Monogenic forms of insulin resistance: apertures that expose the common metabolic syndrome

Insulin resistance is common and plays a central role in the pathogenesis of type 2 diabetes mellitus (T2DM). Precedents in biomedical research indicate that evaluation of monogenic syndromes can help to understand a common complex phenotype. Monogenic forms of insulin resistance, such as familial partial lipodystrophy, which results from mutations in either LMNA (encoding lamin A/C) or PPARG (encoding peroxisome proliferator-activated receptor gamma), and congenital generalized lipodystrophy, which results from mutations in either AGPAT2 (encoding 1-acylglycerol-3-phosphate O-acyltransferase) or BSCL2 (encoding seipin), can display features seen in the common metabolic syndrome. In addition, insulin resistance is seen in disorders associated with insulin receptor mutations, progeria syndromes and in inherited forms of obesity. Although insulin resistance in such rare monogenic syndromes could simply be secondary to fat redistribution and/or central obesity, the products of the causative genes might also produce insulin resistance directly, and might illuminate new causative mechanisms for insulin resistance in such common disorders as T2DM and obesity.

Membranous lipodystrophy

Membranous lipodystrophy (ML) is a rare hereditary disorder of adipose tissue characterized by polycystic bone lesions and progressive dementia. We describe the case of a 36-year-old woman with mechanical bone pain. Routine laboratory analyses revealed only a type IV hyperlipoproteinemia and hyperexcretion of urinary calcium. Roentgenograms of short and long bones showed symmetrical, well-defined, non-expansile cystic lesions. Bone biopsy found a yellow lipid-like substance in the osteolytic lesions and histopathological studies were non-specific. Neuropsychiatric examination, including cranial computerized tomography (CT), was found to be normal. According to clinical, analytical, radiological and histological findings ML was the diagnosis. No previous cases of ML have been reported in our country as we review the literature concerning this disease.

Meeting notes from the 2nd International AIDS Society Conference on HIV Pathogenesis and Treatment. Metabolic update: better defining lipodystrophy and treating insulin resistance

A large case-control study finds that lipoatrophy is the predominant fat abnormality in HIV-infected patients, and a small randomized, placebo-controlled study finds benefit for rosiglitazone for insulin resistance.

Lack of mutations in LMNA, its promoter region, and the cellular retinoic acid binding protein II (CRABP II) in HIV associated lipodystrophy

Familial partial lipodystrophy (FPL) and lipodystrophy observed in HIV-1 infected patients receiving highly active antiretroviral therapy (HAART) share multiple clinical and metabolic features. Recently, missense mutations of LMNA encoding lamin A/C have been described in FPL providing evidence for a pivotal role of lamin A/C in the regulation of adipocytes. Moreover, the cellular retinoic acid binding protein (CRABP) has been suggested to be involved in HAART associated lipodystrophy. In this study, we excluded mutations within the complete coding region and the promoter of LMNA and the CRABP II gene in HIV-1 infected patients with lipodystrophy and also any correlation of the nucleotide polymorphism at codon 566 in exon 10 of LMNA with metabolic abnormalities. Protease inhibitors including indinavir have been shown to reduce adipocyte cell differentiation and increase apoptosis of adipocytes in vitro. Indinavir leads to altered retinoic acid signaling most likely by an activation of the RAR/RXR heterodimer, perhaps by displacing all-trans-retinoic acid from CRABP. Since LMNA is regulated by a retinoic acid responsive element (L-RARE) in the promoter region, we propose that indinavir impairs retinoic acid homeostasis and/or interact via the L-RARE within the LMNA promoter. This results in altered LMNA expression and subsequent impaired adipocyte differentiation, lipodystrophic body habitus, and metabolic disturbances in HIV infected patients receiving HAART.

Risk factors for diabetes in familial partial lipodystrophy, Dunnigan variety

OBJECTIVES

Familial partial lipodystrophy, Dunnigan variety (FPLD), is an autosomal dominant disorder due to missense mutations in the lamin A/C (LMNA) gene encoding nuclear lamina proteins. It is characterized by loss of subcutaneous fat from the extremities and trunk and accumulation of fat in the head and neck region beginning at puberty. Patients with FPLD are predisposed to metabolic complications of insulin resistance such as diabetes. We sought to identify risk factors for diabetes in patients with FPLD.

RESEARCH DESIGN AND METHODS

A cross-sectional study comparing clinical, biochemical, and anthropometric variables and LMNA genotypes in FPLD patients with and without diabetes.

RESULTS

We studied 52 women and 24 men with FPLD from 18 different families. Twenty-eight women (54%) but only four men (17%) had diabetes (P < 0.001); therefore further comparisons were mostly limited to women. Compared with women without diabetes, those with diabetes had higher BMI (median values 23 vs. 24 kg/m(2), respectively; P = 0.03), increased chin skinfold thickness (10 vs. 20 mm; P = 0.001), lower rates of nulliparity (60% vs. 28%; P = 0.04), and higher levels of fasting serum triglycerides (2.4 vs. 3.5 mmol/l; P < 0.001) but similar serum leptin levels (3.4 vs. 3.6 ng/ml; P = 0.9). The prevalence of diabetes was not related to age, menopausal status, family history of type 2 diabetes in unaffected relatives, or LMNA genotype.

CONCLUSIONS

We conclude that increased adiposity as reflected by excess subcutaneous fat accumulation in the chin region and parity may predispose women with FPLD to develop diabetes.

[Partial lipodystrophy in two HLA identical sisters with hypocomplementemia and nephropathy]

Partial lipodystrophy is a rare disorder with both autosomal recessive and familial forms. The cutaneous findings, which are often subtle, consist of gradual loss of subcutaneous fat from the face and upper body. Low levels of C3 and the presence of C3NeF help to identify these patients. Associated systemic abnormalities include the development of membranoproliferative glomerulonephritis, insulin resistance and an increased incidence of autoimmune diseases. We report here two HLA identical sisters with the typical features of partial lipodystrophy associated with recurrent infections, low levels of C3, and nephropathy. Our data suggest an autosomal recessive transmission. We discuss the genetic and molecular basis of this rare association.

Insulin resistance and hypertension in the absence of subcutaneous fat

When a patient presents with insulin resistance, a red flag for cardiovascular risk appears. What is the contribution of visceral fat to this syndrome? What are the risks and benefits of the treatment options for the coexistent cardiovascular risk factors?

Inhibition of lipolysis improves insulin sensitivity in protease inhibitor-treated HIV-infected men with fat redistribution

BACKGROUND

Fatty acid concentrations are increased in patients with HIV and fat redistribution and may contribute to insulin resistance in this population.

OBJECTIVE

We determined the effects of acute inhibition of lipolysis on insulin sensitivity in HIV-infected patients with fat redistribution who were receiving a protease inhibitor.

DESIGN

Seven HIV-infected men [age: 45 +/- 2 y; body mass index (in kg/m(2)): 28.8 +/- 1.9] with a fasting insulin concentration > or= 104 pmol/L (15 micro IU/mL), combined visceral adiposity and peripheral lipoatrophy, and receiving a protease inhibitor were studied. Tolbutamide-modified frequently sampled intravenous-glucose-tolerance tests (FSIGTTs) were performed after randomized double-blind administration of acipimox (500 mg at -90 and 0 min), a potent inhibitor of lipolysis, and placebo. The subjects completed 2 FSIGTTs separated by 3-7 d.

RESULTS

At baseline, fasting insulin and fatty acid concentrations were 27.6 +/- 5.0 micro IU/mL and 0.83 +/- 0.08 mmol/L (normal range: 0.1-0.6 mmol/L), respectively. Fatty acid concentrations were significantly reduced after acipimox compared with placebo (fatty acid area under the curve: acipimox = 73 +/- 8 compared with placebo = 122 +/- 12 mmol x 270 min/L, P = 0.002). Acipimox treatment resulted in a significant increase in the insulin sensitivity index (acipimox = 1.63 +/- 0.5 compared with placebo = 0.88 +/- 0.3 x 10(-4) x min(-1) x micro IU/mL, P = 0.015).

CONCLUSIONS

Acute inhibition of lipolysis and reduction in fatty acid concentrations are associated with improved insulin sensitivity in patients with HIV lipodystrophy and hyperinsulinemia. Further studies are needed to determine whether long-term antilipolytic strategies to reduce fatty acid concentrations may be useful in treating the metabolic disturbances associated with HIV lipodystrophy.

Reduction of fat accumulation and lipid disorders by individualized light aerobic training in human immunodeficiency virus infected patients with lipodystrophy and/or dyslipidemia

BACKGROUND

The management of abdominal fat accumulation and metabolic disorders in HIV1-infected patients, by an aerobic training program, is considered.

METHODS

Seventeen lipodystrophic and 2 dyslipidemic (without body modification) adults were studied before and after 4 months of training. The training load was individualized on a ventilatory threshold basis, determined during a maximal exercise test on cycle ergometer. Total (TAT), Visceral (VAT) and Subcutaneous Adipose Tissue (SAT) were assessed by CT-scan. Total (TC) and High Density Lipoprotein (HDL-C) Cholesterol, Triglycerides (TG), lactate (La), insulin and glucose were measured after a 12-hour-overnight fast. LDL, TC/HDL, TG/HDL, HOMA-insulin resistance index and coronary heart disease (CHD) relative risk (RR(CHD)) were calculated.

RESULTS

Besides a significant improvement of aerobic fitness, trained patients exhibited a reduction in TAT (-12.8%, p < 0.001), specially at the visceral level (- 12%, p < 0.01) and in TC, TG and La (- 23%, - 43% and - 19% respectively, p < 0.01). HDL-C was increased (+ 6%, p < 0.01). All these effects were above changes that could be expected by a possible regression to the mean artefact. Both TC/HDL and TG/HDL were reduced (p < 0.01) and the estimated RR(CHD) decreased by approximately 13% (p < 0.01). No significant training effect was observed on the 9 available HOMAs. Significant correlations were found between changes in blood lipid values and baseline measures (r range - 0.55 to - 0.79, p < 0.05), indicating a larger improvement when baseline lipid parameters were higher.

CONCLUSION

Aerobic training reduced visceral fat, lipid disorders, basal blood lactate and CHD markers in HIV patients. Training effects were particularly important for patients with marked dyslipidemia.

Clinical review 153: Lipodystrophy in human immunodeficiency virus-infected patients

Human immunodeficiency virus (HIV) infection is a major global health problem. Recently, combination therapy including HIV-1 protease inhibitors (PIs) has dramatically improved the long-term survival of HIV-infected patients. However, such therapy is associated with a lipodystrophy syndrome characterized by selective loss of sc fat from the face and extremities and, in some patients, accumulation of fat around the neck, dorsocervical region, abdomen, and trunk. Lipodystrophy in HIV-infected patients (LDHIV) is associated with insulin resistance and its metabolic complications such as impaired glucose tolerance, diabetes, hypertriglyceridemia and low serum high density lipoprotein cholesterol levels. PIs appear to be the strongest link to LDHIV; however, fat loss has been reported in some patients taking non-PI antiretroviral drugs. Other factors, such as duration of HIV infection, age, and gender, may also contribute to the risk of development of LDHIV. The molecular basis of LDHIV remains unknown. There is no specific therapy for LDHIV. Avoiding weight gain by reducing energy intake and increasing physical activity may be beneficial in reducing fat accumulation as well as improving metabolic complications. Antihyperglycemic drugs may be used to treat diabetes. Management of dyslipidemia may require lipid-lowering drugs; however, the safety and efficacy of such intervention require further studies. Substitution of PIs with other antiretroviral drugs can mitigate dyslipidemia and glucose intolerance, but whether reversal of lipodystrophy occurs remains unknown. Future research is needed to discover the biochemical and molecular markers of lipodystrophy in HIV patients and develop PIs or other antiretroviral agents that are free of metabolic toxicity.

Partial lipodystrophy in a patient with systemic lupus erythematosus

A 54-year-old woman developed partial lipodystrophy on the left side of her face. She had been suffering from systemic lupus erythematosus (SLE) since 1985 when she was 45 years old, and she had been treated with 30 mg/day of oral prednisolone as an initial dose. Partial lipodystrophy appeared on her left lower jaw in 1994 when the SLE was inactive, and the dose of prednisolone was reduced to 5 mg/ 3 days. Gradually, the lipodystrophy spread toward her left cheek and her left forehead without any preceding skin symptoms. Histological examination showed a loss of fat tissue and mild lymphocytic infiltrations mainly around cutaneous appendages and vessels in the dermis and subcutaneous tissue. The dose of prednisolone was increased to 10 mg/day and the lesions stopped spreading. Such partial lipodystrophy is distinct from lipoatrophy of lupus profundus.

[Facial lipodystrophy in patients with HIV infections troublesome to treat]

HIV-infection is now a treatable chronic disease. The lipodystrophy syndrome, which is a common complication of treatment, is characterized by peripheral lipoatrophy, central lipohypertrophy, hyperlipidemia and insulin resistance. The underlying mechanisms are still poorly understood, but the combination of protease inhibitors with nucleoside analogs seems to induce complicated metabolic disturbances. From the patient's point of view, facial atrophy is the most stigmatizing aspect of the syndrome and might badly influence treatment adherence, crucial for long term antiviral efficacy. We propose a topographical classification and grading of facial lipoatrophy, and describe local treatment with injectable hyaluronic acid in gel form. The problem with such injections is their high cost. Since hyaluronic acid injections are not covered by the usual government subsidy for prescription medicines, ways of financing such treatments should be sought.

Lamin A/C mutations with lipodystrophy, cardiac abnormalities, and muscular dystrophy

Mutations in the lamin A/C gene are found in Emery-Dreifuss muscular dystrophy, limb girdle muscular dystrophy with cardiac conduction disturbances, dilated cardiomyopathy with conduction system disease, and familial partial lipodystrophy. Cases with lamin A/C mutations presenting with lipodystrophy in combination with cardiac and/or skeletal muscle abnormalities are described.

Analysis of paradoxical observations on the association between leptin and insulin resistance

Obesity is commonly associated with the development of insulin resistance and diabetes in humans and rodents. Insulin resistance and diabetes are observed in lipoatrophic individuals or rodent models of lipoatrophy. Here we focus on the role of leptin, the product of the obesity (ob) gene, in the development of insulin resistance and diabetes associated with obesity and lipoatrophy. We review the reported effects of leptin on whole body glucose metabolism and compare and contrast these with direct effects on skeletal muscle, fat and liver. This summary of paradoxical observations on the effects of leptin on glucose homeostasis and the ability of leptin to induce or improve insulin resistance suggests that a complex interplay exists between direct peripheral and centrally mediated effects of the hormone. Evidence suggesting that leptin acts as a mediator of insulin release from pancreatic beta cells is reviewed. Finally, intracellular signaling mechanisms stimulated by both leptin and insulin are discussed, with potential points of cross-talk suggested.

Abacavir substitution for nucleoside analogs in patients with HIV lipoatrophy: a randomized trial

CONTEXT

Peripheral lipoatrophy may complicate antiretroviral therapy of human immunodeficiency virus (HIV) infection, often related to duration and type of nucleoside analog therapy, and may have a mitochondrial pathogenesis. No proven therapy exists for lipoatrophy, but abacavir is a nucleoside analog that may be less toxic to mitochondria.

OBJECTIVE

To determine if substitution of stavudine or zidovudine with abacavir improves HIV lipoatrophy without affecting control of HIV replication.

DESIGN

Randomized, open-label 24-week study.

SETTING

Seventeen hospital HIV outpatient clinics and primary care centers in Australia and England, with randomization from June 2000 through January 2001.

PARTICIPANTS

A total of 111 adults (109 men) with moderate or severe lipoatrophy who were receiving stavudine (n = 85) or zidovudine (n = 26) and had stable plasma HIV RNA levels below 400 copies/mL and no prior abacavir therapy.

INTERVENTION

Patients were randomly assigned to switch from stavudine or zidovudine to abacavir, 300 mg twice per day, while continuing all other antiretroviral therapy (n = 54) or to continue all antiretroviral therapy (n = 57).

MAIN OUTCOME MEASURES

The primary end point was limb fat mass, measured by dual-energy x-ray absorptiometry; key secondary end points were plasma HIV RNA levels, adverse events, physician-assessed (via subjective measures) lipodystrophy severity, total and central fat mass, and fasting metabolic (lipid, glycemic, and lactate) levels.

RESULTS

There was a significant increase in limb fat in the abacavir group relative to the stavudine/zidovudine group (0.39 vs 0.08 kg; mean difference, 0.31; 95% confidence interval [CI], 0.06-0.57 kg), as well as significant relative increases in subcutaneous thigh (P =.01), arm (P<.001), and abdominal (P =.001) fat areas on computed tomography. Switching had no significant effect on secondary end points, including plasma HIV RNA (for unadjusted comparison between groups at week 24, odds ratio, 1.38; 95% CI, 0.48-3.96). Change in limb fat mass at week 24 did not correlate with change in subjectively determined perceived lipoatrophy severity (r = -0.06; P =.53 by Spearman correlation). Hypersensitivity to abacavir was seen in 5 patients (10%).

CONCLUSIONS

In this sample of lipoatrophic HIV-infected adults, switching from stavudine or zidovudine to abacavir for 24 weeks led to significant, albeit modest, objectively measured increases in limb fat. Clinical lipoatrophy, as assessed subjectively, did not resolve, however, and at the rate of increase observed may take years to resolve with use of this strategy. Longer-term follow-up is needed.

Familial partial lipodystrophy

The lipodystrophies are rare disorders characterized by insulin resistance and the absence or loss of body fat. The 4 subtypes of lipodystrophy are characterized by onset and distribution. Partial lipodystrophy is rare, with loss of fat from the extremities and excess fat accumulation in the face and neck; recognizing this phenotype and subsequent referral for endocrinologic care may improve outcome and reduce mortality.

Reduced intravertebral bone marrow fat in HIV-infected men

OBJECTIVE

To measure intravertebral bone marrow fat in HIV-infected men.

DESIGN

A cross-sectional study of HIV-positive men, subcategorized by lipodystrophy and antiretroviral status, and healthy age- and body mass index (BMI)-matched HIV-negative controls.

SETTING

A tertiary care academic medical institution.

PATIENTS

Fifteen HIV-infected men and nine age- and BMI-matched healthy control subjects were recruited for bone density, intravertebral bone marrow fat, and body composition measurements.

METHODS

Magnetic resonance spectroscopy was used to measure intravertebral marrow fat. Quantitative computed tomography was used to quantify visceral and subcutaneous fat. Dual energy X-ray absorptiometry was used to determine lumbar spine bone density. Statistical comparisons were performed according to HIV, lipodystrophy, and protease inhibitor (PI) exposure status.

RESULTS

Intravertebral marrow fat was reduced in HIV-infected men (N = 15) compared with healthy HIV-negative controls (N = 9) (28.5 +/- 8.0 versus 37.3 +/- 12.5%, P = 0.04). Intravertebral bone marrow fat was most severely reduced in HIV-infected men with lipodystrophy compared with healthy HIV-negative controls (25.6 +/- 8.8% versus 37.3 +/- 12.5%, P = 0.04). Furthermore, nelfinavir (P = 0.02) was associated with decreased intravertebral marrow fat and indinavir (P < 0.05) was associated with increased intravertebral marrow fat in HIV-infected subjects.

CONCLUSION

We demonstrated reduced intravertebral marrow fat in HIV-infected men using magnetic resonance spectroscopy. Notably, reduced marrow fat occurred in the setting of reduced bone density and may be affected by specific PI and lipodystrophy status. Further studies are necessary to determine the relationship between marrow fat and osteopenia and the effect of antiretroviral therapy on marrow fat in this population.

Clinical, endocrine and metabolic studies in the kindred of familial partial lipodystrophy--a syndrome of insulin resistance

OBJECTIVE

To study clinical, endocrine and metabolic profiles in the kindred of subjects with familial partial lipodystrophy (FPLD, Dunnigan type).

MATERIAL AND METHODS

Twenty two relatives (10 males, 12 females), from an extended family with FPLD, were assessed for the phenotypic features, impaired glucose tolerance (IGT)/diabetes mellitus (DM), dyslipidemia and the presence of insulin resistance. Plasma glucose and serum lipids were measured using glucose oxidase and standard colorimetric methods. Serum insulin was estimated by radioimmunoassay.

RESULTS

The age was 12 to 67 years, two being adolescents. Two of the 20 adults were overweight and eight were underweight; BMI (adults) was 15.5 to 28.5. Features of FPLD were evident among eight out of 12 women. This typical phenotype was not obvious in all 10 male members. Varying degree of Hirsuitism was observed in four of 12 women, acanthosis nigricans in 11 out of 22 members and skin tags were present in only eight of 22; hypertension in six members and diabetes in four. Eleven members had either impaired glucose tolerance (IGT) (n=7), or DM (n=4). Ten of 20 members showed hyperinsulinemic response on oral glucose tolerance test (OGTT). Dyslipidemia was present in 13 family members.

CONCLUSION

The majority (2/3rd) of female members showed typical phenotypic features of FPLD, with a clustering of cardiovascular risk factors and insulin resistance syndrome. More than half the men without phenotypic features of FPLD had either IGT/DM, dyslipidemia, hypertension or cardiovascular disease.

Leptin reverses insulin resistance and hepatic steatosis in patients with severe lipodystrophy

Lipodystrophy is a rare disorder that is characterized by selective loss of subcutaneous and visceral fat and is associated with hypertriglyceridemia, hepatomegaly, and disordered glucose metabolism. It has recently been shown that chronic leptin treatment ameliorates these abnormalities. Here we show that chronic leptin treatment improves insulin-stimulated hepatic and peripheral glucose metabolism in severely insulin-resistant lipodystrophic patients. This improvement in insulin action was associated with a marked reduction in hepatic and muscle triglyceride content. These data suggest that leptin may represent an important new therapy to reverse the severe hepatic and muscle insulin resistance and associated hepatic steatosis in patients with lipodystrophy.

Serum adiponectin and leptin levels in patients with lipodystrophies

Lipodystrophies are characterized by selective but variable loss of body fat and metabolic complications of insulin resistance. We hypothesized that reduced synthesis and secretion of adipocyte-specific proteins may be related to the metabolic complications of lipodystrophy. Therefore, we compared fasting serum concentrations of adiponectin and leptin, in 18 patients with congenital generalized lipodystrophy (CGL), 11 with acquired generalized lipodystrophy (AGL), 46 with familial partial lipodystrophy-Dunnigan variety (FPLD) and 18 with acquired partial lipodystrophy (APL) and studied their relationship to metabolic parameters. Patients with CGL and AGL had markedly reduced serum adiponectin levels compared to those with FPLD and APL (median [range]: 1.5 [0.4-7.5], 3.2 [0.6-7.7], 6.9 [1.9-23.2] and 7.9 [3.1-13.3] microg/mL, respectively, p < 0.0001); the same trend was noted for serum leptin levels (0.63 [0.05-3.7], 2.18 [0.05-11.30], 2.86 [0.23-9.00] and 6.24 [1.21-10.4] ng/mL, respectively, p < 0.0001). Serum adiponectin levels correlated negatively with fasting serum triglycerides (r = -0.6, p < 0.001) and insulin levels (r = -0.5, p < 0.0001) and positively with serum high-density lipoprotein cholesterol levels (r = 0.5, p < 0.001). Serum adiponectin levels were lower in patients with diabetes compared to non-diabetic subjects (3.0 vs. 7.1 microg/mL, p < 0.001). Our results indicate that serum adiponectin and leptin levels are extremely low in patients with generalized lipodystrophies and may be related to severe insulin resistance and its metabolic complications in lipodystrophies.

Paracardial lipodystrophy versus pericardial effusion in HIV positive patients

OBJECTIVE

To present an epicardial manifestation of the lipodystrophy syndrome, a side effect of antiretroviral treatment in HIV positive patients, which illustrates the important danger of false diagnosis.

PATIENT

A 52 year old man with HIV (stage C3), diagnosed 10 years previously, was being treated with a combination of nelfinavir, nevirapine, and stavudine. Echocardiographic examination showed a low echogenic pericardial space that had increased from 4 mm to 18 mm over a 10 month period. The diagnosis of paracardial adipose tissue was verified by magnetic resonance tomography. Doppler echocardiographic parameters were not significantly altered (ratio of early to late ventricular filling 0.88 v 0.73, Tei index 0.30 v 0.36).

CONCLUSION

Even a pericardial manifestation of lipodystrophy causes negligible functional impairment, misinterpretation of the lipodystrophy as a pericardial effusion and a subsequent puncture can have serious complications. Hence, it is strongly suggested that further differential diagnosis be used for HIV positive patients with an echocardiographic suspicion of pericardial effusion. Differential diagnosis by magnetic resonance tomography is possible.

Cardiomyopathy in congenital complete lipodystrophy

Molecular genetic studies have pointed to a relationship between congenital lipodystrophy syndromes and some cardiac disorders. For instance, mutations in LMNA cause either lipodystrophy or cardiomyopathy, indicating that different mutations in the same gene can produce these clinical syndromes. The present authors describe a 10-year-old female with Berardinelli-Seip congenital complete lipodystrophy (MIM 606158) caused by homozygosity for a frameshift mutation in BSCL2. In addition to the typical attributes of complete lipodystrophy, this subject had hypertrophic cardiomyopathy diagnosed in the first year of her life; its progress has been followed with non-invasive imaging. The mechanism underlying the hypertrophic cardiomyopathy in complete lipodystrophy is unclear. It may result from a direct effect of the mutant gene or it might be secondary to the effects of hyperinsulinemia on cardiac development. The variability of the associated cardiomyopathy in patients with complete generalized lipodystrophy may be caused by differential effects of mutations in the same gene or of mutations in different genes which underlie the lipodystrophy phenotype.

Osteonecrosis of the femoral head in a human immunodeficiency virus type 1-infected patient with lipodystrophy

Osteonecrosis of the femoral head is rare in human immunodeficiency virus (HIV)-infected patients. We describe a 37-year-old HIV-infected man who developed lipodystrophy after highly active antiretroviral therapy (HAART), leading to left leg disability. Radiography revealed osteonecrosis of the left femoral head, which appeared to be related to the antiretroviral therapy for HIV infection and subsequent development of lipodystrophy and hyperlipidemia. While osteonecrosis among Taiwanese HIV-infected patients is uncommon, the potential for the development of this long-term complication should be carefully monitored as more patients survive for longer periods after HAART.

Identifying and managing morphologic complications of HIV and HAART

Morphologic complications continue to be observed in patients receiving HAART. Body habitus changes include fat accumulation, lipoatrophy, and HIV-associated wasting. Anthropometry, dual-energy x-ray absorptiometry, and imaging methods (CT, MRI) are most useful for detecting fat redistribution syndromes, while bioelectric impedance analysis is useful for determining and monitoring wasting. Various clinical interventions, including diet and exercise, switching antiretroviral agents, the use of lipid-lowering and insulin-sensitizing agents, recombinant human growth hormone therapy, and plastic surgery, are under investigation for the treatment of morphologic changes. Prospective, controlled clinical trials are needed to determine the long-term efficacy of these approaches.

Leptin-replacement therapy for lipodystrophy

BACKGROUND

The adipocyte hormone leptin is important in regulating energy homeostasis. Since severe lipodystrophy is associated with leptin deficiency, insulin resistance, hypertriglyceridemia, and hepatic steatosis, we assessed whether leptin replacement would ameliorate this condition.

METHODS

Nine female patients (age range, 15 to 42 years; eight with diabetes mellitus) who had lipodystrophy and serum leptin levels of less than 4 ng per milliliter (0.32 nmol per milliliter) received recombinant methionyl human leptin (recombinant leptin). Recombinant leptin was administered subcutaneously twice a day for four months at escalating doses to achieve low, intermediate, and high physiologic replacement levels of leptin.

RESULTS

During treatment with recombinant leptin, the serum leptin level increased from a mean (+/- SE) of 1.3 +/- 0.3 ng per milliliter to 11.1 +/- 2.5 ng per milliliter (0.1 +/- 0.02 to 0.9 +/- 0.2 nmol per milliliter). The absolute decrease in the glycosylated hemoglobin value was 1.9 percent (95 percent confidence interval, 1.1 to 2.7 percent; P=0.001) in the eight patients with diabetes. Four months of therapy decreased average triglyceride levels by 60 percent (95 percent confidence interval, 43 to 77 percent; P<0.001) and liver volume by an average of 28 percent (95 percent confidence interval, 20 to 36 percent; P=0.002) in all nine patients and led to the discontinuation of or a large reduction in antidiabetes therapy. Self-reported daily caloric intake and the measured resting metabolic rate also decreased significantly with therapy. Overall, recombinant leptin therapy was well tolerated.

CONCLUSIONS

Leptin-replacement therapy improved glycemic control and decreased triglyceride levels in patients with lipodystrophy and leptin deficiency. Leptin deficiency contributes to the insulin resistance and other metabolic abnormalities associated with severe lipodystrophy.

Reduction of abdominal obesity in lipodystrophy associated with human immunodeficiency virus infection by means of diet and exercise: case report and proof of principle

Lipodystrophy associated with human immunodeficiency virus infection causes abdominal fat gain, peripheral subcutaneous fat atrophy, insulin resistance, low levels of high-density lipoprotein cholesterol, and hypertriglyceridemia. An exercise program combined with a moderate-fat, low-glycemic-index, high-fiber diet can reverse several aspects of lipodystrophy, and, until specific treatment is available, should be considered for treatment of lipodystrophy.

Methods of assessing body shape and composition in HIV-associated lipodystrophy

Although HIV-associated lipodystrophy can be diagnosed just from clinical examination, criteria for diagnosis and judgement of severity are not clearly defined. Clinical assessment can be systematized with questionnaires for patients and physicians. Computed tomography, nuclear magnetic imaging and dual-energy X-ray absorptiometry are objective reference methods but are expensive for routine follow-up and diagnosis. Therefore, anthropometry and other non-invasive bedside methods deserve further validation studies.

Elevated concentrations of free fatty acids are associated with increased insulin response to standard glucose challenge in human immunodeficiency virus-infected subjects with fat redistribution

Fat redistribution, defined by both increased abdominal visceral fat and/or decreased abdominal, extremity, and facial subcutaneous fat, is increasingly recognized among human immunodeficiency virus (HIV)-infected patients treated with combination antiretroviral therapy. Fat redistribution in this population is associated with insulin resistance and dyslipidemia and is often referred to as the HIV lipodystrophy syndrome (LIPO). Fatty acids are known to modulate insulin resistance in other disease states, but a comprehensive evaluation of fatty acids has not been undertaken among HIV-infected patients with fat redistribution. In this study, we investigated fatty acid concentrations in 64 HIV-infected individuals (45 men and 19 women) with evidence of fat redistribution (LIPO) in comparison to 30 HIV-infected individuals (20 men and 10 women) without evidence of fat redistribution (NONLIPO) and 32 HIV-negative healthy control subjects (C) (21 males and 11 females) of similar age and body mass index (BMI). Glucose, insulin, and free fatty acid (FFA) levels were measured in response to a 75-g oral glucose tolerance test (OGTT) in the LIPO, NONLIPO, and C subjects. In addition, fasting lipids were obtained, and body composition was determined by anthropometric measurements and dual-energy x-ray absorptiometry (DXA). Fasting FFA concentrations were significantly increased in the LIPO group as compared with NONLIPO and C subjects (0.74 +/- 0.03 v 0.60 +/- 0.04 [mean +/- SEM] mmol/L, P =.002, LIPO v NONLIPO; 0.74 +/- 0.03 v 0.59 +/- 0.03 mmol/L, P =.001, LIPO v C). In contrast, fasting FFA concentrations were not increased in the NONLIPO group (0.60 +/- 0.04 v 0.59 +/- 0.03, P =.909, NONLIPO v C). Similarly, fasting triglycerides and 120-minute OGTT FFA were significantly increased in the LIPO group as compared with the NONLIPO and C group. FFA decreased in HIV-infected LIPO, NONLIPO, and C subjects in response to OGTT, but the 120-minute FFA concentrations remained significantly elevated in LIPO patients compared with NONLIPO and C subjects. In a multivariate regression model of LIPO patients, fasting FFA (P =.027) was a strong independent predictor of insulin area under the curve (AUC), controlling for age, BMI, gender, and body composition (r(2) for model =.31). No differences were observed in FFA concentrations in the LIPO group in an analysis based on current protease inhibitor (PI) use. These data suggest that FFA concentrations are increased in HIV-infected patients with fat redistribution. Increased fasting concentrations of fatty acids are associated with abnormal insulin responses to standard glucose challenge in HIV-infected patients with fat redistribution. Further studies are necessary to determine the mechanism of increased fatty acid concentrations and the role played by increased FFA in mediating insulin resistance in this population.

Body fat distribution and metabolic derangements in patients with familial partial lipodystrophy associated with mandibuloacral dysplasia

Mandibuloacral dysplasia (MAD) is a rare autosomal recessive disorder that is characterized by mandibular and clavicular hypoplasia, acroosteolysis, delayed closure of cranial sutures, joint contractures, and mottled cutaneous pigmentation. It is also associated with partial lipodystrophy, but the pattern of fat loss has not been well characterized. We studied body fat distribution in two male and two female patients with MAD by anthropometry, dual energy x-ray absorptiometry, and magnetic resonance imaging. Blood glucose and insulin responses during an oral glucose tolerance test and fasting serum lipoproteins were determined. Three of the four subjects had loss of sc fat from the extremities with normal or slight excess in the neck and truncal regions (termed type A pattern). In contrast, one patient had generalized loss of sc fat involving the face, trunk, and extremities (type B pattern). All of the patients had normal glucose tolerance but had fasting and postprandial hyperinsulinemia suggestive of insulin resistance. Elevated serum triglycerides with low high-density lipoprotein cholesterol levels were noted in three subjects. We conclude that familial partial lipodystrophy associated with MAD presents with two types of body fat distribution patterns, both of which are associated with insulin resistance and its metabolic complications.

Management of antiretroviral-related nutritional problems: state of the science

A number of new nutritional problems have been documented in HIV-infected persons treated with antiretroviral therapy, but only a limited amount of data exist on strategies to manage these problems. Initial studies have focused on drug therapy as the sole management strategy. Controlled trials are needed to confirm the benefits of drug therapy and to evaluate the usefulness of preventive measures, lifestyle changes, and complementary and alternative therapies in managing antiretroviral-related nutritional problems.

Familial lipodystrophy associated with neurodegeneration and congenital cataracts

BACKGROUND

The lipodystrophies are characterized by loss of body fat and metabolic disturbances, but the CNS is seldom affected.

METHODS

An investigation of a family with partial lipodystrophy and neurologic abnormalities included lipid analysis, dual-energy x-ray absorbtiometry (DEXA) for adiposity, insulin resistance, karyotype and other genetic analyses, peroxisomal function, glycosylation pattern of transferrin and thyroglobulin, and muscle biopsy.

RESULTS

The propositus, a 28-year-old woman with congenital partial lipodystrophy and cataracts, presented with a spastic-ataxic gait and lower extremity paresthesiae at age 18. Laboratory investigation revealed a type V hyperlipidemia pattern, insulin resistance, and high alpha-tocopherol levels. A similar syndrome in other family members suggested an autosomal dominant pattern of inheritance.

DISCUSSION

The progressive neurologic degenerative condition associated with this autosomal dominant, partial lipodystrophy may be misdiagnosed as MS or spinocerebellar degeneration. Search for a few relevant candidate genes was unrevealing. A genome-wide search to determine the molecular etiology can be undertaken if other similar cases are identified.

Metabolic complications of HIV infection: translating research findings into clinical practice

The editors of ACC recognize that our coverage of the topic of metabolic complications is unable to address all of the issues that clinicians face on a daily basis. The absence of information to guide clinicians on the management of lipoatrophy, fat accumulation, avascular necrosis, and breast enlargement is a reflection of the limitations of current data, not a statement about the importance of these topics. As new data emerge in these areas we will strive to keep our readers informed. Much work remains to be done in defining the causes of, and treatments for, the metabolic complications of HIV infection. For starters, a more critical assessment of the metabolic profiles of each of the available antiretroviral agents--or, at a minimum, an understanding of their impact on lipid levels and glucose metabolism in treatment-naive patients--is long overdue. Although it is clearly not possible to examine all of the potential combinations of the available agents in equal depth, some basic information about all of the FDA-approved drugs should be developed. Only through careful study of the underlying mechanisms by which these agents contribute to the development of the myriad of metabolic abnormalities will we be able to develop new agents and optimal management strategies for people living with HIV infection.

The role of increased liver triglyceride content: a culprit of diabetic hyperglycaemia?

The role of fat in the aetiology of insulin resistance and type 2 diabetes has been re-considered in the present review. This is because of the questions raised by recent created mouse models imitating human lipodystrophy diabetes. It appears that hepatic steatosis, which is shared by both lipodystrophy and most if not all obesity patients, may play a key role in the pathogenesis of insulin resistance and type 2 diabetes despite the fact that lipodystrophy is an extreme state and occurs more rarely than obesity. The possible link between lipid and glucose metabolisms via peroxisome activity has been examined and its role in determining hyperglycaemia is suggested. Moreover, new avenues towards a better understanding of insulin resistance at the genomic level have also been proposed. It appears that one of the most fundamental biological phenomena, fuel selection, may underlie the causes of diabetic hyperglycaemia and perplex the role of fat in the aetiology of insulin resistance.

Becker's naevus of the thigh with lipoatrophy: report of two cases

Although Becker's naevus is most common in males, cases with associated lipoatrophy are more frequently reported in women. Two women are described in whom Becker's naevus of the thigh was associated with localized lipoatrophy. Neither had any bony abnormality or functional deficit.

[Membranous lipodystrophy of the bone]

Membranous lipodystrophy is a rare disease in which cyst-like lesions of fat occur in subcutaneous and other sites including bone marrow, together with sudanophilic leukoencephalopathy. The disease has been reported mostly in Finland and in Japan, with sporadic cases from USA, Belgium, Italy, and France. The cyst-like lesions of limb bones progress in early adult life, usually followed by neurological disorders including convulsions and presenile dementia. Histologically, the fat cells of the bone marrow, synovial membrane, and other sites, are replaced by a convoluted, hyaline, eosinophilic membrane that surrounds a large space. The histochemical and ultrastructural characteristics of the membranes are described. In the brain, atrophy of the subcortical white matter of the frontal and temporal lobes with marked astrocytosis and fibrillary gliosis, and a slight or moderate degeneration of myelin sheaths, are the most prominent changes. Genetic studies of the disease have been reported, revealing an autosomal recessive gene, explaining both its sporadic and familial occurrence, with mutations involving the gene encoding a transmembrane protein, key activating signal transduction element in NK cells (TYROBP). The pathogenesis of membranocystic changes is still unknown: result of a metabolic disorder or circulatory disturbances.