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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.

Adult↗

Lamin expression in human adipose cells in relation to anatomical site and differentiation state.

Familial partial lipodystrophy-Dunnigan variety (FPLD) is an autosomal dominant form of lipodystrophy resulting in a loss of sc fat from the trunk and limbs with retention of fat in the visceral depots, face, and neck. Specific point mutations in the gene encoding the nuclear lamina proteins, lamins A and C, have been established to cause this syndrome. We undertook studies to determine which members of the lamin family were expressed in human fat cells, to examine the effect of differentiation state on lamin A and C expression in human preadipocytes, and to test the hypothesis that regional variation in lamin A/C expression might underlie the stereotyped anatomical pattern of FPLD. Lamins A, C, and B1, but not B2, were expressed in sc mature human adipocytes. Subcutaneous preadipocytes expressed all four lamins, with lamin A and C expression increasing with ex vivo differentiation. Consistent with previously reported resistance to ex vivo differentiation, omental preadipocytes did not show an increase in lamin A or C mRNA under these conditions. Lamin A/C mRNA levels were similar in isolated mature adipocytes and preadipocytes from omental, sc, and neck sites. However, lamin C was consistently lower, and the ratio of lamin A/C mRNA was higher in sc mature adipocytes compared with omental mature adipocytes. We conclude that the depot-specific pattern of lamin A/C expression does not provide clues to the mechanism of FPLD. Nonetheless, these studies provide new information regarding the expression of lamin isoforms in normal human adipose cells, which will inform future studies of the molecular pathogenesis of FPLD.

Adipocytes↗

Lipomatous disorder of the peri-trochanteric soft tissue: case report and review.

Disorders of fatty tissue metabolism and body contour are frequently described in the literature. Several different syndromes have been ascribed to recurring characteristics of fatty deposition with similar underlying etiologies. These syndromes can generally be classified into the lipomatoses (abnormal accumulations of fat) and the lipodystrophies (abnormal fat atrophy). The authors describe a case of isolated symmetrical lipomatosis of the soft tissue overlying the trochanters that developed a recurrence after treatment with liposuction. They have attempted to match this patient's disorder into 1 of several reported syndromes, with benign symmetric lipomatosis and acquired partial lipodystrophy at the top of the differential diagnosis. However, some characteristics of this patient may warrant a separate categorization for her condition. In this case report, the current literature on disorders of fatty tissue metabolism is reviewed and a discussion of relevant factors and issues surrounding their clinical significance and management is provided.

Adult↗

Childhood acquired lipodystrophy: a retrospective study.

OBJECTIVE: We sought to describe the clinical characteristics and complications of children with acquired lipodystrophy (LD). METHODS: We conducted a retrospective chart review at a tertiary, academic children's hospital of children clinically given a diagnosis of acquired LD between January 1997 and December 2004. RESULTS: During the study period, 23 patients were identified. Their mean age at diagnosis was 9.74 +/- 3.98 years. Of patients, 61% were girls. The length of the follow-up was 4.8 +/- 3.5 years from the time of LD diagnosis. Of patients, 30% had evidence of localized disease (7 of 23), 26% (6 of 23) had localized partial disease, and 44% (10 of 23) had generalized LD. The most common underlying diagnosis was dermatomyositis (78%), alone or in association with other autoimmune diseases (juvenile rheumatoid arthritis 17%). Panniculitis with autoimmunity was noted in 17% of the patients. More than half of the patients had at least one complication attributable to LD such as acanthosis nigricans (22%), hyperpigmentation (22%), hepatomegaly (13%), hypertension (13%), protuberant abdomen (9%), and hyperlipidemia (4%). The only predictor for development of complications was the age of diagnosis of LD, with younger age being associated with increased risk (7 vs 12 years, P = .04). LIMITATIONS: Limitations were inherent to the retrospective design. CONCLUSIONS: Childhood acquired LD is seen more frequently in the context of autoimmunity. Affected children should be monitored for the development of complications, particularly if given a diagnosis of LD at a younger age.

Acanthosis Nigricans↗

Human laminopathies: nuclei gone genetically awry.

Few genes have generated as much recent interest as LMNA, LMNB1 and LMNB2, which encode the components of the nuclear lamina. Over 180 mutations in these genes are associated with at least 13 known diseases--the laminopathies. In particular, the study of LMNA, its products and the phenotypes that result from its mutation have provided important insights into subjects ranging from transcriptional regulation, the cell biology of the nuclear lamina and mechanisms of ageing. Recent studies have begun the difficult task of correlating the genotypes of laminopathies with their phenotypes, and potential therapeutic strategies using existing drugs, modified oligonucleotides and RNAi are showing real promise for the treatment of these diseases.

Aging, Premature↗

[Laminopathies--one gene, multiple diseases].

Laminopathies are genetic diseases that encompass a wide spectrum of phenotypes with diverse tissue pathologies and result mainly from mutations in the LMNA gene encoding nuclear lamin A/C. To date, at least 9 different human diseases, which superficially seem to share little with one another, result from LMNA mutations. The position of the mutation within LMNA appears to be associated with the phenotypes. This review gives an overview of genotype-phenotype relationship and describes recent advances in animal models and pathogenic mechanisms.

Animals↗

Familial incidence of C3 nephritic factor, partial lipodystrophy and membranoproliferative glomerulonephritis.

C3 nephritic factor is an IgG autoantibody that causes complement activation by stabilizing the alternative pathway C3 convertase. It is associated with partial lipodystrophy and membrano-proliferative glomerulonephritis. The occurrence of C3 nephritic factor, partial lipodystrophy and membranoproliferative glomerulonephritis, whether singly or in any combination, is usually sporadic. We describe the coexistence of all three of these conditions in members spanning two generations of a single family. This suggests that the pathogenesis of these conditions may be linked and that genetically determined factors may, in some circumstances, contribute to disease susceptibility.

Biopsy↗

Lipodystrophy of the extremities. A dominantly inherited syndrome associated with lipatrophic diabetes.

A female patient with the following symptoms has been observed: complete absence of subcutaneous fat on the arms and legs, well developed adipose tissue on the trunk and face, severe hyperlipidemia, eruptive xanthomas, insulin resistant diabetes mellitus with lack of ketoacidosis, hepatomegaly and elevated basal metabolic rate. The patient thus exhibited all characteristics of lipatrophic diabetes (Lawrence type of diabetes). The mother and a sister of the patient were found to have the same peculiar appearance and a slight hyperlipidemia but no diabetes mellitus. The combination of this type of partial lipodystrophy with severe hyperlipidemia, insulin resistant diabetes mellitus without ketoacidosis and elevated basal metabolic rate was further observed in 2 unrelated patients without known familial occurrence. Thus partial lipodystrophy of the extremities is another, previously undescribed, syndrome associated with the Lawrence type of diabetes mellitus. In the 1 family the syndrome of lipodystrophy and hyperlipidemia is dominantly inherited. Besides the autosomal recessively inherited syndrome of congenital generalized lipodystrophy there is a heterogenous group of dominantly inherited syndromes with various types of lipodystrophy.

Adult↗

Dunnigan-Kobberling syndrome: an autosomal dominant form of partial lipodystrophy.

Dunnigan-Kobberling syndrome is a form of partial lipodystrophy characterized by sparing of the face. Despite descriptions of six families since 1974, details of total body adipose tissue distribution and studies of carbohydrate and fat metabolism are lacking. The mode of inheritance also remains unclear, with most authors favouring an X-linked dominant transmission lethal in the hemizygous male. We examined 23 members of a family, of whom at least eight had partial lipodystrophy. Auxological evaluation and cross-sectional imaging showed absence of subcutaneous fat, presence of adipose tissue inside the body cavities, and skeletal muscle hypertrophy. Biochemical evaluation identified insulin resistance but revealed inadequate suppression of non-esterified fatty acids. In this family, male-to-male transmission supports an autosomal dominant mode of inheritance for Dunnigan-Kobberling syndrome.

Acanthosis Nigricans↗

[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.

Adipose Tissue↗

Partial lipodystrophy and renal disease.

Partial lipodystrophy is a rare disorder with both autosomal recessive and familial forms. The cutaneous findings, which are often subtle, consist of a gradual loss of subcutaneous fat from the face and upper body. Low levels of C3, occasionally low C5 and the presence of the nephritic factor help to identify these patients. Associated systemic abnormalities include the development of mesangiocapillary glomerulonephritis and an increased incidence of autoimmune diseases. Recognition of this unusual disorder is essential for diagnosis and treatment of underlying potentially life- threatening disease.

Adult↗

Autosomal dominant partial lipodystrophy associated with Rieger anomaly, short stature, and insulinopenic diabetes.

We describe the clinical findings and natural history of an autosomal dominant form of partial lipodystrophy found in four affected individuals from three generations in the same family. The lipodystrophy was present from infancy/early childhood, involved primarily the face and local areas on the buttocks, and was nonprogressive. Affected individuals also had the Rieger anomaly, midface hypoplasia, short stature, retarded bone age, and hypotrichosis. An affected woman developed insulinopenic diabetes mellitus at 39 yr and another had glucose intolerance at 55 yr.

Adult↗

Association between nuclear lamin A/C R482Q mutation and partial lipodystrophy with hyperinsulinemia, dyslipidemia, hypertension, and diabetes.

Nuclear lamins A and C are encoded by LMNA and are present in terminally differentiated cells. Lamins participate in DNA replication, chromatin organization, arrangement of nuclear pores, nuclear growth, and anchorage of nuclear membranes. In several Canadian probands with partial lipodystrophy, since found to have a common ancestor, we identified a rare novel LMNA mutation, R482Q, that completely cosegregated with the partial lipodystrophy phenotype. We evaluated the relationship between quantitative metabolic phenotypes in both diabetic and nondiabetic carriers of LMNA R482Q and family controls, who were LMNA R482/R482 homozygotes. We found that when compared with LMNA R482/R482 homozygotes: (1) diabetic LMNA Q482/R482 heterozygotes had significantly higher glucose, glycosylated hemoglobin, triglycerides, insulin and C-peptide, and significantly lower HDL cholesterol; and (2) nondiabetic LMNA Q482/R482 heterozygotes had significantly higher triglycerides, insulin and C-peptide, and significantly lower HDL cholesterol. We also found that diabetic LMNA Q482/R482 heterozygotes were older and more likely to take antihypertensive medications. Thus, LMNA R482Q was associated with lipodystrophy, hyperinsulinemia, dyslipidemia, diabetes, and hypertension. The results indicate that perturbations in plasma lipids precede the plasma glucose abnormalities in LMNA Q482-associated hyperinsulinemia. Thus, rare mutations in a nuclear structural protein can be associated with markedly abnormal qualitative and quantitative metabolic phenotypes

Adolescent↗

Bi-allelic loss-of-function variants in POC5 cause a syndromic retinal, endocrine, and neuromuscular ciliopathy.

PURPOSE: A homozygous loss-of-function (LoF) variant in POC5 was previously described in an individual with retinitis pigmentosa. We identified POC5 variants in 12 probands with a syndromic phenotype. We aim to define the phenotype spectrum and molecular mechanism associated with biallelic POC5 LoF variants. METHODS: We studied a cohort of 12 families with bi-allelic LoF POC5 variants and performed detailed phenotype analysis. POC5 localization studies were performed in 3 proband-derived fibroblast cell lines. RESULTS: Detailed phenotyping of probands with POC5 variants expands the phenotype spectrum beyond ocular manifestations. This syndrome causes not only rod-cone dystrophy but also diabetes mellitus with severe insulin resistance and partial lipodystrophy, kidney disease, and muscle cramps. The POC5 protein plays an essential role during cell cycle and cilium formation. Interestingly, POC5 localization studies in 3 proband-derived fibroblast cell lines show aberrant localization suggesting a ciliary defect. The phenotypes of the 12 families in this study fit well within the ciliopathy phenotype spectrum, except for lipodystrophy, which is not common in ciliopathies. CONCLUSION: We describe a multiorgan syndrome caused by bi-allelic LoF variants in POC5. This underscores the pleiotropic effects of POC5 variants and highlights the significance of adipose tissue and metabolic dysfunction in ciliopathies.

Humans↗

Peroxisome proliferator-activated receptor-gamma and insulin action: insights from human genetics.

Peroxisome proliferator-activated receptor-gamma (PPARgamma), an orphan nuclear receptor, mediates adipocyte differentiation and is the cellular target for the thiazolidinedione group of insulin-sensitizing antidiabetic agents. We screened this receptor gene in a cohort of subjects with severe insulin resistance and have identified heterozygous missense mutations in several individuals from three families. Functional studies indicate that the receptor mutants are transcriptionally impaired and inhibit wild type PPARgamma action in a dominant-negative manner. The clinical phenotype of patients includes partial lipodystrophy, early-onset hypertension, dyslipidaemia and hepatic steatosis. Factors which contribute to the severe insulin resistance in affected individuals include diminished body fat mass, impaired lipid flux in adipose tissue and reduced circulating levels of adiponectin. In a large kindred of five individuals with severe insulin resistance, we have identified frameshift/premature stop mutations in PPARGAMMA; and the muscle-specific regulatory subunit of protein phosphatase 1 (PPP1R3A). The frameshift PPARgamma mutant exhibits complete loss of function with no dominant-negative activity; the PPP1R3A truncation mutant is mislocalized intracellularly. Individuals harbouring either gene defect alone have normal circulating insulin levels, but a combination of both genetic abnormalities co-segregates with severe insulin resistance.

Cohort Studies↗

Human metabolic syndrome resulting from dominant-negative mutations in the nuclear receptor peroxisome proliferator-activated receptor-gamma.

We previously reported a syndrome of severe hyperinsulinemia and early-onset hypertension in three patients with dominant-negative mutations in the nuclear hormone receptor peroxisome proliferator-activated receptor (PPAR)-gamma. We now report the results of further detailed pathophysiological evaluation of these subjects, the identification of affected prepubertal children within one of the original families, and the effects of thiazolidinedione therapy in two subjects. These studies 1) definitively demonstrate the presence of severe peripheral and hepatic insulin resistance in the affected subjects; 2) describe a stereotyped pattern of partial lipodystrophy associated with all the features of the metabolic syndrome and nonalcoholic steatohepatitis; 3) document abnormalities in the in vivo function of remaining adipose tissue, including the inability of subcutaneous abdominal adipose tissue to trap and store free fatty acids postprandially and the presence of very low circulating levels of adiponectin; 4) document the presence of severe hyperinsulinemia in prepubertal carriers of the proline-467-leucine (P467L) PPAR-gamma mutation; 5) provide the first direct evidence of cellular resistance to PPAR-gamma agonists in mononuclear cells derived from the patients; and 6) report on the metabolic response to thiazolidinedione therapy in two affected subjects. Although the condition is rare, the study of humans with dominant-negative mutations in PPAR-gamma can provide important insight into the roles of this nuclear receptor in human metabolism.

Abdomen↗