Familial partial lipodystrophy syndromes

Case report: First Chinese patient with family partial lipodystrophy type 6 due to novel compound heterozygous mutations in the LIPE gene

Background

Family partial lipodystrophy (FPLD) is a rare autosomal dominant disease characterized by disorders of variable body fat loss associated with metabolic complications. FPLD6 has only been reported in a limited number of cases. Here, we reported a Chinese FPLD6 patient with compound heterozygous mutations in the lipase E, hormone-sensitive type (LIPE) gene.

Case presentation

A 20-year-old female patient presented with hypertriglyceridemia, diabetes mellitus, hepatomegaly, and hepatic steatosis. Subcutaneous fat was significantly diminished in her face, abdomen, and limbs. The patient was assessed by detailed clinical and biochemical examinations. A liver biopsy showed severe lipodystrophy. In addition, there were retinal changes, peripheral nerve damage, and renal tubular injury. Sequencing was performed on extracted DNA. Genetic analysis revealed that the patient had compound heterozygous mutations in the LIPE gene: c.2497_250ldel (p.Glu833LysfsTer22) and c.2705del (p.Ser902ThrfsTer27) heterozygous mutations. Verification revealed that this mutation was inherited from her father and mother, respectively, and that they formed newly discovered compound heterozygous mutations occurring in the LIPE gene, causing FPLD6.

Conclusion

We reported the first case of FPLD6 in China. Gene analysis demonstrated compound heterozygous mutations in LIPE in this patient. Our case emphasizes the importance of genetic testing in young patients with severe metabolic syndromes.

Echocardiographic Alterations of Cardiac Geometry and Function in Patients with Familial Partial Lipodystrophy

BACKGROUND

Cardiomyopathy associated with partial lipodystrophy (PL) has not been well described yet.

OBJECTIVE

To characterize cardiac morphology and function in PL.

METHODS

Patients with familial PL and controls were prospectively assessed by transthoracic echocardiography and with speckle-tracking echocardiography (global longitudinal strain, GLS). The relationship between echocardiographic variables and PL diagnosis was tested with regression models, considering the effect of systolic blood pressure (SBP). Significance level of 5% was adopted.

RESULTS

Twenty-nine patients with PL were compared to 17 controls. They did not differ in age (p=0.94), gender or body mass index (p= 0.05). Patients with PL had statistically higher SBP (p=0.02) than controls. Also, PL patients had higher left atrial dimension (37.3 ± 4.4 vs. 32.1 ± 4.3 mm, p= 0.001) and left atrial (30.2 ± 7.2 vs. 24.9 ± 9.0 mL/m2,p=0.02), left ventricular (LV) mass (79.3 ± 17.4 vs. 67.1 ± 19.4, p=0.02), and reduced diastolic LV parameters (E' lateral, p= 0.001) (E' septal, p= 0.001), (E/E' ratio, p= 0.02). LV ejection fraction (64.7 ± 4.6 vs. 62.2 ± 4.4 %, p= 0.08) and GLS were not statistically different between groups (-17.1 ± 2.7 vs. -18.0 ± 2.0 %, p= 0.25). There was a positive relationship of left atrium (β 5.6, p<0.001), posterior wall thickness, (β 1.3, p=0.011), E' lateral (β -3.5, p=0.002) and E' septal (β -3.2, p<0.001) with PL diagnosis, even after adjusted for SBP.

CONCLUSION

LP patients have LV hypertrophy, left atrial enlargement, and LV diastolic dysfunction although preserved LVEF and GLS. Echocardiographic parameters are related to PL diagnosis independent of SBP.

A rapid action plan to improve diagnosis and management of lipodystrophy syndromes

Introduction

Lipodystrophy syndromes are rare diseases that can present with a broad range of symptoms. Delays in diagnosis are common, which in turn, may predispose to the development of severe metabolic complications and end-organ damage. Many patients with lipodystrophy syndromes are only diagnosed after significant metabolic abnormalities arise. Prompt action by clinical teams may improve disease outcomes in lipodystrophy syndromes. The aim of the Rapid Action Plan is to serve as a set of recommendations from experts that can support clinicians with limited experience in lipodystrophy syndromes.

Methods

The Rapid Action Plan was developed using insights gathered through a series of advisory meetings with clinical experts in lipodystrophy syndromes. A skeleton template was used to facilitate interviews. A consensus document was developed, reviewed, and approved by all experts.

Results

Lipodystrophy is a clinical diagnosis. The Rapid Action Plan discusses tools that can help diagnose lipodystrophy syndromes. The roles of clinical and family history, physical exam, patient and family member photos, routine blood tests, leptin levels, skinfold measurements, imaging studies, and genetic testing are explored. Additional topics such as communicating the diagnosis to the patients/families and patient referrals are covered. A set of recommendations regarding screening and monitoring for metabolic diseases and end-organ abnormalities is presented. Finally, the treatment of lipodystrophy syndromes is reviewed.

Discussion

The Rapid Action Plan may assist clinical teams with the prompt diagnosis and holistic work-up and management of patients with lipodystrophy syndromes, which may improve outcomes for patients with this rare disease.

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.

Cellular Metabolism and Bioenergetic Function in Human Fibroblasts and Preadipocytes of Type 2 Familial Partial Lipodystrophy

LMNA mutation is associated with type-2 familial partial lipodystrophy (FPLD2). The disease causes a disorder characterized by anomalous accumulation of body fat in humans. The dysfunction at the molecular level is triggered by a lamin A/C mutation, impairing the cell metabolism. In human fibroblasts and preadipocytes, a trend for ATP production, mainly supported by mitochondrial oxidative metabolism, is detected. Moreover, primary cell lines with FPLD2 mutation decrease the mitochondrial ATP production if compared with the control, even if no differences are observed in the oxygen consumption rate of bioenergetic parameters (i.e., basal and maximal respiration, spare respiratory capacity, and ATP turnover). Conversely, glycolysis is only inhibited in FPLD2 fibroblast cell lines. We notice that the amount of ATP produced in the fibroblasts is higher than in the preadipocytes, and likewise in the control, with respect to FPLD2, due to a more active oxidative phosphorylation (OXPHOS) and glycolysis. Moreover, the proton leak parameter, which characterizes the transformation of white adipose tissue to brown/beige adipose tissue, is unaffected by FPLD2 mutation. The metabolic profile of fibroblasts and preadipocytes is confirmed by the ability of these cell lines to increase the metabolic potential of both OXPHOS and glycolysis under energy required independently by the FPLD2 mutation.

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

AIM

To describe baseline characteristics and follow-up data in patients with lipodystrophy syndromes treated with metreleptin in a national reference network, in a real-life setting.

PATIENTS AND METHODS

Clinical and metabolic data from patients receiving metreleptin in France were retrospectively collected, at baseline, at 1 year and at the latest follow-up during treatment.

RESULTS

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

CONCLUSIONS

In this real-life setting study, metabolic outcomes are improved by metreleptin therapy in patients with GLD. The therapeutic indication for metreleptin needs to be clarified in patients with PLD.