Diabetes mellitus with Laron syndrome: case report

The role of acid-labile subunit (ALS) in the modulation of GH-IGF-I action

Acid-labile subunit (ALS) deficiency (ACLSD) constitutes the first monogenic defect involving a member of the Insulin-like Growth Factor (IGF) binding protein system. The lack of ALS completely disrupts the circulating IGF system. Autocrine/paracrine action of local produced IGF-I could explain the mild effect on growth. In the present work we have revised the more relevant clinical and biochemical consequences of complete ACLSD in 61 reported subjects from 31 families. Low birth weight and/or length, reduced head circumference, height between -2 and -3 SD, pubertal delay and insulin resistance are commonly observed. Partial ACLSD could be present in children initially labeled as idiopathic short stature, presenting low IGF-I levels, suggesting that one functional IGFALS allele is insufficient to stabilize ternary complexes. Dysfunction of the GH-IGF axis observed in ACLSD may eventually result in increased risk for type-2 diabetes and tumor progression. Consequently, long term surveillance is recommended in these patients.

Mexican case report of a never-treated Laron syndrome patient evolving to metabolic syndrome, type 2 diabetes, and stroke

Glucose and lipid profile together with blood pressure should always be considered for low sera‐IGF‐1 patients. Even when adulthood is reached, IGF‐1 therapy in these patients should be pursued as metabolic and protective cellular effects could be triggered. Real incidence of growth hormone insensitivity is still to be uncovered.

Growth Hormone's Effect on Adipose Tissue: Quality versus Quantity

Obesity is an excessive accumulation or expansion of adipose tissue (AT) due to an increase in either the size and/or number of its characteristic cell type, the adipocyte. As one of the most significant public health problems of our time, obesity and its associated metabolic complications have demanded that attention be given to finding effective therapeutic options aimed at reducing adiposity or the metabolic dysfunction associated with its accumulation. Growth hormone (GH) has therapeutic potential due to its potent lipolytic effect and resultant ability to reduce AT mass while preserving lean body mass. However, AT and its resident adipocytes are significantly more dynamic and elaborate than once thought and require one not to use the reduction in absolute mass as a readout of efficacy alone. Paradoxically, therapies that reduce GH action may ultimately prove to be healthier, in part because GH also possesses potent anti-insulin activities along with concerns that GH may promote the growth of certain cancers. This review will briefly summarize some of the newer complexities of AT relevant to GH action and describe the current understanding of how GH influences this tissue using data from both humans and mice. We will conclude by considering the therapeutic use of GH or GH antagonists in obesity, as well as important gaps in knowledge regarding GH and AT.

Impact of Growth Hormone on Regulation of Adipose Tissue

Increasing prevalence of obesity and obesity-related conditions worldwide has necessitated a more thorough understanding of adipose tissue (AT) and expanded the scope of research in this field. AT is now understood to be far more complex and dynamic than previously thought, which has also fueled research to reevaluate how hormones, such as growth hormone (GH), alter the tissue. In this review, we will introduce properties of AT important for understanding how GH alters the tissue, such as anatomical location of depots and adipokine output. We will provide an overview of GH structure and function and define several human conditions and cognate mouse lines with extremes in GH action that have helped shape our understanding of GH and AT. A detailed discussion of the GH/AT relationship will be included that addresses adipokine production, immune cell populations, lipid metabolism, senescence, differentiation, and fibrosis, as well as brown AT and beiging of white AT. A brief overview of how GH levels are altered in an obese state, and the efficacy of GH as a therapeutic option to manage obesity will be given. As we will reveal, the effects of GH on AT are numerous, dynamic and depot-dependent. © 2017 American Physiological Society. Compr Physiol 7:819-840, 2017.

Insulin-like growth factor-1 deficiency and metabolic syndrome

Consistent evidence associates IGF-1 deficiency and metabolic syndrome. In this review, we will focus on the metabolic effects of IGF-1, the concept of metabolic syndrome and its clinical manifestations (impaired lipid profile, insulin resistance, increased glucose levels, obesity, and cardiovascular disease), discussing whether IGF-1 replacement therapy could be a beneficial strategy for these patients. The search plan was made in Medline for Pubmed with the following mesh terms: IGF-1 and "metabolism, carbohydrate, lipids, proteins, amino acids, metabolic syndrome, cardiovascular disease, diabetes" between the years 1963-2015. The search includes animal and human protocols. In this review we discuss the relevant actions of IGF-1 on metabolism and the implication of IGF-1 deficiency in the establishment of metabolic syndrome. Multiple studies (in vitro and in vivo) demonstrate the association between IGF-1 deficit and deregulated lipid metabolism, cardiovascular disease, diabetes, and an altered metabolic profile of diabetic patients. Based on the available data we propose IGF-1 as a key hormone in the pathophysiology of metabolic syndrome; due to its implications in the metabolism of carbohydrates and lipids. Previous data demonstrates how IGF-1 can be an effective option in the treatment of this worldwide increasing condition. It has to distinguished that the replacement therapy should be only undertaken to restore the physiological levels, never to exceed physiological ranges.

Use of continuous glucose monitoring to identify glucose dysregulation in growth hormone insensitivity syndrome

BACKGROUND/AIMS

Monogenic forms of growth hormone insensitivity (GHI) and its treatment with recombinant insulin-like growth factor-1 (rIGF-1) are both associated with glucose dysregulation. We used the information provided by continuous glucose monitoring systems (CGMS) for the clinical management of two children with monogenic GHI prior to the commencement of therapy as well as during the years when they received rIGF-1 treatment and continued to do so after the cessation of therapy.

METHODS

We evaluated the extent of hyper- and hypoglycaemia with CGMS.

RESULTS

In one patient, before treatment CGMS identified self-limiting nocturnal hypoglycaemia. Initiation of rIGF-1 treatment resulted in severe and persistent hypoglycaemia with an absence of spontaneous recovery. Corrective dietary measures were instituted. In a second patient, who had a poor growth response to rIGF-1 therapy, CGMS identified significant fluctuations in daytime glucose levels whilst on treatment with evidence of postprandial hyperglycaemia and both rebound and nocturnal hypoglycaemia. Given the lack of improved growth and the documented glucose dysregulation, treatment was stopped and repeat measurements with CGMS 1 month afterwards showed complete resolution.

CONCLUSIONS

We have demonstrated that CGMS is an effective tool to assess glucose dysregulation in patients with GHI and alters clinical management.

LESSONS FROM 50 YEARS OF STUDY OF LARON SYNDROME

OBJECTIVE

To describe the characteristics of untreated and recombinant insulin-like growth factor 1 (IGF-1)- treated patients with the Laron syndrome (LS) as seen in our clinic over a period of over 50 years. In 1966, we reported a new disease, characterized by dwarfism (-4 to -10 height standard deviation score) typical facial features, small head circumference, obesity, and small genitalia. They resembled congenital growth hormone (GH) deficiency but had high levels of serum human GH and low IGF-1. Since then, our cohort grew to 69 patients, consisting of Jews of oriental origin, Muslins, and Christians originating from the Middle East or Mediterranean area. Many belong to consanguineous families.

METHODS

Molecular genetic investigations revealed that these patients had deletions or mutations in the GH receptor gene, but only individuals homozygous for this defect express the disease, coined "Laron syndrome" (LS; Online Mendelian Inheritance in Man# 262500).

RESULTS

During childhood, LS patients grow slowly, have a retarded bone age and sexual development, but reach full sexual development. The treatment of LS is recombinant IGF-1, which stimulates the linear growth but increases the degree of obesity. Adult-age patients with congenital IGF-1 deficiency are protected from cancer but can develop insulin resistance, glucose intolerance, diabetes, and cardiovascular disease. Due to pathologic changes in the brain related to the type of molecular defect in the GH receptor, they vary in their intellectual capacity. A number of LS patients marry, and with help of pregestational genetic diagnosis, have healthy children.

CONCLUSION

LS is a unique disease model presenting a dissociation between GH and IGF-1 activity.