 ± 2.5 years, being shorter among patients with generalised lipodystrophy. These results provide an initial point of comparison for ongoing prospective studies such as the ECLip Registry study.

Waist circumference is independently associated with liver steatosis and fibrosis in LMNA-related and unrelated Familial Partial Lipodystrophy women

BACKGROUND

Lipodystrophies are a heterogeneous group of diseases characterized by the selective loss of subcutaneous adipose tissue and ectopic fat deposition in different organs, including the liver. This study aimed to determine the frequencies of liver steatosis (LS) and liver fibrosis (LF) in a sample of individuals with LMNA-related and unrelated Familial Partial Lipodystrophy.

METHODS

This cross-sectional study included 17 women with LMNA-related FPLD and 15 women with unrelated FPLD. LS and LF were assessed using transient elastography (TE) with FibroScan®. Anthropometric and biochemical variables were included in a multiple linear regression analysis to identify the variables that were independently related to liver disease.

RESULTS

Regarding the presence of LF, 22 (68.2%) women were classified as having non-significant fibrosis, and 10 (31.8%) were classified as having significant or severe fibrosis. Regarding LS, only six women (20.7%) were classified as having an absence of steatosis, and 23 (79.3%) had mild to severe steatosis. After multiple linear regression, waist circumference (but not age, body mass index, or waist-to-hip ratio) was found to be independently related to LS and LF. Among the biochemical variables, only triglyceride levels were independently related to LS but not LF.

CONCLUSIONS

In women with FPLD, visceral fat accumulation appears to be the most important determinant of liver disease, including LF, rather than fat scarcity in the lower limbs.

Familial Partial Lipodystrophy: Clinical Features, Genetics and Treatment in a Greek Referral Center

Familial partial lipodystrophy (FPLD) is a rare syndrome in which a patient's phenotype is not merely dependent on the specific genetic mutation, but it is also defined by a combination of other demographic, environmental and genetic factors. In this prospective observational study in a Greek referral center, we enrolled 39 patients who fulfilled the clinical criteria of FPLD. A genetic analysis was conducted, which included sequence and deletion/duplication analyses of the LMNA and PPRARG genes, along with anthropometric and metabolic parameters. The treatment responses of patients who were eligible for treatment with metreleptin were evaluated at 3 and 12 months. In most of the patients, no significant changes were detected at the exon level, and any mutations that led to changes at the protein level were not associated with the lipodystrophic phenotype. On the contrary, various changes were detected at the intron level, especially in introns 7 and 10, whose clinical significance is considered unknown. In addition, treatment with metreleptin in specific FPLD patients significantly improved glycemic and lipidemic control, an effect which was sustained at the 12-month follow-up. More large-scale studies are necessary to clarify the genetic and allelic heterogeneity of the disease, along with other parameters which could predict treatment response.

Clinical Spectrum of LMNA-Associated Type 2 Familial Partial Lipodystrophy: A Systematic Review

Type 2 familial partial lipodystrophy (FPLD2) is a laminopathic lipodystrophy due to pathogenic variants in the LMNA gene. Its rarity implies that it is not well-known. The aim of this review was to explore the published data regarding the clinical characterisation of this syndrome in order to better describe FPLD2. For this purpose, a systematic review through a search on PubMed until December 2022 was conducted and the references of the retrieved articles were also screened. A total of 113 articles were included. FPLD2 is characterised by the loss of fat starting around puberty in women, affecting limbs and trunk, and its accumulation in the face, neck and abdominal viscera. This adipose tissue dysfunction conditions the development of metabolic complications associated with insulin resistance, such as diabetes, dyslipidaemia, fatty liver disease, cardiovascular disease, and reproductive disorders. However, a great degree of phenotypical variability has been described. Therapeutic approaches are directed towards the associated comorbidities, and recent treatment modalities have been explored. A comprehensive comparison between FPLD2 and other FPLD subtypes can also be found in the present review. This review aimed to contribute towards augmenting knowledge of the natural history of FPLD2 by bringing together the main clinical research in this field.

Pelvis magnetic resonance imaging to diagnose familial partial lipodystrophy

CONTEXT

The diagnosis of familial partial lipodystrophy (FPLD) is currently made based on clinical judgement.

OBJECTIVE

There is a need for objective diagnostic tools that can diagnose FPLD accurately.

METHODS

We have developed a new method that used measurements from pelvic magnetic resonance imaging (MRI) at the pubis level. We evaluated measurements from a lipodystrophy cohort (n = 59; median age [25-75 percentiles]: 32 [24-44]; 48 females and 11 males) and age- and gender-matched controls (n = 29). Another dataset included MRIs from 289 consecutive patients.

RESULTS

Receiver operating characteristic curve (ROC) analysis revealed a potential cut-point of ≤ 13 mm gluteal fat thickness for the diagnosis of FPLD. A combination of gluteal fat thickness ≤ 13 mm and pubic/gluteal fat ratio ≥ 2.5 (based on a ROC) provided 96.67% (95% Confidence Interval [CI]: 82.78-99.92%) sensitivity and 91.38% (95% CI: 81.02-97.14%) specificity in the overall cohort and 100.00% (95% CI: 87.23-100.00%) sensitivity and 90.00% (95% CI: 76.34-97.21%) specificity in females for the diagnosis of FPLD. When this approach was tested in a larger dataset of random patients, FPLD was differentiated from subjects without lipodystrophy with 96.67% (95% CI: 82.78-99.92%) sensitivity and 100.00% (95% CI: 98.73-100.00%) specificity. When only women were analyzed, the sensitivity and the specificity was 100.00% (95%CI: 87.23-100.00% and 97.95-100.00%, respectively). The performance of gluteal fat thickness and pubic/gluteal fat thickness ratio was comparable to readouts performed by radiologists with expertise in lipodystrophy.

CONCLUSION

The combined use of gluteal fat thickness and pubic/gluteal fat ratio from pelvic MRI is a promising method to diagnose FPLD that can reliably identify FPLD in women. Our findings need to be tested in larger populations and prospectively.

Lipodystrophies in non-insulin-dependent children: Treatment options and results from recombinant human leptin therapy

Lipodystrophy is a general definition containing different pathologies which, except for those observed in insulin-treated subjects falling outside the scope of this paper, are characterized by total or partial lack of body fat, that, according to the amount of missing adipose tissue, are divided in generalized or partial lipodystrophy. These diseases are characterized by leptin deficiency, which often leads to metabolic derangement, causing insulin resistance, dyslipidemia, and increasing cardiovascular risk. In this narrative review, we presentend the clinical presentation of different types of lipodystrophies and metabolic unbalances related to disease in children and adolescents, focusing on the main treatment options and the novel results from recombinant human leptin (metreleptin) therapy. Milestones in the management of lipodystrophy include lifestyle modification as diet and physical activity, paired with hypoglycemic drugs, insulin, hypolipidemic drugs, and other drugs with the aim of treating lipodystrophy complications. Metreleptin has been recently approved for pediatric patients with general lipodystrophy (GL)> 2 years of age and for children with partial lipodystrophy (PL)> 12 years of age not controlled with conventional therapies. New therapeutic strategies are currently being investigated, especially for patients with PL forms, specifically, liver-targeted therapies. Further studies are needed to achieve the most specific and precise treatment possible.

Nucleoplasmic lamin C rapidly accumulates at sites of nuclear envelope rupture with BAF and cGAS

In mammalian cell nuclei, the nuclear lamina (NL) underlies the nuclear envelope (NE) to maintain nuclear structure. The nuclear lamins, the major structural components of the NL, are involved in the protection against NE rupture induced by mechanical stress. However, the specific role of the lamins in repair of NE ruptures has not been fully determined. Our analyses using immunofluorescence and live-cell imaging revealed that the nucleoplasmic pool of lamin C rapidly accumulated at sites of NE rupture induced by laser microirradiation in mouse embryonic fibroblasts. The accumulation of lamin C at the rupture sites required both the immunoglobulin-like fold domain that binds to barrier-to-autointegration factor (BAF) and a nuclear localization signal. The accumulation of nuclear BAF and cytoplasmic cyclic GMP-AMP synthase (cGAS) at the rupture sites was in part dependent on lamin A/C. These results suggest that nucleoplasmic lamin C, BAF, and cGAS concertedly accumulate at sites of NE rupture for rapid repair.

Describing the natural history of clinical, biochemical and radiological outcomes of children with familial partial lipodystrophy type 2 (FPLD2) from the United Kingdom: A retrospective case series

CONTEXT

Familial partial lipodystrophy type 2 (FPLD2) results from autosomal dominant mutations in the LMNA gene, causing lack of subcutaneous fat deposition and excess ectopic fat accumulation, leading to metabolic complications and reduced life expectancy. The rarity of the condition means that the natural history of FPLD2 throughout childhood is not well understood. We report outcomes in a cohort of 12 (5M) children with a genetic diagnosis of FPLD2, under the care of the UK National Severe Insulin Resistance Service (NSIRS) which offers multidisciplinary input including dietetic, in addition to screening for comorbidities.

OBJECTIVE

To describe the natural history of clinical, biochemical and radiological outcomes of children with FPLD2.

DESIGN

A retrospective case note review of children with a genetic diagnosis of FPLD2 who had been seen in the paediatric NSIRS was performed.

PATIENTS

Twelve (5M) individuals diagnosed with FPLD2 via genetic testing before age 18 and who attended the NSIRS clinic were included.

MEASUREMENTS

Relationships between metabolic variables (HbA1c, triglycerides, fasting insulin, fasting glucose and alanine transaminase [ALT]) across time, from first visit to most recent, were explored using a multivariate model, adjusted for age and gender. The age of development of comorbidities was recorded.

RESULTS

Three patients (all female) developed diabetes between 12 and 19 years and were treated with Metformin. One female has hypertrophic cardiomyopathy and four (1M) patients developed mild hepatic steatosis at a median [range] age of 14(12-15) years. Three (1M) patients reported mental health problems related to lipodystrophy. There was no relationship between biochemical results and age. Patients with diabetes had higher concentrations of ALT than patients who did not have diabetes, adjusted for age, gender and body mass index standard deviation scores.

CONCLUSIONS

Despite dietetic input, some patients, more commonly females, developed comorbidities after the age of 10. The absence of relationships between biochemical results and age likely reflects a small cohort size. We propose that, while clinical review and dietetic support are beneficial for children with FPLD2, formal screening for comorbidities before age 10 may not be of benefit. Clinical input from an multidisciplinary team including dietician, psychologist and clinician should be offered after diagnosis.

Severe loss of adipose tissue in a Vietnamese lipodystrophy patient caused by LMNA p.G465D mutation: a first clinical characterization and two-year follow-up

OBJECTIVES

Familial partial lipodystrophy type 2 is the most well-known subtype of lipodystrophy. We describe for the first time the phenotype of a case with lipodystrophy, who carried heterozygous mutation c.G1394A (p.G465D) in the LMNA gene.

CASE PRESENTATION

A 17-year-old girl was diagnosed with FPLD2 due to severe loss of subcutaneous fat in the extremities, buttocks and metabolic complications. However, there was no accumulation of fat over her face and neck, which is remarkably different from the FPLD2 clinical phenotypes. Two years of surveillance showed the challenge due to unable control of insulin resistance, glucose and lipid metabolism. Whole exome sequencing revealed the heterozygous mutation c.1394G>A at exon 11 of LMNA gene (p.G465D).

CONCLUSIONS

Our case displayed an atypical phenotype of FPLD2 with metabolic anomalies, not cardiovascular diseases. The difficulties of medical management in this case pointed out the urgent need for more effective treatment for individuals suffering from this rare disease.

Endogenous Leptin Concentrations Poorly Predict Metreleptin Response in Patients With Partial Lipodystrophy

CONTEXT

Leptin replacement with metreleptin improves glycemia and hypertriglyceridemia in severely hypoleptinemic patients with generalized lipodystrophy (GLD), but its effects are variable in partially leptin-deficient patients with partial lipodystrophy (PLD).

OBJECTIVE

Compare 3 leptin assays (Study I); identify diagnostic performance of leptin assays to detect responders to metreleptin for each assay (Study II).

DESIGN

Study I: cross-sectional analysis of average bias between leptin assays. Study II: retrospective analysis of diagnostic accuracy of potential leptin cut points to detect clinical responders to metreleptin.

SETTING

National Institutes of Health; University of Michigan.

PARTICIPANTS AND INTERVENTIONS

Study I: Metreleptin-naïve patients with lipodystrophy (GLD, n = 33, PLD, n = 67) and healthy volunteers (n = 239). Study II: GLD (n = 66) and PLD (n = 84) patients treated with metreleptin for 12 months.

OUTCOME MEASURES

Leptin concentrations by Millipore radioimmunoassay (RIA), Millipore enzyme-linked immunosorbent assay (MELISA), and R&D Systems enzyme-linked immunosorbent assay (RDELISA). Response to metreleptin therapy was defined as either reduction ≥1.0% in A1c or ≥30% in serum triglycerides.

RESULTS

RDELISA measured 3.0 ± 9.5 ng/mL higher than RIA; MELISA measured 11.0 ± 17.8 and 14.0 ±19.2 less than RIA and RDELISA, respectively. Leptin by RIA, MELISA, and RDELISA modestly predicted metreleptin response in GLD + PLD [receiver operating characteristic (ROC) area under the curve (AUC) 0.74, 0.69, and 0.71, respectively; P < 0.01 for all] with lower predictive power in PLD (ROC AUC 0.63, 0.61 and 0.65, respectively; P > 0.05 for all). The only reproducible cut point identified on sensitivity analyses was RIA leptin 7.2 ng/mL (sensitivity 56%; specificity 78%).

CONCLUSIONS

Three common leptin assays are not interchangeable, and a reliable cut point to select responders to metreleptin was not identified.

NAFLD in normal weight individuals

Nonalcoholic fatty liver disease (NAFLD) can develop in lean individuals. Despite a better metabolic profile, the risk of disease progression to hepatic inflammation, fibrosis, and decompensated cirrhosis in the lean is similar to that in obesity-related NAFLD and lean individuals may experience more severe hepatic consequences and higher mortality relative to those with a higher body mass index (BMI). In the absence of early symptoms and abnormal laboratory findings, lean individuals are not likely to be screened for NAFLD or related comorbidities; however, given the progressive nature of the disease and the increased risk of morbidity and mortality, a clearer understanding of the natural history of NAFLD in lean individuals, as well as efforts to raise awareness of the potential health risks of NAFLD in lean individuals, are warranted. In this review, we summarize available data on NAFLD prevalence, clinical characteristics, outcomes, and mortality in lean individuals and discuss factors that may contribute to the development of NAFLD in this population, including links between dietary and genetic factors, menopausal status, and ethnicity. We also highlight the need for greater representation of lean individuals in NAFLD-related clinical trials, as well as more studies to better characterize lean NAFLD, develop improved screening algorithms, and determine specific treatment strategies based on underlying etiology.

Circulating Levels of MiRNAs From 320 Family in Subjects With Lipodystrophy: Disclosing Novel Signatures of the Disease

Lipodystrophy (LD) indicates a group of rare disorders, with generalized or partial loss of white adipose tissue (WAT) often associated with metabolic derangements. Heterogeneity/wide spectrum of the disease and lack of biomarkers make diagnosis often difficult. MicroRNAs are important to maintain a correct WAT function and WAT is a source of circulating miRNAs (cmiRs). miRNAs from 320 family were previously detected in the WAT and variably associated to the metabolic syndrome. Our aim was then to investigate if LD can result in altered abundance of cmiRs-320. We collected samples from a cohort of LD subjects of various subtypes and from age matched controls. Use of quantitative PCR determined that cmiRs- 320a-3p, 320b, 320c, 320e are upregulated, while 320d is downregulated in LD. CmiRs-320 power as classifiers was more powerful in the most extreme and defined forms of LD, including the generalized and the Dunnigan subtypes. cmiR-320a-3p showed significant inverse relationships with plasma leptin (P < 0.0001), typically low in LD. The hepatic enzymes gamma-glutamyl transferase (GGT), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and the marker of inflammation C-reactive protein (CRP) were inversely related to cmiR 320d (P < 0.05, for CRP and GGT; P < 0.01, for AST and ALT). Gene ontology analysis revealed cell-cell adhesion as a process regulated by 320 miRNAs targets, thus disclosing a novel route to investigate origin of WAT loss/dysfunction. In conclusion, cmiRs-320 constitute novel biomarkers of LD, abundance of miR320a-3p is inversely associated to indicators related to WAT function, while downregulation of cmiR-320d predicts an altered hepatic profile and higher inflammation.

A Rare Mutation in LMNB2 Associated with Lipodystrophy Drives Premature Cell Senescence

Many proteins are causative for inherited partial lipodystrophies, including lamins, the essential constituents of the nuclear envelope scaffold called the lamina. By performing high throughput sequencing on a panel of genes involved in lipodystrophies, we identified a heterozygous mutation in LMNB2 gene (c.700C > T p.(Arg234Trp)) in a female patient presenting early onset type II diabetes, hypertriglyceridemia, and android fat distribution. This mutation is rare in the general population (frequency 0.013% in GnomAD) and was predicted pathogenic by a set of pathogenicity prediction software. Patient-derived fibroblasts showed nuclear shape abnormalities and premature senescence features, which are two typical cellular phenotypes associated with laminopathies. Moreover, we observed an atypical aggregation of lamin B2 in nucleoplasm, which co-distributes with emerin and lamin A/C, along with an abnormal distribution of lamin A/C at the nuclear envelope. Finally, reducing lamin B2 expression level by siRNA targeted toward LMNB2 transcripts resulted in decreased nuclear anomalies and senescence-associated beta-galactosidase, suggesting a role of the mutated protein in the occurrence of the observed cellular phenotype. Altogether, these results suggest that mutations in lamin B2 could produce premature senescence and partial lipodystrophy features as observed with certain mutants of lamin A/C.

Selective targeting of angiopoietin-like 3 (ANGPTL3) with vupanorsen for the treatment of patients with familial partial lipodystrophy (FPLD): results of a proof-of-concept study

BACKGROUND

Familial partial lipodystrophy (FPLD) is a rare disease characterized by selective loss of peripheral subcutaneous fat, associated with dyslipidemia and diabetes mellitus. Reductions in circulating levels of ANGPTL3 are associated with lower triglyceride and other atherogenic lipids, making it an attractive target for treatment of FPLD patients. This proof-of-concept study was conducted to assess the efficacy and safety of targeting ANGPTL3 with vupanorsen in patients with FPLD.

METHODS

This was an open-label study. Four patients with FPLD (two with pathogenic variants in LMNA gene, and two with no causative genetic variant), diabetes (HbA1c ≥ 7.0 % and ≤ 12 %), hypertriglyceridemia (≥ 500 mg/dL), and hepatic steatosis (hepatic fat fraction, HFF ≥ 6.4 %) were included. Patients received vupanorsen subcutaneously at a dose of 20 mg weekly for 26 weeks. The primary endpoint was the percent change from baseline in fasting triglycerides at Week 27. Other endpoints analyzed at the same time point included changes in ANGPTL3, fasting lipids and lipoproteins, insulin secretion/sensitivity, postprandial lipids, and glycemic changes in response to a mixed meal test, HFF measured by MRI, and body composition measured by dual-energy absorptiometry (DEXA).

RESULTS

Baseline mean ± SD fasting triglyceride level was 9.24 ± 4.9 mmol/L (817.8 ± 431.9 mg/dL). Treatment resulted in reduction in fasting levels of triglycerides by 59.9 %, ANGPTL3 by 54.7 %, and in several other lipoproteins/lipids, including very low-density lipoprotein cholesterol by 53.5 %, non-high-density lipoprotein cholesterol by 20.9 %, and free fatty acids (FFA) by 41.7 %. The area under the curve for postprandial triglycerides, FFA, and glucose was reduced by 60 %, 32 %, and 14 %, respectively. Treatment with vupanorsen also resulted in 55 % reduction in adipose tissue insulin resistance index, while other insulin sensitivity indices and HbA1c levels were not changed. Additional investigations into HFF and DEXA parameters suggested dynamic changes in fat partitioning during treatment. Adverse events observed were related to common serious complications associated with diabetes and FPLD. Vupanorsen was well tolerated, and there was no effect on platelet count.

CONCLUSIONS

Although limited, these results suggest that targeting ANGPTL3 with vupanorsen could address several metabolic abnormalities in patients with FPLD.

Genotype - phenotype correlation in an adolescent girl with pathogenic variant in PPARƴ gene causing severe hypertriglyceridemia and early onset type 2 diabetes

Severe hypertriglyceridemia (HTG) (>885 mg/dl) can be caused by familial partial lipodystrophy Type 3 (FPLD 3), an autosomal dominant disorder caused by a loss of function of the peroxisome proliferator activated receptor gamma (PPARG), characterized by abnormal distribution of fat and metabolic derangements. A 16-year-old female (body mass index, BMI 23.5 kg/m2) was hospitalized twice for pancreatitis (TG level >2200 mg/dl). She was managed with bowel rest, insulin infusion, and plasmapheresis. On a low fat 10 g daily diet and fenofibrate 160 mg daily her fasting TG had decreased to 411 mg/dL (range 0-149). She had a normal leptin level. Panel testing of genes involved in triglyceride metabolism revealed a known pathogenic variant in PPARG gene (c.452A>G p.Tyr151Cys). A second variant detected in this gene, c.1003G>C (p.Val335Leu), is considered benign. HbA1C of 6.6% and two-hours oral glucose tolerance test confirmed Type 2 diabetes (T2DM). We outline the earliest description of T2DM in an adolescent with a pathogenic variant of PPARG. PPARG related FLPD 3 should be considered in lean children presenting with severe HTG and insulin resistance and treatment with PPARy agonists Thiazolidinediones should be considered.

Complications of lipodystrophy syndromes

Lipodystrophy syndromes are rare complex multisystem disorders caused by generalized or partial lack of adipose tissue. Adipose tissue dysfunction in lipodystrophy is associated with leptin deficiency. Lipodystrophy leads to severe metabolic problems. These abnormalities include, but are not limited to, insulin-resistant diabetes, severe hypertriglyceridemia, and lipid accumulation in ectopic organs such as the liver, and are associated with end-organ complications. Metabolic abnormalities can be present at the time of diagnosis or may develop over time as the disease progresses. In addition to metabolic abnormalities, subtype-specific presentations due to underlying molecular etiology in genetic forms and autoimmunity in acquired forms contribute to severe morbidity in lipodystrophy.

Risk factors for diabetic foot ulcers in metreleptin naïve patients with lipodystrophy

AIM

Patients with lipodystrophy are at high risk for chronic complications of diabetes. Recently, we have reported 18 diabetic foot ulcer episodes in 9 subjects with lipodystrophy. This current study aims to determine risk factors associated with foot ulcer development in this rare disease population.

METHODS

Ninety metreleptin naïve patients with diabetes registered in our national lipodystrophy database were included in this observational retrospective cohort study (9 with and 81 without foot ulcers).

RESULTS

Patients with lipodystrophy developing foot ulcers had longer diabetes duration (p = 0.007), longer time since lipodystrophy diagnosis (p = 0.008), and higher HbA1c levels (p = 0.041). Insulin use was more prevalent (p = 0.003). The time from diagnosis of diabetes to first foot ulcer was shorter for patients with generalized lipodystrophy compared to partial lipodystrophy (p = 0.036). Retinopathy (p < 0.001), neuropathy (p < 0.001), peripheral artery disease (p = 0.001), and kidney failure (p = 0.003) were more commonly detected in patients with foot ulcers. Patients with foot ulcers tended to have lower leptin levels (p = 0.052). Multiple logistic regression estimated significant associations between foot ulcers and generalized lipodystrophy (OR: 40.81, 95% CI: 3.31-503.93, p = 0.004), long-term diabetes (≥ 15 years; OR: 27.07, 95% CI: 2.97-246.39, p = 0.003), and decreased eGFR (OR: 13.35, 95% CI: 1.96-90.67, p = 0.008).

CONCLUSIONS

Our study identified several clinical factors associated with foot ulceration among patients with lipodystrophy and diabetes. Preventive measures and effective treatment of metabolic consequences of lipodystrophy are essential to prevent the occurrence of foot ulcers in these high-risk individuals.

Novel clinical features and pleiotropic effect in three unrelated patients with LMNA variant

LMNA gene encodes A-type lamins and the encoded proteins join the structure of the nuclear lamina and affect the processes of nuclear homeostasis, DNA replication, repair, transcription, and apoptosis. LMNA variants cause a heterogeneous group of diseases known as laminopathies. Phenotypes associated with LMNA variants mainly affect the heart, skeleton, skin, bones, and nervous system. The affected tissues may vary depending on the site of the variant on the gene and the variation type. Complex phenotypes may also occur in some cases, in which findings of premature aging, cardiomyopathy, mandibuloacral dysplasia, lipodystrophy, renal involvement, metabolic involvement, and myopathy coexist. The pleiotropic effect of LMNA variants can result in heterogeneous phenotypes. In this study, we aimed to describe atypical phenotypic characteristics in a patient with familial partial lipodystrophy type 2 associated with LMNA variant, another with mandibuloacral dysplasia, and a third patient with a complex phenotype as well as discuss them in the context of their relationship with the genotype.

Cardiac phenotype in familial partial lipodystrophy

OBJECTIVES

LMNA variants have been previously associated with cardiac abnormalities independent of lipodystrophy. We aimed to assess cardiac impact of familial partial lipodystrophy (FPLD) to understand the role of laminopathy in cardiac manifestations.

STUDY DESIGN

Retrospective cohort study.

METHODS

Clinical data from 122 patients (age range: 13-77, 101 females) with FPLD were analysed. Mature human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) from a patient with an LMNA variant were studied as proof-of-concept for future studies.

RESULTS

Subjects with LMNA variants had a higher prevalence of overall cardiac events than others. The likelihood of having an arrhythmia was significantly higher in patients with LMNA variants (OR: 3.77, 95% CI: 1.45-9.83). These patients were at higher risk for atrial fibrillation or flutter (OR: 5.78, 95% CI: 1.04-32.16). The time to the first arrhythmia was significantly shorter in the LMNA group, with a higher HR of 3.52 (95% CI: 1.34-9.27). Non-codon 482 LMNA variants were more likely to be associated with cardiac events (vs. 482 LMNA: OR: 4.74, 95% CI: 1.41-15.98 for arrhythmia; OR: 17.67, 95% CI: 2.45-127.68 for atrial fibrillation or flutter; OR: 5.71, 95% CI: 1.37-23.76 for conduction disease). LMNA mutant hiPSC-CMs showed a higher frequency of spontaneous activity and shorter action potential duration. Functional syncytia of hiPSC-CMs displayed several rhythm alterations such as early afterdepolarizations, spontaneous quiescence and spontaneous tachyarrhythmia, and significantly slower recovery in chronotropic changes induced by isoproterenol exposure.

CONCLUSIONS

Our results highlight the need for vigilant cardiac monitoring in FPLD, especially in patients with LMNA variants who have an increased risk of developing cardiac arrhythmias. In addition, hiPSC-CMs can be studied to understand the basic mechanisms for the arrhythmias in patients with lipodystrophy to understand the impact of specific mutations.

Novel PPARG mutation in multiple family members with chylomicronemia

Chylomicronemia is characterized by severe hypertriglyceridemia when chylomicrons persist in plasma despite a fasting state. The recessive monogenic form is due to homozygous or compound heterozygous loss-of-function mutations in the LPL gene or genes involved in the assembly, transport, or function of LPL, including APOC2, APOA5, GP1HBP1, and LMF1. The multifactorial form of chylomicronemia is due to both common small-effect variants and rare heterozygous large-effect variants in genes in which mutations are associated secondarily with hypertriglyceridemia. The combined inheritance of these variants increases susceptibility to chylomicronemia, and the number of hypertriglyceridemia-associated alleles carried by an individual represents a genetic or polygenic triglyceride risk score. Among these genes associated with hypertriglyceridemia is PPARG. PPARγ is a nuclear transcription factor encoded by the PPARG gene expressed predominantly in adipocytes that is involved in glucose, lipid, and adipose tissue metabolism. Known rare mutations and common polymorphisms in the PPARG genes are associated with a broad range of clinical phenotypes, including hypertriglyceridemia. Here, we present multiple family members with a novel heterozygous PPARG mutation that has not been previously reported.

Variable Expressivity in Type 2 Familial Partial Lipodystrophy Related to R482 and N466 Variants in the LMNA Gene

Patients with Dunnigan disease (FPLD2) with a pathogenic variant affecting exon 8 of the LMNA gene are considered to have the classic disease, whereas those with variants in other exons manifest the "atypical" disease. The aim of this study was to investigate the degree of variable expressivity when comparing patients carrying the R482 and N466 variants in exon 8. Thus, 47 subjects with FPLD2 were studied: one group of 15 patients carrying the N466 variant and the other group of 32 patients with the R482 variant. Clinical, metabolic, and body composition data were compared between both groups. The thigh skinfold thickness was significantly decreased in the R482 group in comparison with the N466 group (4.2 ± 1.8 and 5.6 ± 2.0 mm, respectively, p = 0.002), with no other differences in body composition. Patients with the N466 variant showed higher triglyceride levels (177.5 [56-1937] vs. 130.0 [55-505] mg/dL, p = 0.029) and acute pancreatitis was only present in these subjects (20%). Other classic metabolic abnormalities related with the disease were present regardless of the pathogenic variant. Thus, although FPLD2 patients with the R482 and N466 variants share most of the classic characteristics, some phenotypic and metabolic differences suggest possible heterogeneity even within exon 8 of the LMNA gene.

The Metabolic Equivalent BMI in Patients with Familial Partial Lipodystrophy (FPLD) Compared with Those with Severe Obesity

OBJECTIVE

This study aimed to investigate the shortcoming of BMI as a measurement of adiposity in patients with familial partial lipodystrophy (FPLD).

METHODS

Two different matching procedures were used to compare 55 FPLD versus control patients with severe obesity (N = 548 patients) to study the relationship between body weight, fat distribution, and metabolic diseases, such as diabetes mellitus, hypertriglyceridemia, and nonalcoholic steatohepatitis. In MATCH1, the patients with FPLD were matched to controls with obesity (OCs) by truncal mass, and in MATCH2, the patients with FPLD were matched to OCs with respect to glucose control.

RESULTS

With MATCH1, the FPLD group had worse glycemic control (hemoglobin A1c 8.2% ± 1.6% vs. 5.9% ± 0.9%), higher triglycerides (884 ± 1,190 mg/dL vs. 139 ± 79 mg/dL), and lower leptin (20.5 ± 15.8 ng/mL vs. 41.9 ± 29.4 ng/mL, P < 0.001 for all comparisons). In MATCH2, metabolic comorbidity-matched FPLD patients had significantly lower BMI compared with OCs (29.5 ± 5.7 kg/m² vs. 38.6 ± 5.2 kg/m² , P < 0.001).

CONCLUSIONS

Patients with FPLD with similar truncal mass have worse metabolic profiles than non-FPLD OCs. The differential BMI between the FPLD and OCs, when matched for their metabolic comorbidities, approximates 8.6 BMI units.

Case Report: Metreleptin Treatment in a Patient With a Novel Mutation for Familial Partial Lipodystrophy Type 3, Presenting With Uncontrolled Diabetes and Insulin Resistance

BACKGROUND

Familial partial lipodystrophy type 3 (FPLD3) is a very rare autosomal dominant genetic disorder which is caused by mutations in the peroxisome proliferator activated receptor gamma (PPARG) gene. It is characterized by a partial loss of adipose tissue leading to subnormal leptin secretion and metabolic complications. Metreleptin, a synthetic analogue of human leptin, is an effective treatment for generalized lipodystrophies, but the evidence for efficacy in patients with FPLD3 is scarce.

CASE PRESENTATION

We present a 61-year-old woman, initially misdiagnosed as type 1 diabetes since the age of 29, with severe insulin resistance, who gradually displayed a more generalized form of lipoatrophy and extreme hypertriglyceridemia, hypertension and multiple manifestations of cardiovascular disease. She was found to carry a novel mutation leading to PPARG_Glu157Gly variant. After six months of metreleptin treatment, HbA1c decreased from 10 to 7.9% and fasting plasma triglycerides were dramatically reduced from 2.919 mg/dl to 198 mg/dl.

CONCLUSIONS

This case highlights the importance of early recognition of FPLD syndromes otherwise frequently observed as difficult-to-classify and manages diabetes cases, in order to prevent cardiovascular complications. Metreleptin may be an effective treatment for FPLD3.

Magnetic resonance spectroscopy to assess hepatic steatosis in patients with lipodystrophy

BACKGROUND/AIMS

Lipodystrophy is a rare metabolic disorder characterized by near total or partial lack of subcutaneous adipose tissue and associated with insulin resistance. We aimed to evaluate the efficacy of magnetic resonance spectroscopy imaging (MRS) to explore the fat content of the liver in patients with lipodystrophy and to determine the relationship between the liver fat accumulation and clinical presentations of lipodystrophy.

MATERIALS AND METHODS

Between July 2014 and February 2016, 34 patients with lipodystrophy were assessed by MRS for quantification of hepatic steatosis. All patients had metabolic abnormalities associated with insulin resistance. Metabolic parameters and the MRS findings were analyzed to identify potential correlations between the liver fat content and disease severity.

RESULTS

The MRS fat ratios (MRS-FR) were markedly higher, indicating severe hepatic steatosis in lipodystrophy. Patients with generalized and partial lipodystrophy had comparable levels of MRS-FRs, although patients with generalized lipodystrophy were significantly younger. Patients with genetically based lipodystrophy had elevated MRS-FR compared to those with acquired lipodystrophy (p=0.042). The MRS-FR was positively correlated with liver enzyme alanine aminotransferase (p=0.028) and serum adiponectin (p=0.043).

CONCLUSION

Our data suggest that MRS might be an effective, noninvasive imaging method to quantify hepatic fat content in patients with lipodystrophy. Further studies are needed to validate the technique and threshold values which would allow accurate comparison of data acquired by different machines and centers.

Atypical Progeroid Syndrome and Partial Lipodystrophy Due to LMNA Gene p.R349W Mutation

Atypical progeroid syndrome (APS) comprises heterogeneous disorders characterized by variable degrees of fat loss, metabolic alterations, and comorbidities that affect skeleton, muscles, and/or the heart. We describe 3 patients that were referred to our center for the suspicion of lipodystrophy. They had precocious aging traits such as short stature, mandibular hypoplasia, beaked nose, and partial alopecia manifesting around 10 to 15 years of age recurrently associated with: (1) partial lipodystrophy; (2) proteinuric nephropathy; (3) heart disease (rhythm disorders, valvular abnormalities, and cardiomyopathy); and (4) sensorineural hearing impairment. In all patients, genetic testing revealed a missense heterozygous lamin A/C gene (LMNA) mutation c.1045 C > T (p.Arg349Trp). Ten patients with LMNA p.R349W mutation have been reported so far, all presenting with similar features, which represent the key pathological hallmarks of this subtype of APS. The associated kidney and cardiac complications occurring in the natural history of the disease may reduce life expectancy. Therefore, in these patients a careful and periodic cardiac and kidney function evaluation is required.

Multisystem Progeroid Syndrome With Lipodystrophy, Cardiomyopathy, and Nephropathy Due to an LMNA p.R349W Variant

Background

Pathogenic variants in lamin A/C (LMNA) cause a variety of progeroid disorders including Hutchinson-Gilford progeria syndrome, mandibuloacral dysplasia, and atypical progeroid syndrome. Six families with 11 patients harboring a pathogenic heterozygous LMNA c.1045C>T; p.R349W variant have been previously reported to have partial lipodystrophy, cardiomyopathy, and focal segmental glomerulosclerosis (FSGS), suggesting a distinct progeroid syndrome.

Methods

We report 6 new patients with a heterozygous LMNA p.R349W variant and review the phenotype of previously reported patients to define their unique characteristics. We also performed functional studies on the skin fibroblasts of a patient to seek the underlying mechanisms of various clinical manifestations.

Results

Of the total 17 patients, all 14 adults with the heterozygous LMNA p.R349W variant had peculiar lipodystrophy affecting the face, extremities, palms, and soles with variable gain of subcutaneous truncal fat. All of them had proteinuric nephropathy with FSGS documented in 7 of them. Ten developed cardiomyopathy, and 2 of them died early at ages 33 and 45 years. Other common features included premature graying, alopecia, high-pitched voice, micrognathia, hearing loss, and scoliosis. Metabolic complications, including diabetes mellitus, hypertriglyceridemia, and hepatomegaly, were highly prevalent. This variant did not show any abnormal splicing, and no abnormal nuclear morphology was noted in the affected fibroblasts.

Conclusions

The heterozygous LMNA p.R349W variant in affected individuals has several distinct phenotypic features, and these patients should be classified as having multisystem progeroid syndrome (MSPS). MSPS patients should undergo careful assessment at symptom onset and yearly metabolic, renal, and cardiac evaluation because hyperglycemia, hypertriglyceridemia, FSGS, and cardiomyopathy cause major morbidity and mortality.

Homozygous LMNA p.R582H pathogenic variant reveals increasing effect on the severity of fat loss in lipodystrophy

Background

Classical heterozygous pathogenic variants of the lamin A/C (LMNA) gene cause autosomal dominant familial partial lipodystrophy type 2 (FPLD2). However, recent reports indicate phenotypic heterogeneity among carriers of LMNA pathogenic variants, and a few patients have been associated with generalized fat loss.

Case presentation

Here, we report a patient with a lamin A specific pathogenic variant in exon 11, denoted LMNA (c.1745G > A; p.R582H), present in the homozygous state. Fat distribution was compared radiographically to an unrelated heterozygote LMNA p.R582H patient from another pedigree, a healthy female control, a series of adult female subjects with congenital generalized lipodystrophy type 1 (CGL1, n = 9), and typical FPLD2 (n = 8). The whole-body MRI of the index case confirmed near-total loss of subcutaneous adipose tissue with well-preserved fat in the retroorbital area, palms and soles, mons pubis, and external genital region. This pattern resembled the fat loss pattern observed in CGL1 with only one difference: strikingly more fat was observed around mons pubis and the genital region. Also, the p.R582H LMNA variant in homozygous fashion was associated with lower leptin level and earlier onset of metabolic abnormalities compared to heterozygous p.R582H variant and typical FPLD2 cases. On the other hand, the heterozygous LMNA p.R582H variant was associated with partial fat loss which was similar to typical FPLD2 but less severe than the patients with the hot-spot variants at position 482.

Conclusions

Our observations and radiological comparisons demonstrate an additive effect of LMNA pathogenic variants on the severity of fat loss and add to the body of evidence that there may be complex genotype-phenotype relationships in this interesting disease known as FPLD2. Although the pathological basis for fat loss is not well understood in patients harboring pathogenic variants in the LMNA gene, our observation suggests that genetic factors modulate the extent of fat loss in LMNA associated lipodystrophy.

UNUSUAL PRESENTATIONS OF LMNA-ASSOCIATED LIPODYSTROPHY WITH COMPLEX PHENOTYPES AND GENERALIZED FAT LOSS: WHEN THE GENETIC DIAGNOSIS UNCOVERS NOVEL FEATURES

Objective

Lipodystrophy represents a group of rare diseases characterized by loss of body fat. While patients with generalized lipodystrophy exhibit near-total lack of fat, partial lipodystrophy is associated with selective fat loss affecting certain parts of the body. Although classical familial partial lipodystrophy (FPLD) is a well-described entity, recent reports indicate phenotypic heterogeneity among carriers of LMNA pathogenic variants.

Methods

We have encountered 2 unique cases with complex phenotypes, generalized fat loss, and very low leptin levels that made the distinction between generalized versus partial lipodystrophy quite challenging.

Results

We present a 61-year-old female with generalized fat loss, harboring the heterozygous pathogenic variant p.R541P (c.1622G>C) on the LMNA gene. The discovery of the pathogenic variant led to correct clinical diagnosis of her muscle disease, identification of significant heart disease, and a recommendation for the implantation of a defibrillator. She was able to start metreleptin based on her generalized fat loss pattern and demonstration of the genetic variant. Secondly, we report a 40-year-old Turkish female with generalized fat loss associated with a novel heterozygous LMNA pathogenic variant p.K486E (c.1456A>G), who developed systemic B cell follicular lymphoma.

Conclusion

Clinicians need to recognize that the presence of an LMNA variant does not universally lead to FPLD type 2, but may lead to a phenotype that is more complex and may resemble more closely generalized lipo-dystrophy. Additionally, providers should recognize the multisystem features of laminopathies and should screen for these features in affected patients, especially if the variant is not at the known hotspot for FPLD type 2.

Current Diagnosis, Treatment and Clinical Challenges in the Management of Lipodystrophy Syndromes in Children and Young People

Lipodystrophy is a heterogeneous group of disorders characterized by lack of body fat in characteristic patterns, which can be genetic or acquired. Lipodystrophy is associated with insulin resistance that can develop in childhood and adolescence, and usually leads to severe metabolic complications. Diabetes mellitus, hypertriglyceridemia, and hepatic steatosis ordinarily develop in these patients, and most girls suffer from menstrual abnormalities. Severe complications develop at a relatively young age, which include episodes of acute pancreatitis, renal failure, cirrhosis, and complex cardiovascular diseases, and all of these are associated with serious morbidity. Treatment of lipodystrophy consists of medical nutritional therapy, exercise, and the use of anti-hyperglycemic and lipid-lowering agents. New treatment modalities, such as metreleptin replacement, promise much in the treatment of metabolic abnormalities secondary to lipodystrophy. Current challenges in the management of lipodystrophy in children and adolescents include, but are not limited to: (1) establishing specialized centers with experience in providing care for lipodystrophy presenting in childhood and adolescence; (2) optimizing algorithms that can provide some guidance for the use of standard and novel therapies to ensure adequate metabolic control and to prevent complications; (3) educating patients and their parents about lipodystrophy management; (4) improving patient adherence to chronic therapies; (5) reducing barriers to access to novel treatments; and (5) improving the quality of life of these patients and their families.

Diagnostic strategies and clinical management of lipodystrophy

Introduction: Lipodystrophy is a heterogeneous group of rare diseases characterized by various degrees of fat loss which leads to serious morbidity due to metabolic abnormalities associated with insulin resistance and subtype-specific clinical features associated with underlying molecular etiology.Areas covered: This article aims to help physicians address challenges in diagnosing and managing lipodystrophy. We systematically reviewed the literature on PubMed and Google Scholar databases to summarize the current knowledge in lipodystrophy management.Expert opinion: Adipose tissue is a highly active endocrine organ that regulates metabolic homeostasis in the human body through a comprehensive communication network with other organ systems such as the central nervous system, liver, digestive system, and the immune system. The adipose tissue is capable of producing and secreting numerous factors with important endocrine functions such as leptin that regulates energy homeostasis. Recent developments in the field have helped to solve some of the mysteries behind lipodystrophy that allowed us to get a better understanding of adipocyte function and differentiation. From a clinical standpoint, physicians who suspect lipodystrophy should distinguish the disease from several others that may present with similar clinical features. It is also important for physicians to carefully interpret clinical features, laboratory, and imaging results before moving to more sophisticated tests and making decisions about therapy.

Comorbidities and Survival in Patients With Lipodystrophy: An International Chart Review Study

CONTEXT

Limited natural history data are available in patients with non-HIV-related lipodystrophy syndromes who never received disease-specific therapies, making interpretation of benefits of therapies in lipodystrophy syndromes challenging.

OBJECTIVE

We assessed the natural history of non-HIV-related generalized lipodystrophy (GL) and partial lipodystrophy (PL) in patients who have never received leptin or other lipodystrophy-specific therapies.

DESIGN/SETTING/PATIENTS

We conducted an international chart review of 230 patients with confirmed GL or PL at five treatment centers who never received leptin or other lipodystrophy-specific therapies. Patients were observed from birth to loss to follow-up, death, or date of chart abstraction.

OUTCOME MEASURES

Lifetime prevalence of diabetes/insulin resistance and select organ abnormalities, time to diabetes/insulin resistance, first organ abnormality, disease progression, and mortality were described.

RESULTS

Diabetes/insulin resistance was identified in 58.3% of patients. Liver abnormalities were the most common organ abnormality (71.7%), followed by kidney (40.4%), heart (30.4%), and pancreatitis (13.0%). Kaplan-Meier estimates of mean (SE) time to first organ abnormality were 7.7 years (0.9) in GL and 16.1 years (1.5) in PL (P < 0.001). Mean time to diabetes/insulin resistance was 12.7 years (1.2) in GL and 19.1 years (1.7) in PL (P = 0.131). Mean time to disease progression was 7.6 years (0.8) and comparable between GL and PL subgroups (P = 0.393). Mean time to death was 51.2 years (3.5) in GL and 66.6 years (1.0) in PL (P < 0.001).

CONCLUSIONS

This large-scale study provides comprehensive, long-term data across multiple countries on the natural history of non-HIV-related lipodystrophy.

Efficacy of Metreleptin Treatment in Familial Partial Lipodystrophy Due to PPARG vs LMNA Pathogenic Variants

CONTEXT

Familial partial lipodystrophy (FPLD) is most commonly caused by pathogenic variants in LMNA and PPARG. Leptin replacement with metreleptin has largely been studied in the LMNA group.

OBJECTIVE

To understand the efficacy of metreleptin in PPARG vs LMNA pathogenic variants and investigate predictors of metreleptin responsiveness.

DESIGN

Subgroup analysis of a prospective open-label study of metreleptin in lipodystrophy.

SETTING

National Institutes of Health, Bethesda, Maryland.

PARTICIPANTS

Patients with LMNA (n = 22) or PPARG pathogenic variants (n = 7), leptin <12 ng/mL, and diabetes, insulin resistance, or high triglycerides.

INTERVENTION

Metreleptin (0.08 to 0.16 mg/kg) for 12 months.

OUTCOME

Hemoglobin A1c (HbA1c), lipids, and medication use at baseline and after 12 months.

RESULTS

Baseline characteristics were comparable in patients with PPARG and LMNA: HbA1c, 9.2 ± 2.3 vs 7.8 ± 2.1%; median [25th, 75th percentile] triglycerides, 1377 [278, 5577] vs 332 [198, 562] mg/dL; leptin, 6.3 ± 3.8 vs 5.5 ± 2.5 ng/mL (P > 0.05). After 12 months of metreleptin, HbA1c declined to 7.7 ± 2.4 in PPARG and 7.3 ± 1.7% in LMNA; insulin requirement decreased from 3.8 [2.7, 4.3] to 2.1 [1.6, 3.0] U/kg/d in PPARG and from 1.7 [1.3, 4.4] to 1.2 [1.0, 2.3] U/kg/d in LMNA (P < 0.05). Triglycerides decreased to 293 [148, 406] mg/dL in LMNA (P < 0.05), but changes were not significant in PPARG: 680 [296, 783] mg/dL at 12 months (P = 0.2). Both groups were more likely to experience clinically relevant triglyceride (≥30%) or HbA1c (≥1%) reduction with metreleptin if they had baseline triglycerides ≥500 mg/dL or HbA1c >8%.

CONCLUSION

Metreleptin resulted in similar metabolic improvements in patients with LMNA and PPARG pathogenic variants. Our findings support the efficacy of metreleptin in patients with the two most common genetic causes of FPLD.

Fatty liver in lipodystrophy: A review with a focus on therapeutic perspectives of adiponectin and/or leptin replacement

Lipodystrophy is a group of clinically heterogeneous, inherited or acquired, disorders characterized by complete or partial absence of subcutaneous adipose tissue that may occur simultaneously with the pathological, ectopic, accumulation of fat in other regions of the body, including the liver. Fatty liver adds significantly to hepatic and extra-hepatic morbidity in patients with lipodystrophy. Lipodystrophy is strongly associated with severe insulin resistance and related comorbidities, such as hyperglycemia, hyperlipidemia and nonalcoholic fatty liver disease (NAFLD), but other hepatic diseases may co-exist in some types of lipodystrophy, including autoimmune hepatitis in acquired lipodystrophies, or viral hepatitis in human immunodeficiency virus (HIV)-associated lipodystrophy. The aim of this review is to summarize evidence linking lipodystrophy with hepatic disease and to provide a special focus on potential therapeutic perspectives of leptin replacement therapy and adiponectin upregulation in lipodystrophy.

An overview of lipodystrophy and the role of the complement system

The complement system is a major component of innate immunity playing essential roles in the destruction of pathogens, the clearance of apoptotic cells and immune complexes, the enhancement of phagocytosis, inflammation, and the modulation of adaptive immune responses. During the last decades, numerous studies have shown that the complement system has key functions in the biology of certain tissues. For example, complement contributes to normal brain and embryonic development and to the homeostasis of lipid metabolism. However, the complement system is subjected to the effective balance between activation-inactivation to maintain complement homeostasis and to prevent self-injury to cells or tissues. When this control is disrupted, serious pathologies eventually develop, such as C3 glomerulopathy, autoimmune conditions and infections. Another heterogeneous group of ultra-rare diseases in which complement abnormalities have been described are the lipodystrophy syndromes. These diseases are characterized by the loss of adipose tissue throughout the entire body or partially. Complement over-activation has been reported in most of the patients with acquired partial lipodystrophy (also called Barraquer-Simons Syndrome) and in some cases of the generalized variety of the disease (Lawrence Syndrome). Even so, the mechanism through which the complement system induces adipose tissue abnormalities remains unclear. This review focuses on describing the link between the complement system and certain forms of lipodystrophy. In addition, we present an overview regarding the clinical presentation, differential diagnosis, classification, and management of patients with lipodystrophy associated with complement abnormalities.

Long-term effectiveness and safety of metreleptin in the treatment of patients with partial lipodystrophy

PURPOSE

To evaluate the effects of metreleptin in patients with partial lipodystrophy (PL).

METHODS

Patients aged ≥ 6 months with PL, circulating leptin < 12.0 ng/mL, and diabetes mellitus, insulin resistance, or hypertriglyceridemia received metreleptin doses (once or twice daily) titrated to a mean of 0.124 mg/kg/day. Changes from baseline to month 12 in glycated hemoglobin (HbA1c) and fasting serum triglycerides (TGs; co-primary endpoints), fasting plasma glucose (FPG), and liver volume were evaluated. Additional assessments included the proportions of patients achieving target decreases in HbA1c or fasting TGs at month 12, long-term treatment effects, and treatment-emergent adverse events (TEAEs).

RESULTS

Significant (p < 0.05) reductions in HbA1c (-0.6%), fasting TGs (-20.8%), FPG (-1.2 mmol/L), and liver volume (-13.4%) were observed in the overall PL population at month 12. In a subgroup of patients with baseline HbA1c ≥ 6.5% or TGs ≥ 5.65 mmol/L, significant (p < 0.05) reductions were seen in HbA1c (-0.9%), fasting TGs (-37.4%), FPG (-1.9 mmol/L), and liver volume (-12.4%). In this subgroup, 67.9% of patients had a ≥ 1% decrease in HbA1c or ≥ 30% decrease in fasting TGs, and 42.9% had a ≥ 2% decrease in HbA1c or ≥ 40% decrease in fasting TGs. Long-term treatment in this subgroup led to significant (p < 0.05) reductions at months 12, 24, and 36 in HbA1c, fasting TGs, and FPG. Metreleptin was well tolerated with no unexpected safety signals. The most common TEAEs were abdominal pain, hypoglycemia, and nausea.

CONCLUSIONS

In patients with PL, treatment with metreleptin was well tolerated and resulted in improvements in glycemic control, hypertriglyceridemia, and liver volume.

Regional Body Fat Changes and Metabolic Complications in Children With Dunnigan Lipodystrophy-Causing LMNA Variants

CONTEXT

Familial partial lipodystrophy, Dunnigan variety (FPLD2) is a rare autosomal-dominant disorder due to heterozygous missense lamin A/C (LMNA) mutations. Subjects with FPLD2 gradually lose fat from the upper and lower extremities but gain fat in the face and neck around puberty. However, the precise onset of body fat changes and metabolic complications during childhood remains unknown.

OBJECTIVE

To compare metabolic parameters and regional body fat in children with FPLD2 with the sex- and age-matched controls from the National Health and Nutrition Examination Survey (NHANES) 2005 to 2010.

METHODS

We measured fasting serum triglycerides, glucose, and skinfold thicknesses in all children (aged 1 to 18 years) harboring FPLD2-causing LMNA mutations and determined regional body fat by dual-energy X-ray absorptiometry in those aged ≥8 years.

RESULTS

Thirty-two affected females and 14 males participated. The lower limb fat in all affected females, except one, was below or equal to the first percentile and in two affected males was below the fifth percentile for NHANES. One female subject with FPLD2 followed from age 6 to 16 years revealed marked loss of extremity fat much before thelarche. Serum triglycerides were higher in females with FPLD2 aged 7 to 18 years compared with controls (median 208 vs 70 mg/dL; P < 0.0001) and showed inverse correlation with extremity skinfolds. Serum triglycerides in males with FPLD2 were not significantly different than controls.

CONCLUSIONS

The onset of fat loss from the extremities, especially in girls with FPLD2, occurs well before the onset of puberty. High serum triglycerides are seen in young females with FPLD2 with severe loss of fat from the extremities.

A subset of patients with acquired partial lipodystrophy developing severe metabolic abnormalities

Purpose/Aim of the study: Acquired partial lipodystrophy (APL) is a rare disease characterized by selective loss of adipose tissue. In this study, we aimed to present a subset of patients with APL, who developed severe metabolic abnormalities, from our national lipodystrophy registry.

MATERIALS AND METHODS

Severe metabolic abnormalities were defined as: poorly controlled diabetes (HbA1c above 7% despite treatment with insulin more than 1 unit/kg/day combined with oral antidiabetics), severe hypertriglyceridemia (triglycerides above 500 mg/dL despite treatment with lipid-lowering drugs), episodes of acute pancreatitis, or severe hepatic involvement (biopsy-proven non-alcoholic steatohepatitis (NASH)).

RESULTS

Among 140 patients with all forms of lipodystrophy (28 with APL), we identified 6 APL patients with severe metabolic abnormalities. The geometric mean for age was 37 years (range: 27-50 years; 4 females and 2 males). Five patients had poorly controlled diabetes despite treatment with high-dose insulin combined with oral antidiabetics. Severe hypertriglyceridemia developed in five patients, of those three experienced episodes of acute pancreatitis. Although all six patients had hepatic steatosis at various levels on imaging studies, NASH was proven in two patients on liver biopsy. Our data suggested that APL patients with severe metabolic abnormalities had a more advanced fat loss and longer disease duration.

CONCLUSIONS

We suggest that these patients represent a potential subgroup of APL who may benefit from metreleptin or investigational therapies as standard treatment strategies fail to achieve a good metabolic control.

LMNA-mutated Rabbits: A Model of Premature Aging Syndrome with Muscular Dystrophy and Dilated Cardiomyopathy

Premature aging syndromes are rare genetic disorders mimicking clinical and molecular features of aging. Products of the LMNA gene, primarily lamin A and C, are major components of the nuclear lamina. A recently identified group of premature aging syndromes was related to mutations of the LMNA gene. Although LMNA disorders have been identified in premature aging syndromes, affect specifically the skeletal muscles, cardiac muscles, and lipodystrophy, understanding the pathogenic mechanisms still need to be elucidated. Here, to establish a rabbit knockout (KO) model of premature aging syndromes, we performed precise LMNA targeting in rabbits via co-injection of Cas9/sgRNA mRNA into zygotes. The LMNA-KO rabbits exhibited reduced locomotion activity with abnormal stiff walking posture and a shortened stature, all of them died within 22 days. In addition, cardiomyopathy, muscular dystrophy, bone and joint abnormalities, as well as lipodystrophy were observed in LMNA-KO rabbits. In conclusion, the novel rabbit LMNA-KO model, displayed typical features of histopathological defects that are observed in premature aging syndromes, and may be utilized as a valuable resource for understanding the pathophysiological mechanisms of premature aging syndromes and elucidating mysteries of the normal process of aging in humans.

Visceral fat does not contribute to metabolic disease in lipodystrophy

OBJECTIVES

Lipodystrophies are characterized by regional or generalized loss of adipose tissue and severe metabolic complications. The role of visceral adipose tissue (VAT) in the development of metabolic derangements in lipodystrophy is unknown. The study aim was to investigate VAT contribution to metabolic disease in lipodystrophy versus healthy controls.

METHODS

Analysis of correlations between VAT volume and biomarkers of metabolic disease in 93 patients and 93 age/sex-matched healthy controls.

RESULTS

Patients with generalized lipodystrophy (n = 43) had lower VAT compared with matched controls, while those with partial lipodystrophy (n = 50) had higher VAT versus controls. Both groups with lipodystrophy had lower leg fat mass versus controls (p < 0.05 for all; unpaired t-test). In both generalized and partial lipodystrophy, there was no correlation between VAT and glucose, triglycerides or high-density lipoprotein cholesterol (p > 0.05 for all; Spearman correlation). In controls matched to patients with generalized or partial lipodystrophy, VAT correlated with glucose (R = 0.42 and 0.36), triglycerides (R = 0.36 and 0.60) and high-density lipoprotein cholesterol (R = -0.34 and -0.64) (p < 0.05 for all; Spearman correlation).

CONCLUSIONS

In contrast to healthy controls, metabolic derangements in lipodystrophy did not correlate with VAT volume. These data suggest that, in lipodystrophy, impaired peripheral subcutaneous fat deposition may exert a larger effect than VAT accumulation on the development of metabolic complications. Interventions aimed at increasing functional subcutaneous adipose tissue may provide metabolic benefit.

Lipodystrophies, dyslipidaemias and atherosclerotic cardiovascular disease

Lipodystrophies are rare, heterogeneous, genetic or acquired, disorders characterised by varying degrees of body fat loss and associated metabolic complications, including insulin resistance, dyslipidaemias, hepatic steatosis and predisposition to atherosclerotic cardiovascular disease (ASCVD). The four main types of lipodystrophy, excluding antiretroviral therapy-induced lipodystrophy in HIV-infected patients, are congenital generalised lipodystrophy (CGL), familial partial lipodystrophy (FPLD), acquired generalised lipodystrophy (AGL) and acquired partial lipodystrophy (APL). This paper reviews the literature related to the prevalence of dyslipidaemias and ASCVD in patients with lipodystrophies. Patients with CGL, AGL and FPLD have increased prevalence of dyslipidaemia but those with APL do not. Patients with CGL as well as AGL present in childhood, and have severe dyslipidaemias (mainly hypertriglyceridaemia) and early onset diabetes mellitus as a consequence of extreme fat loss. However, only a few patients with CGL and AGL have been reported to develop coronary heart disease. In contrast, data from some small cohorts of FPLD patients reveal increased prevalence of ASCVD especially among women. Patients with APL have a relatively low prevalence of hypertriglyceridaemia and diabetes mellitus. Overall, patients with lipodystrophies appear to be at high risk of ASCVD due to increased prevalence of dyslipidaemia and diabetes and efforts should be made to manage these metabolic complications aggressively to prevent ASCVD.

Phenotypic and Genetic Characteristics of Lipodystrophy: Pathophysiology, Metabolic Abnormalities, and Comorbidities

PURPOSE OF REVIEW

This article focuses on recent progress in understanding the genetics of lipodystrophy syndromes, the pathophysiology of severe metabolic abnormalities caused by these syndromes, and causes of severe morbidity and a possible signal of increased mortality associated with lipodystrophy. An updated classification scheme is also presented.

RECENT FINDINGS

Lipodystrophy encompasses a group of heterogeneous rare diseases characterized by generalized or partial lack of adipose tissue and associated metabolic abnormalities including altered lipid metabolism and insulin resistance. Recent advances in the field have led to the discovery of new genes associated with lipodystrophy and have also improved our understanding of adipose biology, including differentiation, lipid droplet assembly, and metabolism. Several registries have documented the natural history of the disease and the serious comorbidities that patients with lipodystrophy face. There is also evolving evidence for increased mortality rates associated with lipodystrophy. Lipodystrophy syndromes represent a challenging cluster of diseases that lead to severe insulin resistance, a myriad of metabolic abnormalities, and serious morbidity. The understanding of these syndromes is evolving in parallel with the identification of novel disease-causing mechanisms.

A new type of familial partial lipodystrophy: distinctive fat distribution and proteinuria

PURPOSE

To describe an interesting subtype of familial partial lipodystrophy (FPLD).

METHODS

The phenotype of this distinctive FPLD subtype was studied in three Turkish female siblings.

RESULTS

Mutation testing was negative for the genes associated with lipodystrophy syndromes. In MRI studies, fat loss was prominent in the posterior aspects of the proximal lower limbs, whilst some fat was preserved in the anterior, medial and lateral aspects. Remarkably, fat tissue was preserved in the distal part of the limbs. Local fat accumulation was observed in the mons pubis area. Asymmetrical fat loss was also remarkable in the upper extremities. All three patients had severe insulin resistance associated with diabetes mellitus, acanthosis nigricans, hypertriglyceridemia and hepatic steatosis. Abnormal amounts of proteinuria were detected in all three subjects. Renal biopsy showed mild tubular atrophy, interstitial fibrosis, irregular thickening and wrinkling of glomerular basal membranes, small areas of segmental sclerosis and pedicel effacement.

CONCLUSIONS

We reported a form of FPLD characterized by a striking pattern of highly selective partial fat loss and proteinuria.

Pancreatic fat deposition is increased and related to beta-cell function in women with familial partial lipodystrophy

BACKGROUND

To study pancreatic fat deposition and beta-cell function in familial partial lipodystrophy (FPLD) patients.

METHODS

In a cross-sectional study, eleven patients with FPLD, and eight healthy volunteers were matched for age and body mass index and studied at a referral center. Body composition was assessed using dual-energy X-ray absorptiometry and the Dixon method of magnetic resonance imaging was used to quantify pancreatic and liver fat. Fasting plasma glucose, insulin, leptin, lipids and homeostasis model assessment of insulin resistance values were measured, and an oral glucose tolerance test was performed. The insulinogenic index, Matsuda insulin sensitivity index and beta-cell disposition index were calculated.

RESULTS

The FPLD group presented a higher waist-to-hip ratio and fat mass ratio and lower total, truncal and lower-limb fat masses. Pancreatic and liver fat contents (log transformed) were significantly higher in the FPLD group (5.26 ± 1.5 vs. 4.08 ± 0.64, p = 0.034 and 0.77 ± 0.50 vs. 0.41 ± 0.18, p = 0.056, respectively). Pancreatic fat was inversely related to the DI (r = - 0.53, p = 0.027) and HDL-cholesterol (r = - 0.63, p = 0.003) and directly related to WHR (r = 0.60; p = 0.009), HbA1c (r = 0.58; p = 0.01) and serum triglyceride (r = 0.48, p = 0.034). Higher triglyceride and lower HDL-cholesterol levels were observed in the FPLD group.

CONCLUSIONS

This study demonstrated for the first time that pancreatic fat deposition is increased in FPLD. Moreover, an inverse relationship was demonstrated between pancreatic fat and beta-cell function. The findings of this study may be consistent with the expandability hypothesis and the twin cycle hypothesis.

Renal complications of lipodystrophy: A closer look at the natural history of kidney disease

OBJECTIVES

Lipodystrophy syndromes are a group of heterogeneous disorders characterized by adipose tissue loss. Proteinuria is a remarkable finding in previous reports.

STUDY DESIGN

In this multicentre study, prospective follow-up data were collected from 103 subjects with non-HIV-associated lipodystrophy registered in the Turkish Lipodystrophy Study Group database to study renal complications in treatment naïve patients with lipodystrophy.

METHODS

Main outcome measures included ascertainment of chronic kidney disease (CKD) by studying the level of proteinuria and the estimated glomerular filtration rate (eGFR). Kidney volume was measured. Percutaneous renal biopsies were performed in 9 patients.

RESULTS

Seventeen of 37 patients with generalized and 29 of 66 patients with partial lipodystrophy had CKD characterized by proteinuria, of those 12 progressed to renal failure subsequently. The onset of renal complications was significantly earlier in patients with generalized lipodystrophy. Patients with CKD were older and more insulin resistant and had worse metabolic control. Increased kidney volume was associated with poor metabolic control and suppressed leptin levels. Renal biopsies revealed thickening of glomerular basal membranes, mesangial matrix abnormalities, podocyte injury, focal segmental sclerosis, ischaemic changes and tubular abnormalities at various levels. Lipid vacuoles were visualized in electron microscopy images.

CONCLUSIONS

CKD is conspicuously frequent in patients with lipodystrophy which has an early onset. Renal involvement appears multifactorial. While poorly controlled diabetes caused by severe insulin resistance may drive the disease in some cases, inherent underlying genetic defects may also lead to cell autonomous mechanisms contributory to the pathogenesis of kidney disease.