Genetics of Lipodystrophy: Can It Help in Understanding the Pathophysiology of Metabolic Syndrome?

Lipoatrophic diabetes in familial partial lipodystrophy type 2: From insulin resistance to diabetes

AIM

Subjects with Familial Partial Lipodystrophy type 2 (FPLD2) are at high risk to develop diabetes. To better understand the natural history and variability of this disease, we studied glucose tolerance, insulin response to an oral glucose load, and metabolic markers in the largest cohort to date of subjects with FPLD2 due to the same LMNA variant.

METHODS

A total of 102 patients aged > 18 years, with FPLD2 due to the LMNA 'Reunionese' variant p.(Thr655Asnfs*49) and 22 unaffected adult relatives with normal glucose tolerance (NGT) were enrolled. Oral Glucose Tolerance Tests (OGTT) with calculation of derived insulin sensitivity and secretion markers, and measurements of HbA1c, C-reactive protein, leptin, adiponectin and lipid profile were performed.

RESULTS

In patients with FPLD2: 65% had either diabetes (41%) or prediabetes (24%) despite their young age (median: 39.5 years IQR 29.0-50.8) and close-to-normal BMI (median: 25.5 kg/m² IQR 23.1-29.4). Post-load OGTT values revealed insulin resistance and increased insulin secretion in patients with FPLD2 and NGT, whereas patients with diabetes were characterized by decreased insulin secretion. Impaired glucose tolerance with normal fasting glucose was present in 86% of patients with prediabetes. Adiponectin levels were decreased in all subjects with FPLD2 and correlated with insulin sensitivity markers.

CONCLUSIONS

OGTT reveals early alterations of glucose and insulin metabolism in patients with FPLD2, and should be systematically performed before excluding a diagnosis of prediabetes or diabetes to adapt medical care. Decreased adiponectin is an early marker of the disease. Adiponectin replacement therapy warrants further study in FPLD2.

The common pathophysiologic threads between Asian Indian diabetic's 'Thin Fat Phenotype' and partial lipodystrophy: the peripheral adipose tissue transcriptomic evidences

T2D is a complex disease with poorly understood mechanisms. In Asian Indians, it is associated with “thin fat” phenotype which resembles with partial lipodystrophy. We hypothesized that disturbed expression of lipodystrophy genes might play a role in T2D pathogenesis. Therefore, we attempted to establish a link between these two diseases by studying the overlap between the network of lipodystrophy genes and the differentially expressed genes (DEGs) in the peripheral subcutaneous adipose tissue of Asian Indians diabetics. We found that 16, out of 138 lipodystrophy genes were differentially regulated in diabetics and around 18% overlap between their network and the DEGs; the expression level of lipodystrophy genes showed an association with disease-related intermediate phenotypic traits among diabetics but not in the control group. We also attempted to individualize the diabetic patients based on ±2 fold altered expression of lipodystrophy genes as compared to their average expression in the control group. In conclusion, significant overlap exists between some of the lipodystrophy genes and their network with DEGs in the peripheral adipose tissue in diabetics. They possibly play a role in the pathogenesis of diabetes and individualization of diabetics is possible based on their altered expression in their peripheral adipose tissue.