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Congenital Generalized Lipodystrophy Type 1

GCL

Congenital generalized lipodystrophy type 1 (CGL1) is a rare metabolic disorder inherited in an autosomal recessive pattern. It has been related to mutations of the AGPAT2 gene. Affected individuals are greatly lacking body fat, but preserve mechanical adipose tissue. Despite recent advances in CGL1 therapy - recombinant analogs of human leptin have been proven highly effective to control metabolic complications of the disease - life quality and expectancy of CGL1 patients remain decreased.


Presentation

The near-total absence of body fat is characteristic of congenital generalized lipodystrophies and is usually apparent at birth. Less frequently, it is recognized in the neonatal period, in infancy or in childhood, as has been shown in a recently published study: The mean age of patients at the onset of fat loss has been reported to be 0.3 months, with a range of from birth to 12 years [1]. At the same time, extreme muscularity is observed. Veins of arms and legs are rather prominent since they are not hidden by subcutaneous fat. Body composition and fat distribution pattern may raise suspicion as to the molecular type of lipodystrophy [2]: CGL1 patients are usually lacking subcutaneous, intrathoracic and intraabdominal fat, while mechanical adipose tissue is present. These patients' palms and soles dispose of normal subcutaneous fat [3]. Considerable amounts of adipose tissue are also recognized within the orbita, periarticularly, in the renal sinus, and in the pubic and perineal areas. With regards to the patients' general appearance, acromegaly-like large jaws, hands, and feet may be noted [4].

Hepatomegaly and splenomegaly may be found during the postnatal examination and may provoke umbilical prominence or even umbilical hernia [5]. In some patients, hepatosplenomegaly only develops during childhood. Initially, hepatic enlargement is due to the accumulation of fat in this organ, but liver disease may progress from hepatic steatosis to liver fibrosis, liver cirrhosis and liver failure.

Furthermore, acanthosis nigricans is typical of CGL1 and other types of congenital generalized lipodystrophy, but is not necessarily present before puberty. Predilection sites for this pigmentary anomaly are the neck, axillae and groin. Other skin areas may be affected, though. Acanthosis nigricans is considered an early indicator of insulin resistance and is usually detected years before diabetes mellitus becomes symptomatic [6]. Indeed, CGL1-associated diabetes mellitus doesn't generally cause asthenia, weight loss, polyuria, or polydipsia until the second decade of life.

By the time CGL1 patients reach puberty, additional symptoms may manifest in females. Breast development is undisturbed with regards to glandular tissue, but subcutaneous fat is largely missing. Affected women often complain about irregular menstruation, but may also suffer from primary or secondary amenorrhea and polycystic ovary syndrome. Mild hirsutism and clitoromegaly may also be associated with the disease. Most female patients are unable to conceive while males are usually fertile.

Severe hypoleptinemia may induce an increase in appetite. In those patients suffering from hypertriglyceridemia, eruptive xanthomas can frequently been observed. This condition also predisposes for recurrent pancreatitis, particularly in case of poorly controlled diabetes mellitus.

Physician
  • ISBN 978-0-7216-2921-6 . a b "Lipodystrophy Disorders – Inherited Lipodystrophies – NORD Physician Guides – Rare Disease Resources for Medical Professionals" . NORD Physician Guides – Rare Disease Resources for Medical Professionals .[en.wikipedia.org]
  • Look at other dictionaries: Berardinelli-Seip syndrome — Be·rar·di·nel·li Seip syndrome (bə rahr″dĭ nelґe sīpґ) [Waldemar Berardinelli, Argentine physician, 1903â “1956; Martin Fredrik Seip, Norwegian pediatrician, born 1921] total lipodystrophy … Medical[medicine.academic.ru]
Tall Stature
  • The most common clinical manifestations of Berardinelli syndrome are acanthosis nigricans, steatosis with hepatomegaly, and tall stature. Acromegaloid features, cardiomyopathy, hypertension, and developmental disability may also occur.[scirp.org]
Splenomegaly
  • Hepatomegaly and splenomegaly may be found during the postnatal examination and may provoke umbilical prominence or even umbilical hernia. In some patients, hepatosplenomegaly only develops during childhood.[symptoma.com]
  • […] throughout the body – mainly in the neck, trunk, and groin. [3] The disorder also has characteristic features like hepatomegaly or an enlarged liver which arises from fatty liver and may lead to cirrhosis , muscle hypertrophy , lack of adipose tissue , splenomegaly[en.wikipedia.org]
Polydipsia
  • Indeed, CGL1-associated diabetes mellitus doesn't generally cause asthenia, weight loss, polyuria, or polydipsia until the second decade of life. By the time CGL1 patients reach puberty, additional symptoms may manifest in females.[symptoma.com]
  • Diabetes mellitus: Can be difficult to control; Manifests by weight loss, polydipsia, polyuria, or asthenia and is frequently the presenting finding in the second decade; Presents on occasion in early adulthood.[ncbi.nlm.nih.gov]
Heart Disease
  • Diabetes mellitus, heart disease, and hepatopathy are frequent complications of CGL1 and decrease the life expectancy of affected individuals.[symptoma.com]
Liver Fibrosis
  • Initially, hepatic enlargement is due to the accumulation of fat in this organ, but liver disease may progress from hepatic steatosis to liver fibrosis, liver cirrhosis and liver failure.[symptoma.com]
Hepatosplenomegaly
  • In some patients, hepatosplenomegaly only develops during childhood.[symptoma.com]
Hirsutism
  • Mild hirsutism and clitoromegaly may also be associated with the disease. Most female patients are unable to conceive while males are usually fertile. Severe hypoleptinemia may induce an increase in appetite.[symptoma.com]
  • Some women display hyperandrogyny, clinically manifested by severe hirsutism and alterations in the menstrual cycle such as oligomenorrhea.[scirp.org]
  • […] body – mainly in the neck, trunk, and groin. [3] The disorder also has characteristic features like hepatomegaly or an enlarged liver which arises from fatty liver and may lead to cirrhosis , muscle hypertrophy , lack of adipose tissue , splenomegaly , hirsutism[en.wikipedia.org]
  • Hirsutism manifests with low frontal and posterior hairline; hypertrichosis is apparently independent of hormonal stimulation. Precocious puberty in females.[ncbi.nlm.nih.gov]
Eruptions
  • Acanthosis nigricans and eruptive xanthomas may result from CGL1, but also irregular menstruation, amenorrhea, polycystic ovary syndrome and pancreatitis.[symptoma.com]
  • Original Investigations 71 Downloads 38 Citations Summary 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[link.springer.com]
Absence of Subcutaneous Fat
  • […] of subcutaneous fat . [8] CGL3 patients have serum creatine kinase concentrations much higher than normal (2.5 to 10 times the normal limit).[en.wikipedia.org]
  • Original Investigations 71 Downloads 38 Citations Summary 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[link.springer.com]
Advanced Bone Age
  • Acromegaloid features include gigantism, muscular hypertrophy, advanced bone age, prognathism, prominent orbital ridges, enlarged hands and feet, clitoromegaly, and enlarged external genitalia in males. Hepatomegaly.[ncbi.nlm.nih.gov]
Asthenia
  • Indeed, CGL1-associated diabetes mellitus doesn't generally cause asthenia, weight loss, polyuria, or polydipsia until the second decade of life. By the time CGL1 patients reach puberty, additional symptoms may manifest in females.[symptoma.com]
  • Diabetes mellitus: Can be difficult to control; Manifests by weight loss, polydipsia, polyuria, or asthenia and is frequently the presenting finding in the second decade; Presents on occasion in early adulthood.[ncbi.nlm.nih.gov]
Neonate-Onset
  • Garg A , Kircher M , Del Campo M , Amato RS , Agarwal AK : Whole exome sequencing identifies de novo heterozygous CAV1 mutations associated with a novel neonatal onset lipodystrophy syndrome . Am J Med Genet A 2015; 167A : 1796–1806. 10.[nature.com]
Secondary Amenorrhea
  • Affected women often complain about irregular menstruation, but may also suffer from primary or secondary amenorrhea and polycystic ovary syndrome. Mild hirsutism and clitoromegaly may also be associated with the disease.[symptoma.com]

Workup

Congenital generalized lipodystrophies are hereditary disorders and thus, it should be determined whether family members have suffered from symptoms similar to those observed in the patient at hand [7]. Also, consanguinity of the parents considerably increases the likelihood of diseases inherited in an autosomal recessive fashion, as is the case with CGL1.

A comprehensive metabolic panel should be obtained in order to detect characteristic anomalies even in the absence of the respective clinical symptoms [8]. The triad of insulin resistance with or without overt diabetes mellitus, hypertriglyceridemia and hepatic steatosis - associated with abnormal liver function tests - is considered to be characteristic of, yet no specific for congenital generalized lipodystrophies [4] [6]. In detail, biochemical analyses typically yield the following results [9]:

Diagnostic imaging may provide valuable hints on the molecular type of congenital generalized lipodystrophy. Whole-body magnetic resonance imaging allows for the assessment of body fat distribution. In CGL1 patients, a distribution pattern as described in the previous paragraph is to be expected. Sonography is the technique of choice to assess the overall size of the liver and the progress of fibrotic remodeling in follow-ups. Furthermore, radiography and computer tomography may reveal the presence of lytic lesions along the long bones, a condition that predisposes for pathological fractures [7]. The inability to replace hematopoietic marrow by bone marrow fat may be the cause of those lesions. Lytic lesions of the skeleton are mainly seen in CGL1 and rarely occur in other types of congenital generalized lipodystrophy.

Genetic analyses have to be conducted to identify the causal mutation of the AGPAT2 gene.

Hepatocellular Carcinoma
  • CGL1 patients are at particularly high risks of cardiovascular accidents, liver cirrhosis, and hepatocellular carcinoma.[symptoma.com]

Treatment

There is no causal therapy for CGL1. Metabolic complications that arise due to the genetic disorder have to be treated symptomatically, by putting into practice dietary measures and by means of pharmacotherapy:

  • In general, patients suffering from congenital generalized lipodystrophy are recommended to avoid excessive food intake and restrict the ingestion of fat and carbohydrates. Due to the lack of adipose tissue, energy storage is limited and fluctuations in energy supply are poorly compensated.
  • Before recombinant analogs of human leptin have been used to treat generalized lipodystrophies, conventional antidiabetics and lipid-lowering drugs had been the mainstay of therapy [10]. However, adequate control of metabolic anomalies has rarely been achieved. By contrast, leptin analogs significantly improve insulin resistance and diabetes mellitus as well as hypertriglyceridemia and related complications.
  • Still, many patients require additional medication, either because they never respond satisfactorily to leptin analogs or because the efficacy of that therapy decreases due to the formation of antibodies against the recombinant hormone [11]. With regards to mitigating insulin resistance and hyperglycemia, thiazolidinediones such as pioglitazone and troglitazone have been shown to be more effective than metformin. However, in severe cases, glycemic control can only be achieved by high doses of insulin [2].

Additionally, fillers like poly-L lactic acid and calcium hydroxyapatite may be used to conceal the lack of subcutaneous fat in cosmetically sensitive areas [8].

Prognosis

Diabetes mellitus, heart disease, and hepatopathy are frequent complications of CGL1 and decrease the life expectancy of affected individuals [8]. CGL1 patients are at particularly high risks of cardiovascular accidents, liver cirrhosis, and hepatocellular carcinoma [6]. According to a meta-analysis published recently, the mean age at mortality was 12.5 years for patients suffering from any congenital generalized lipodystrophy [1].

Etiology

CGL1 is caused by mutations of the AGPAT2 gene. Both null and missense mutations of the AGPAT2 gene have been described in CGL1 patients, but although compound heterozygosity may be related to minor residual enzyme activity, the type of mutation doesn't seem to correlate with disease severity.

The AGPAT2 gene encodes for member 2 of the 1-acylglycerol-3-phosphate O-acyltransferase family, an enzyme required for the conversion of lysophosphatidic acid to phosphatidic acid. This reaction needs to be catalyzed as part of the triglyceride and phospholipid biosynthesis. AGPAT2 expression is highest in adipose tissue and thus, CGL1 is mainly a lipodystrophic disease.

Epidemiology

To date, about 500 cases of congenital generalized lipodystrophy have been described. The overall prevalence of those diseases comprised in this group has been roughly estimated to 1 in 10,000,000 inhabitants [2], but it may be even lower [5]. Reliable data regarding incidence and prevalence of single types of congenital generalized lipodystrophy cannot be provided, though.

Most cases have been reported in families of African ancestry, in Lebanon, Brazil, and Scandinavia. Consistent with the fact that CGL1 and other types of congenital generalized lipodystrophy are inherited in an autosomal recessive pattern, consanguineous marriage and low genetic variability considerably increase the risk of homozygosity in offspring [2].

Sex distribution
Age distribution

Pathophysiology

Individuals suffering from congenital generalized lipodystrophy lack functional adipocytes. Consequently, lipids are stored in other tissues, namely in muscles and liver, and in fact, patients may present with skeletal muscle hypertrophy and hepatomegaly at birth [8] [12]. Nevertheless, the mean percentage of body fat remains below 10% [1] [10]. In other studies, mean values of less than 6% have been reported [9]. Furthermore, CGL1 is not only associated with abnormal lipid storage but also with considerable metabolic disturbances. This can be explained by the fact that adipose tissue plays an important role in endocrine processes and secretes a variety of hormones. One of those hormones is leptin, a proinflammatory adipokine and regulator of appetite and energy expenditure [8]. Unsurprisingly though, metabolic complications start to arise soon after birth in those affected by congenital generalized lipodystrophy:

  • Insulin resistance and hyperinsulinemia may be detected in affected infants and children, while diabetes mellitus rarely manifests before puberty. CGL1 patients suffer from ketosis-resistant diabetes mellitus [4]. Furthermore, about three out of four patients affected by CGL1 develop hypertriglyceridemia during late childhood or adolescence. It has been speculated that enhanced lipolysis and defective energy storage contribute to the development of this type of dyslipidemia, but further research is necessary to understand how these processes are related to each other [6].
  • Insulin resistance has also been related to hyperandrogenism [10] and hyperandrogenism interferes with ovary function in women suffering from congenital generalized lipodystrophy [2]. Additionally, irregular luteinizing hormone
    stimulation presumably contributes to anovulation and infertility in affected females [2].

Prevention

Affected families may benefit from genetic counseling. Those with a positive family history of hereditary diseases should be informed about the risks inherent in consanguineous marriage, and in case CGL1 has been diagnosed in family members, genetic analyses may help to assess the precise risk for any couple to engender a child homozygous for AGPAT2 mutations.

Summary

The term congenital generalized lipodystrophy refers to a heterogeneous group of disorders, all of which are inherited in an autosomal recessive manner. In general, individuals suffering from congenital generalized lipodystrophy lack adipose tissue from birth and are prone to metabolic disease. Most patients develop severe insulin resistance and diabetes mellitus, hypertriglyceridemia, hepatic steatosis, polycystic ovary syndrome, acanthosis nigricans and
hypertension [2]. There are four types of congenital generalized lipodystrophy, which differ with regards to their etiology, but largely coincide clinically:

Alternative denominations of CGL1 include Berardinelli-Seip syndrome, Berardinelli-Seip congenital lipodystrophy type 1, and AGPAT2-related Brunzell syndrome.

Patient Information

Congenital generalized lipodystrophy type 1 (CGL1) is an inherited disease associated with anomalies of fat storage and metabolism affecting the whole body. In detail, children who inherit defective allels of a gene named AGPAT2 from both their parents will suffer from CGL1. A near-total absence of body fat and extreme muscularity are characteristic of the disease and usually apparent at birth. Furthermore, affected individuals may show umbilical prominence or even have umbilical hernia due to an enlarged liver. These observations can be explained by the fact that functional adipose tissue can only be formed by those disposing of at least one "healthy" AGPAT2 gene. In CGL1 patients, however, adipose tissue is largely missing and lipids are stored in muscles and liver.

Because adipose tissue plays an important role in endocrine processes and secretes a variety of hormones, CGL1 predisposes for metabolic complications such as insulin resistance, hyperinsulinemia, and diabetes mellitus as well as hypertriglyceridemia. In turn, these conditions render CGL1 patients prone to cardiovascular disease and interfere with fertility. Acanthosis nigricans and eruptive xanthomas may result from CGL1, but also irregular menstruation, amenorrhea, polycystic ovary syndrome and pancreatitis.

In order to decrease the risk of such potentially life-threatening complications, metabolic anomalies as described above have to be corrected. Recombinant analogs of human leptin, i.e., of one of those hormones secreted by normal adipose tissue, as well as antidiabetic and lipid-lowering drugs are applied to this end. In some cases, patients require high doses of insulin to sufficiently lower blood glucose concentrations. Still, treatment shouldn't rely on medication alone and needs to be complemented by an appropriate diet. Those suffering from CGL1 are recommended to restrict fat and carbohydrate intake in order to maintain blood lipid levels within desirable ranges and to avoid complications due to fluctuations in energy supply that cannot be compensated.

References

Article

  1. Gupta N, Asi N, Farah W, et al. Clinical Features and Management of Non-HIV-Related Lipodystrophy in Children: A Systematic Review. J Clin Endocrinol Metab. 2017; 102(2):363-374.
  2. Patni N, Garg A. Congenital generalized lipodystrophies--new insights into metabolic dysfunction. Nat Rev Endocrinol. 2015; 11(9):522-534.
  3. Haghighi A, Kavehmanesh Z, Haghighi A, et al. Congenital generalized lipodystrophy: identification of novel variants and expansion of clinical spectrum. Clin Genet. 2015.
  4. Hussain I, Garg A. Lipodystrophy Syndromes. Endocrinol Metab Clin North Am. 2016; 45(4):783-797.
  5. Garg A. Lipodystrophies. Am J Med. 2000; 108(2):143-152.
  6. Prieur X, Le May C, Magré J, Cariou B. Congenital lipodystrophies and dyslipidemias. Curr Atheroscler Rep. 2014; 16(9):437.
  7. Miranda DM, Wajchenberg BL, Calsolari MR, et al. Novel mutations of the BSCL2 and AGPAT2 genes in 10 families with Berardinelli-Seip congenital generalized lipodystrophy syndrome. Clin Endocrinol (Oxf). 2009; 71(4):512-517.
  8. Quinn K, Purcell SM. Lipodystrophies. StatPearls. Treasure Island (FL): StatPearls Publishing LLC; 2017.
  9. Lima JG, Nobrega LH, de Lima NN, do Nascimento Santos MG, Baracho MF, Jeronimo SM. Clinical and laboratory data of a large series of patients with congenital generalized lipodystrophy. Diabetol Metab Syndr. 2016; 8:23.
  10. Diker-Cohen T, Cochran E, Gorden P, Brown RJ. Partial and generalized lipodystrophy: comparison of baseline characteristics and response to metreleptin. J Clin Endocrinol Metab. 2015; 100(5):1802-1810.
  11. Beltrand J, Lahlou N, Le Charpentier T, et al. Resistance to leptin-replacement therapy in Berardinelli-Seip congenital lipodystrophy: an immunological origin. Eur J Endocrinol. 2010; 162(6):1083-1091.
  12. Van Maldergem L. Berardinelli-Seip Congenital Lipodystrophy. In: Adam MP, Ardinger HH, Pagon RA, et al., eds. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2017.

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Last updated: 2019-07-11 19:56