Leyla Demir

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

CONTEXT Congenital generalized lipodystrophy (CGL) is a rare autosomal recessive disorder characterized by near-total lack of body fat. OBJECTIVE We aimed to study natural history and disease burden of various subtypes of CGL. DESIGN We attempted to ascertain nearly all patients with CGL in Turkey. SETTING This was a nationwide study. PATIENTS OR OTHER PARTICIPANTS Participants included 33 patients (22 families) with CGL and 30 healthy controls. MAIN OUTCOME MEASURE(S) We wanted to ascertain genotypes by sequencing of the known genes. Whole-body magnetic resonance imaging was used to investigate the extent of fat loss. Metabolic abnormalities and end-organ complications were measured on prospective follow-up. RESULTS Analysis of the AGPAT2 gene revealed four previously reported and four novel mutations (CGL1; c.144C>A, c.667_705delinsCTGCG, c.268delC, and c.316+1G>T). Analysis of the BSCL2 gene revealed four different homozygous and one compound heterozygous possible disease-causing mutations (CGL2), including four novel mutations (c.280C>T, c.631delG, c.62A>T, and c.465-468delGACT). Two homozygous PTRF mutations (c.481-482insGTGA and c.259C>T) were identified (CGL4). Patients with CGL1 had preservation of adipose tissue in the palms, soles, scalp, and orbital region, and had relatively lower serum adiponectin levels as compared to CGL2 patients. CGL4 patients had myopathy and other distinct clinical features. All patients developed various metabolic abnormalities associated with insulin resistance. Hepatic involvement was more severe in CGL2. End-organ complications were observed at young ages. Two patients died at age 62 years from cardiovascular events. CONCLUSIONS CGL patients from Turkey had both previously reported and novel mutations of the AGPAT2, BSCL2, and PTRF genes. Our study highlights the early onset of severe metabolic abnormalities and increased risk of end-organ complications in patients with CGL.

Acquired partial lipodystrophy is associated with increased risk for developing metabolic abnormalities

OBJECTIVE Acquired partial lipodystrophy (APL) is a rare disorder characterized by progressive selective fat loss. In previous studies, metabolic abnormalities were reported to be relatively rare in APL, whilst they were quite common in other types of lipodystrophy syndromes. METHODS In this nationwide cohort study, we evaluated 21 Turkish patients with APL who were enrolled in a prospective follow-up protocol. Subjects were investigated for metabolic abnormalities. Fat distribution was assessed by whole body MRI. Hepatic steatosis was evaluated by ultrasound, MRI and MR spectroscopy. Patients with diabetes underwent a mix meal stimulated C-peptide/insulin test to investigate pancreatic beta cell functions. Leptin and adiponectin levels were measured. RESULTS Fifteen individuals (71.4%) had at least one metabolic abnormality. Six patients (28.6%) had diabetes, 12 (57.1%) hypertrigylceridemia, 10 (47.6%) low HDL cholesterol, and 11 (52.4%) hepatic steatosis. Steatohepatitis was further confirmed in 2 patients with liver biopsy. Anti-GAD was negative in all APL patients with diabetes. APL patients with diabetes had lower leptin and adiponectin levels compared to patients with type 2 diabetes and healthy controls. However, contrary to what we observed in patients with congenital generalized lipodystrophy (CGL), we did not detect consistently very low leptin levels in APL patients. The mix meal test suggested that APL patients with diabetes had a significant amount of functional pancreatic beta cells, and their diabetes was apparently associated with insulin resistance. CONCLUSIONS Our results show that APL is associated with increased risk for developing metabolic abnormalities. We suggest that close long-term follow-up is required to identify and manage metabolic abnormalities in APL.

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

OBJECTIVE Familial partial lipodystrophy (FPLD) is a rare genetic disorder characterized by partial lack of subcutaneous fat. METHODS This multicenter prospective observational study included data from 56 subjects with FPLD (18 independent Turkish families). Thirty healthy controls were enrolled for comparison. RESULTS Pathogenic variants of the LMNA gene were determined in nine families. Of those, typical exon 8 codon 482 pathogenic variants were identified in four families. Analysis of the LMNA gene also revealed exon 1 codon 47, exon 5 codon 306, exon 6 codon 349, exon 9 codon 528, and exon 11 codon 582 pathogenic variants. Analysis of the PPARG gene revealed exon 3 p.Y151C pathogenic variant in two families and exon 7 p.H477L pathogenic variant in one family. A non-pathogenic exon 5 p.R215Q variant of the LMNB2 gene was detected in another family. Five other families harbored no mutation in any of the genes sequenced. MRI studies showed slightly different fat distribution patterns among subjects with different point mutations, though it was strikingly different in subjects with LMNA p.R349W pathogenic variant. Subjects with pathogenic variants of the PPARG gene were associated with less prominent fat loss and relatively higher levels of leptin compared to those with pathogenic variants in the LMNA gene. Various metabolic abnormalities associated with insulin resistance were detected in all subjects. End-organ complications were observed. CONCLUSION We have identified various pathogenic variants scattered throughout the LMNA and PPARG genes in Turkish patients with FPLD. Phenotypic heterogeneity is remarkable in patients with LMNA pathogenic variants related to the site of missense mutations. FPLD, caused by pathogenic variants either in LMNA or PPARG is associated with metabolic abnormalities associated with insulin resistance that lead to increased morbidity.

Familial partial lipodystrophy linked to a novel peroxisome proliferator activator receptor -γ (PPARG) mutation, H449L: a comparison of people with this mutation and those with classic codon 482 Lamin A/C (LMNA) mutations.

To describe the phenotype associated with a novel heterozygous missense PPARG mutation discovered in a Turkish family and to compare the fat distribution and metabolic characteristics of subjects with the peroxisome proliferator activator receptor ‐γ (PPARG) mutation with those of a cluster of patients with familial partial lipodystrophy with classic codon 482 Lamin A/C (LMNA) mutations.

Interference in ACTH immunoassay negatively impacts the management of subclinical hypercortisolism

PurposeLow plasma corticotropin is considered a useful parameter for the diagnosis of subclinical hypercortisolism in patients with an adrenal incidentaloma. However, immunoassays are vulnerable to interference from endogenous antibodies. In this study, subjects who underwent Hypothalamus-pituitary-adrenal axis evaluation for the assessment of subclinical hypercortisolism were evaluated. The objective of the study was to ascertain whether antibody interference in corticotropin immunoassay affected the diagnostic work-up and clinical decisions.MethodsThe 437 consecutive patients with incidentally discovered adrenal adenomas were included in this single centre study. Patients who had a combination of a nonsuppressed corticotropin concentration (>4.4 pmol/L) and a non-suppressed cortisol concentration after 1 mg overnight dexamethasone suppression test (>50 nmol/L) were selected. Eight eligible subjects without specific features of Cushings syndrome were identified and recruited for interference studies and follow-up. Nine controls including one patient with unilateral adrenalectomy and one patient with Cushings disease were recruited as well.MeasurementsEligible subjects and controls were subjected to hormonal tests and investigations for suspected interference. Interference studies included measurement of corticotropin on a different analytical platform, serial dilutions, polyethylene glycol precipitation and heterophilic antibody analysis. Patients were followed with clinical and laboratory parameters for a median duration of 30 (12–90) months.ResultsAntibody interference was identified in four patients. Rheumatoid factor was responsible for the interference in one patient. Clinical management of the patients was affected by the erroneous results. Interference tests were negative in control subjects.ConclusionsErroneous results associated with analytical interference negatively impacted on clinical decision making in this patient group. This should be considered particularly in conditions such as subclinical hypercortisolism which decisions depend on laboratory investigations mainly. Analytical interference could explain the high variability observed both in field measurements from patients who were expected to have lower corticotropin concentrations and in subclinical hypercortisolism prevalence reported by different studies. Many problems can be resolved by ensuring good communication between clinical and laboratory staff.

Determining residual adipose tissue characteristics with MRI in patients with various subtypes of lipodystrophy

PURPOSE We aimed to investigate residual adipose tissue with whole-body magnetic resonance imaging to differentiate between subtypes of lipodystrophy. METHODS A total of 32 patients (12 with congenital generalized lipodystrophy [CGL], 1 with acquired generalized lipodystrophy [AGL], 12 with familial partial lipodystrophy [FPLD], and 7 with acquired partial lipodystrophy [APL]) were included. RESULTS Despite generalized loss of metabolically active adipose tissue, patients with CGL1 caused by AGPAT2 mutations had a significant amount of residual adipose tissue in the scalp, earlobes, retro-orbital region, and palms and soles. No residual adipose tissue was noted particularly in the head and neck, palms and soles in CGL2 caused by BSCL2 mutations. CGL4 caused by mutations in the PTRF gene was characterized with well-preserved retro-orbital and bone marrow fat in the absence of any visible residual adipose tissue in other areas. No residual adipose tissue was observed in AGL. Despite loss of subcutaneous fat, periarticular adipose tissue was preserved in the lower limbs of patients with FPLD. Retro-orbital adipose tissue was surprisingly preserved in APL, although they lacked head and neck fat. CONCLUSION Lipodystrophies are a heterogeneous group of disorders characterized by generalized or partial loss of adipose tissue, which can be congenital or acquired. Our results suggest that residual adipose tissue characteristics can help distinguish different subtypes of lipodystrophy.

Partial lipodystrophy of the limbs in a diabetes clinic setting

OBJECTIVE Partial lipodystrophy of the limbs (PLL) is a newly described form of lipodystrophy that is characterized by symmetrical distal lipoatrophy of the limbs and insulin resistant diabetes. RESEARCH DESIGN AND METHODS In this study, we prospectively screened our patients with type 2 diabetes for the presence of PLL phenotype. Metabolic parameters of PLL patients were compared to those with type 2 diabetes who applied to our diabetes clinic during the same period of time. RESULTS Between Sep 2013 and Mar 2015, 2020 patients with type 2 diabetes were evaluated for the presence of PLL. PLL was confirmed in 16 patients. The prevalence of PLL was calculated as 0.79% in our diabetes clinic. The most common phenotypic presentations were loss of subcutaneous fat in the forearms, calves and thighs, and loss of fat in forearms and calves. Patients with PLL had poor metabolic control and marked insulin resistance compared to subjects with type 2 diabetes. Diabetes had been diagnosed at a younger age in patients with PLL. Patients with PLL also had more atherogenic lipid profiles. CONCLUSIONS Our data suggests that PLL is a relatively common form of lipodystrophy in diabetes clinics, which is associated with poor metabolic control and marked insulin resistance. The recognition of PLL in patients with type 2 diabetes can help better clinical management by alerting the physician to these associated co-morbidities.