Evaluation of insulin resistant diabetes mellitus in Alström syndrome: a long-term prospective follow-up of three siblings

Alstrom syndrome with classical findings: a rare case report of monogenic ciliopathy co-occurrence in twins

Introduction and importance

Alstrom syndrome is one of the rarest monogenic ciliopathy belonging to autosomal recessive disorder. The pathophysiology of Alstrom syndrome is not well understood but based upon the available medical literature its mechanism can be linked with recessive mutation in Alstrom syndrome 1(ALSM1) gene resulting in various multiple organ involvement and poor prognosis. Moreover the co-occurrence of such syndrome simultaneously in twins in same period of time is considered rare.

Case presentation

Monochorionic diamniotic twins male born to healthy parents with significant antenatal and natal history along with decreased vision in both eyes in both twins since neonatal period. Throughout the childhood the disease progressed without any confirmatory diagnosis during which the twins underwent simultaneous multiple systemic involvement such as legal blindness in both twins at the age of 11 years, insulin resistance and features of diabetes mellitus, sensorineural hearing loss, subclinical hypothyroidism and various deranged metabolic panels. Certain diagnosis of Alstrom syndrome was made at the age of 16 years in both twins after whole-exome sequencing.

Clinical discussion

Based on genetic profile alstrom syndrome is a unique diagnosis. Along with its multi-organ involvement features, its progression and prognosis should also be looked upon while diagnosis and management in such syndromic patients. The diagnostic delay in such cases is also a matter of concern which can result in further delay in halting adverse effects of the disease itself. The multidisciplinary approach with involvement of endocrionologist, ophthalmologist and audiologist can bring upon improvement in quality of life of the patients.

Conclusion

With the prevalence of 1 in million cases Alstrom Hallgren syndrome is one of the rare genetic disorder with poor prognosis. In our case we present classical findings in twins who were diagnosed as Alstrom syndrome concurrently and further diseases progressed simultaneously.

Body Fat Distribution Contributes to Defining the Relationship between Insulin Resistance and Obesity in Human Diseases

The risk for metabolic and cardiovascular complications of obesity is defined by body fat distribution rather than global adiposity. Unlike subcutaneous fat, visceral fat (including hepatic steatosis) reflects insulin resistance and predicts type 2 diabetes and cardiovascular disease. In humans, available evidence indicates that the ability to store triglycerides in the subcutaneous adipose tissue reflects enhanced insulin sensitivity. Prospective studies document an association between larger subcutaneous fat mass at baseline and reduced incidence of impaired glucose tolerance. Case-control studies reveal an association between genetic predisposition to insulin resistance and a lower amount of subcutaneous adipose tissue. Human peroxisome proliferator-activated receptorgamma (PPAR-γ) promotes subcutaneous adipocyte differentiation and subcutaneous fat deposition, improving insulin resistance and reducing visceral fat. Thiazolidinediones reproduce the effects of PPAR-γ activation and therefore increase the amount of subcutaneous fat while enhancing insulin sensitivity and reducing visceral fat. Partial or virtually complete lack of adipose tissue (lipodystrophy) is associated with insulin resistance and its clinical manifestations, including essential hypertension, hypertriglyceridemia, reduced HDL-c, type 2 diabetes, cardiovascular disease, and kidney disease. Patients with Prader Willi syndrome manifest severe subcutaneous obesity without insulin resistance. The impaired ability to accumulate fat in the subcutaneous adipose tissue may be due to deficient triglyceride synthesis, inadequate formation of lipid droplets, or defective adipocyte differentiation. Lean and obese humans develop insulin resistance when the capacity to store fat in the subcutaneous adipose tissue is exhausted and deposition of triglycerides is no longer attainable at that location. Existing adipocytes become large and reflect the presence of insulin resistance.

Genotype-phenotype associations in Alström syndrome: a systematic review and meta-analysis

BACKGROUND

Alström syndrome (ALMS; #203800) is an ultrarare monogenic recessive disease. This syndrome is associated with variants in the ALMS1 gene, which encodes a centrosome-associated protein involved in the regulation of several ciliary and extraciliary processes, such as centrosome cohesion, apoptosis, cell cycle control and receptor trafficking. The type of variant associated with ALMS is mostly complete loss-of-function variants (97%) and they are mainly located in exons 8, 10 and 16 of the gene. Other studies in the literature have tried to establish a genotype-phenotype correlation in this syndrome with limited success. The difficulty in recruiting a large cohort in rare diseases is the main barrier to conducting this type of study.

METHODS

In this study we collected all cases of ALMS published to date. We created a database of patients who had a genetic diagnosis and an individualised clinical history. Lastly, we attempted to establish a genotype-phenotype correlation using the truncation site of the patient's longest allele as a grouping criteria.

RESULTS

We collected a total of 357 patients, of whom 227 had complete clinical information, complete genetic diagnosis and meta-information on sex and age. We have seen that there are five variants with high frequency, with p.(Arg2722Ter) being the most common variant, with 28 alleles. No gender differences in disease progression were detected. Finally, truncating variants in exon 10 seem to be correlated with a higher prevalence of liver disorders in patients with ALMS.

CONCLUSION

Pathogenic variants in exon 10 of the ALMS1 gene were associated with a higher prevalence of liver disease. However, the location of the variant in the ALMS1 gene does not have a major impact on the phenotype developed by the patient.

Role of Alström syndrome 1 in the regulation of glomerular hemodynamics

Inactivating mutations in the ALMS1 gene in humans cause Alström syndrome, characterized by the early onset of obesity, insulin resistance, and renal dysfunction. However, the role of ALMS1 in renal function and hemodynamics is unclear. We previously found that ALMS1 is expressed in thick ascending limbs, where it binds and decreases Na+-K+-2Cl- cotransporter activity. We hypothesized that ALMS1 is expressed in macula densa cells and that its deletion enhances tubuloglomerular feedback (TGF) and reduces glomerular filtration rate (GFR) in rats. To test this, homozygous ALMS1 knockout (KO) and littermate wild-type Dahl salt-sensitive rats were studied. TGF sensitivity was higher in ALMS1 KO rats as measured by in vivo renal micropuncture. Using confocal microscopy, we confirmed immunolabeling of ALMS1 in macula densa cells (nitric oxide synthase 1 positive), supporting a role for ALMS1 in TGF regulation. Baseline glomerular capillary pressure was higher in ALMS1 KO rats, as was mean arterial pressure. Renal interstitial hydrostatic pressure was lower in ALMS1 KO rats, which is linked to increased Na+ reabsorption and hypertension. GFR was reduced in ALMS1 KO rats. Seven-week-old ALMS1 KO rats were not proteinuric, but proteinuria was present in 18- to 22-wk-old ALMS1 KO rats. The glomerulosclerosis index was higher in 18-wk-old ALMS1 KO rats. In conclusion, ALMS1 is involved in the control of glomerular hemodynamics in part by enhancing TGF sensitivity, and this may contribute to decreased GFR. Increased TGF sensitivity, enhanced glomerular capillary pressure, and hypertension may lead to glomerular damage in ALMS1 KO rats. These are the first data supporting the role of ALMS1 in TGF and glomerular hemodynamics.NEW & NOTEWORTHY ALMS1 is a novel protein involved in regulating tubuloglomerular feedback (TGF) sensitivity, glomerular capillary pressure, and blood pressure, and its dysfunction may reduce renal function and cause glomerular damage.

Genetic syndromes with diabetes: A systematic review

Previous reviews and clinical guidelines have identified 10-20 genetic syndromes associated with diabetes, but no systematic review has been conducted to date. We provide the first comprehensive catalog for syndromes with diabetes mellitus. We conducted a systematic review of MEDLINE, Embase, CENTRAL, PubMed, OMIM, and Orphanet databases for case reports, case series, and observational studies published between 1946 and January 15, 2020, that described diabetes mellitus in adults and children with monogenic or chromosomal syndromes. Our literature search identified 7,122 studies, of which 160 fulfilled inclusion criteria. Our analysis of these studies found 69 distinct diabetes syndromes. Thirty (43.5%) syndromes included diabetes mellitus as a cardinal clinical feature, and 56 (81.2%) were fully genetically elucidated. Sixty-three syndromes (91.3%) were described more than once in independent case reports, of which 59 (93.7%) demonstrated clinical heterogeneity. Syndromes associated with diabetes mellitus are more numerous and diverse than previously anticipated. While knowledge of the syndromes is limited by their low prevalence, future reviews will be needed as more cases are identified. The genetic etiologies of these syndromes are well elucidated and provide potential avenues for future gene identification efforts, aid in diagnosis and management, gene therapy research, and developing personalized medicine treatments.

Impaired Ca2+ signaling due to hepatic steatosis mediates hepatic insulin resistance in Alström syndrome mice that is reversed by GLP-1 analog treatment

Ca²⁺ signaling plays a critical role in the regulation of hepatic metabolism by hormones including insulin. Changes in cytoplasmic Ca²⁺ regulate synthesis and posttranslational modification of key signaling proteins in the insulin pathways. Emerging evidence suggests that hepatocyte intracellular Ca²⁺ signaling is altered in lipid-loaded liver cells isolated from obese rodent models. The mechanisms of altered Ca²⁺-insulin and insulin-Ca²⁺ signaling pathways in obesity remain poorly understood. Here, we show that the kinetics of insulin-initiated intracellular (initial) Ca²⁺ release from endoplasmic reticulum is significantly impaired in steatotic hepatocytes from obese Alström syndrome mice. Furthermore, exenatide, a glucagon-like peptide-1 (GLP-1) analog, reversed lipid-induced inhibition of intracellular Ca²⁺ release kinetics in steatotic hepatocytes, without affecting the total content of intracellular Ca²⁺ released. Exenatide reversed the lipid-induced inhibition of intracellular Ca²⁺ release, at least partially, via lipid reduction in hepatocytes, which then restored hormone-regulated cytoplasmic Ca²⁺ signaling and insulin sensitivity. This data provides additional evidence for the important role of Ca²⁺ signaling pathways in obesity-associated impaired hepatic lipid homeostasis and insulin signaling. It also highlights a potential advantage of GLP-1 analogs when used to treat type 2 diabetes associated with hepatic steatosis.

Monogenic Diabetes in Children and Adolescents: Recognition and Treatment Options

PURPOSE OF REVIEW

We provide a review of monogenic diabetes in young children and adolescents with a focus on recognition, management, and pharmacological treatment.

RECENT FINDINGS

Monogenic forms of diabetes account for approximately 1-2% of diabetes in children and adolescents, and its incidence has increased in recent years due to greater awareness and wider availability of genetic testing. Monogenic diabetes is due to single gene defects that primarily affect beta cell function with more than 30 different genes reported. Children with antibody-negative, C-peptide-positive diabetes should be evaluated and genetically tested for monogenic diabetes. Accurate genetic diagnosis impacts treatment in the most common types of monogenic diabetes, including the use of sulfonylureas in place of insulin or other glucose-lowering agents or discontinuing pharmacologic treatment altogether. Diagnosis of monogenic diabetes can significantly improve patient care by enabling prediction of the disease course and guiding appropriate management and treatment.

Alström syndrome: current perspectives

Alström syndrome (ALMS) is a rare genetic disorder that has been included in the ciliopathies group, in the last few years. Ciliopathies are a growing group of diseases associated with defects in ciliary structure and function. The development of more powerful genetic approaches has been replaced the strategies to follow for getting a successful molecular diagnosis for these patients, especially for those without the typical ALMS phenotype. In an effort to deepen the understanding of the pathogenesis of ALMS disease, much work has been done, in order to establish the biological implication of ALMS1 protein, which is still being elucidated. In addition to its role in ciliary function and structure maintenance, this protein has been implicated in intracellular trafficking, regulation of cilia signaling pathways, and cellular differentiation, among others. All these progresses will lead to identifying therapeutic targets, thus opening the way to future personalized therapies for human ciliopathies.

The phenotypic and molecular genetic spectrum of Alström syndrome in 44 Turkish kindreds and a literature review of Alström syndrome in Turkey

Alström syndrome (ALMS) is an autosomal recessive disease characterized by multiple organ involvement, including neurosensory vision and hearing loss, childhood obesity, diabetes mellitus, cardiomyopathy, hypogonadism, and pulmonary, hepatic, renal failure and systemic fibrosis. Alström Syndrome is caused by mutations in ALMS1, and ALMS1 protein is thought to have a role in microtubule organization, intraflagellar transport, endosome recycling and cell cycle regulation. Here, we report extensive phenotypic and genetic analysis of a large cohort of Turkish patients with ALMS. We evaluated 61 Turkish patients, including 11 previously reported, for both clinical spectrum and mutations in ALMS1. To reveal the molecular diagnosis of the patients, different approaches were used in combination, a cohort of patients were screened by the gene array to detect the common mutations in ALMS1 gene, then in patients having any of the common ALMS1 mutations were subjected to direct DNA sequencing or next-generation sequencing for the screening of mutations in all coding regions of the gene. In total, 20 distinct disease-causing nucleotide changes in ALMS1 have been identified, eight of which are novel, thereby increasing the reported ALMS1 mutations by 6% (8/120). Five disease-causing variants were identified in more than one kindred, but most of the alleles were unique to each single patient and identified only once (16/20). So far, 16 mutations identified were specific to the Turkish population, and four have also been reported in other ethnicities. In addition, 49 variants of uncertain pathogenicity were noted, and four of these were very rare and probably or likely deleterious according to in silico mutation prediction analyses. ALMS has a relatively high incidence in Turkey and the present study shows that the ALMS1 mutations are largely heterogeneous; thus, these data from a particular population may provide a unique source for the identification of additional mutations underlying Alström Syndrome and contribute to genotype-phenotype correlation studies.

A novel ALMS1 splice mutation in a non-obese juvenile-onset insulin-dependent syndromic diabetic patient

Insulin-dependent juvenile-onset diabetes may occur in the context of rare syndromic presentations suggesting monogenic inheritance rather than common multifactorial autoimmune type 1 diabetes. Here, we report the case of a Lebanese patient diagnosed with juvenile-onset insulin-dependent diabetes presenting ketoacidosis, early-onset retinopathy with optic atrophy, hearing loss, diabetes insipidus, epilepsy, and normal weight and stature, who later developed insulin resistance. Despite similarities with Wolfram syndrome, we excluded the WFS1 gene as responsible for this disease. Using combined linkage and candidate gene study, we selected ALMS1, responsible for Alström syndrome, as a candidate gene. We identified a novel splice mutation in intron 18 located 3 bp before the intron-exon junction (IVS18-3T>G), resulting in exon 19 skipping and consequent frameshift generating a truncated protein (V3958fs3964X). The clinical presentation of the patient significantly differed from typical Alström syndrome by the absence of truncal obesity and short stature, and by the presence of ketoacidotic insulin-dependent diabetes, optic atrophy and diabetes insipidus. Our observation broadens the clinical spectrum of Alström syndrome and suggests that ALMS1 mutations may be considered in patients who initially present with an acute onset of insulin-dependent diabetes.

The progression from obesity to type 2 diabetes in Alström syndrome

BACKGROUND

Alström syndrome (ALMS) is a rare autosomal recessive monogenic disease associated with obesity, hyperinsulinemia, and alterations of glucose metabolism that often lead to the development of type 2 diabetes at a young age.

OBJECTIVE

To study the relationship between weight and metabolism in a group of ALMS patients and matched controls.

RESEARCH DESIGN AND METHODS

Fifteen ALMS patients (eight males, seven females; aged 3-51) were compared in a cross-sectional study with an age- and weight-matched control population. Anthropometric parameters, fat mass, glucose and insulin secretion in basal and dynamic oral glucose tolerance test (OGTT) conditions were measured. Furthermore, anthropometric and body composition data were obtained from an international group of 27 ALMS patients (13 males, 14 females, age range: 4-29 yr).

RESULTS

In ALMS we observed an inverse correlation between age and standard deviation scores for height, weight, and body mass index. The OGTT glycemic curves of ALMS subjects were similar to those of age-matched controls, whereas insulin response was clearly greater. In ALMS individuals the insulin response showed a reduction with age. We documented pathologic values of the derived indices homeostasis model assessment of insulin resistance (HOMA-IR), insulin sensitivity index, HOMA%β-cell and insulinogenic index in ALMS, but unlike the insulin-resistance indices, the β-cell function indices showed a significant reduction with age.

CONCLUSIONS

In ALMS the progression from the early onset obesity toward the impaired fasting glucose or impaired glucose tolerance and overt diabetes is mostly because of a progressive failure of β-cell insulin secretion without any further worsening of insulin resistance with age, even in the presence of weight reduction.

Presentation and course of diabetes in children and adolescents with Alstrom syndrome

Alstrom syndrome is characterized by childhood obesity, progressive retinal degeneration, and sensorineural hearing loss with diabetes mellitus (DM) developing later in childhood and adulthood. The course of diabetes in children with this condition has not been described. We aim to describe the diagnosis, management, and course of diabetes in a series of children followed in our center. A retrospective chart review of all seven children with Alstrom syndrome was performed. Patients, aged 4.5-22 yr, had typical features of Alstrom syndrome. Five were diagnosed with DM at a median age of 11.5 yr. At diagnosis of DM, mean fasting blood glucose (FBG) was normal at 82.8 ± 12.6 mg/dL (4.6 ± 0.7 mmol/L), but random or oral glucose tolerance test (OGTT) values were > 200 mg/dL (11.1 mmol/L). Two patients had periods of poor control despite high-dose insulin and show better A1C, off insulin and with other therapy. In our series, DM in Alstrom syndrome begins by age 14 yr. At diagnosis of DM, FBG was normal. Hence the diagnosis may be missed if screening is performed with FBG alone. We conclude that OGTT should be considered annually from age 6 to 7 yr and in established DM, if glycemic control is poor on insulin, escalating doses may not be effective.

Alström syndrome: genetics and clinical overview

Alström syndrome is a rare autosomal recessive genetic disorder characterized by cone-rod dystrophy, hearing loss, childhood truncal obesity, insulin resistance and hyperinsulinemia, type 2 diabetes, hypertriglyceridemia, short stature in adulthood, cardiomyopathy, and progressive pulmonary, hepatic, and renal dysfunction. Symptoms first appear in infancy and progressive development of multi-organ pathology leads to a reduced life expectancy. Variability in age of onset and severity of clinical symptoms, even within families, is likely due to genetic background.Alström syndrome is caused by mutations in ALMS1, a large gene comprised of 23 exons and coding for a protein of 4,169 amino acids. In general, ALMS1 gene defects include insertions, deletions, and nonsense mutations leading to protein truncations and found primarily in exons 8, 10 and 16. Multiple alternate splice forms exist. ALMS1 protein is found in centrosomes, basal bodies, and cytosol of all tissues affected by the disease. The identification of ALMS1 as a ciliary protein explains the range of observed phenotypes and their similarity to those of other ciliopathies such as Bardet-Biedl syndrome.Studies involving murine and cellular models of Alström syndrome have provided insight into the pathogenic mechanisms underlying obesity and type 2 diabetes, and other clinical problems. Ultimately, research into the pathogenesis of Alström syndrome should lead to better management and treatments for individuals, and have potentially important ramifications for other rare ciliopathies, as well as more common causes of obesity and diabetes, and other conditions common in the general population.

Alström syndrome: insights into the pathogenesis of metabolic disorders

Genetic causes of obesity include the ciliopathies Alström syndrome and Bardet-Biedl syndrome. In these disorders, mutations cause dysfunction of the primary cilium, an organelle involved in intracellular and intercellular sensing and signaling. Alström syndrome is an autosomal-recessive disorder caused solely by mutations in ALMS1. By contrast, Bardet-Biedl syndrome is caused by mutations in at least 14 genes involved in primary cilium function. Despite equivalent levels of obesity, patients with Alström syndrome are more likely than those with Bardet-Biedl syndrome to develop childhood type 2 diabetes mellitus (T2DM), suggesting that ALMS1 might have a specific role in β-cell function and/or peripheral insulin signaling pathways. How mutations in genes that encode proteins involved in primary cilium function lead to the clinical phenotypes of these syndromes is being revealed by work in mutant mouse models. With the aid of these models, insights are being obtained into the pathogenic mechanisms that underlie obesity, insulin resistance and T2DM. Research into ciliopathies, including Alström syndrome and Bardet-Biedl syndrome, should lead not only to improved treatments for individuals with these genetic disorders, but also to improved understanding of the cellular pathways involved in other common causes of obesity and T2DM.

Alstrom syndrome (OMIM 203800): a case report and literature review

Background

Alstrom syndrome (AS) is a rare autosomal recessive disease characterized by multiorgan dysfunction. The key features are childhood obesity, blindness due to congenital retinal dystrophy, and sensorineural hearing loss. Associated endocrinologic features include hyperinsulinemia, early-onset type 2 diabetes, and hypertriglyceridemia. Thus, AS shares several features with the common metabolic syndrome, namely obesity, hyperinsulinemia, and hypertriglyceridemia. Mutations in the ALMS1 gene have been found to be causative for AS with a total of 79 disease-causing mutations having been described.

Case presentation

We describe the case of a 27-year old female from an English (Caucasian) kindred. She had been initially referred for hypertriglyceridemia, but demonstrated other features suggestive of AS, including blindness, obesity, type 2 diabetes, renal dysfunction, and hypertension. DNA analysis revealed that she is a compound heterozygote with two novel mutations in the ALMS1 gene – H3882Y and V424I. Examination of her family revealed that her phenotypically unaffected mother and younger sister also had heterozygous mutations in the ALMS1 gene. In addition to presenting these novel molecular findings for AS, we review the clinical and genetic features of AS in the context of our case.

Conclusion

Two novel mutations in the ALMS1 gene causative for AS have been reported here, thereby increasing the number of reported mutations to 81 and providing a wider basis for mutational screening among affected individuals.

Molecular analysis and long-term clinical evaluation of three siblings with Alström syndrome

Alström syndrome is a rare, autosomal recessive disorder characterized by a wide spectrum of clinical features including early-onset retinal degeneration leading to blindness, sensorineural hearing loss, short stature, obesity, type 2 diabetes, hyperlipidemia and dilated cardiomyopathy. Renal, hepatic and pulmonary dysfunction may occur in the later phases of the disease. The three affected sisters, from a consanguineous Turkish family, with the characteristic features of Alström syndrome, were clinically diagnosed in 1987 and followed for 20 years. DNA sequence analysis of ALMS1, the causative gene in Alström syndrome, identified a novel homozygous disease-causing mutation, c.8164C>T, resulting in a premature termination codon in exon 10 in each of the three affected sisters. Furthermore, we describe the longitudinal disease progression in this family and report new clinical findings likely associated with Alström syndrome, such as pes planus and hyperthyroidism.

Effect of metformin and rosiglitazone in a prepubertal boy with Alström syndrome

Alström syndrome (AS) is an autosomal recessive disorder characterized by progressive pigmentary retinopathy, sensorineural hearing loss, fatty liver infiltration, obesity, insulin resistance and early-onset type 2 diabetes mellitus (DM2). Early onset of insulin resistance and DM2 are key components of this syndrome.

AIM

To study the effect of early initiation of the insulin sensitizer metformin combined with rosiglitazone in a patient with AS with impaired glucose tolerance.

PATIENT

An 8 year-old boy with AS presented with acanthosis nigricans and insulin resistance at the age of 6 years. He had progressive excessive weight gain from 9 months of age. By the age of 1 year he developed photosensitivity, blindness and nystagmus. At the age of 5.5 years, his body mass index (BMI) was above the 95th percentile. He developed impaired glucose tolerance at 6 years of age and treatment with metformin was initiated. After 8 months of treatment with metformin he developed DM2. The dose of metformin was increased, and rosiglitazone added.

METHODS

A 2-hour oral glucose tolerance test (OGTT) and a rapid intravenous glucose tolerance test (IVGTT) were performed before treatment was initiated, after treatment with metformin and at the end of 1 year of combination therapy with metformin and rosiglitazone to calculate quantitative insulin sensitivity check index (QUICKI) and acute insulin response (AIR). For mutation analysis, all exons and splice site sequences of the ALMS1 gene were amplified and sequenced.

RESULTS

Metformin treatment alone at the stage of impaired glucose tolerance did not prevent progression to DM2. However, metformin at a higher dose and in combination with rosiglitazone resulted in improvement of pancreatic beta-cell function, shown by markedly improved first-phase insulin response to glucose measured by AIR. The patient was found to have two heterozygous nonsense mutations in ALMS1, 8008 C-->T Ter, R2670X, and 11449 C-->T Ter, Q3817X. These alterations cause premature stops and result in a truncated ALMS1 protein.

CONCLUSION

We suggest that early initiation of combined therapy comprising a high dose of metformin plus rosiglitazone may be valuable in managing insulin resistance and DM2 in children with AS.

Pediatric nonalcoholic fatty liver disease (NAFLD): a "growing" problem?

Nonalcoholic fatty liver disease (NAFLD) can affect both adults and children. With the current worldwide epidemic of pediatric obesity, pediatric NAFLD is increasingly being diagnosed. It is not exactly identical to NAFLD in adults, and these differences may be due in part to the occurrence of hepatic metabolic derangements typical of NAFLD during periods of active growth (infancy, mid-childhood and puberty). The natural history of pediatric NAFLD is not yet known; however, children with pediatric NAFLD can develop cirrhosis. Although details of disease mechanism in pediatric NAFLD remain unclear, hyperinsulinemia with insulin resistance appears to be critical. Determining the pathogenesis of pediatric NAFLD is likely to enhance our understanding of NAFLD in all age groups and may identify new treatment opportunities. Finding effective ways to prevent pediatric NAFLD is an important issue for children's health.

Is arterial stiffening in Alström syndrome linked to the development of cardiomyopathy?

BACKGROUND

Alström syndrome (AS) is a rare autosomal recessive condition characterized by retinal degeneration, childhood obesity, and severe insulin resistance. Dilated cardiomyopathy of unknown aetiology is a well-recognized and potentially lethal complication. The aim of this study was to investigate the relationship between vascular function, hyperinsulinaemia and cardiac performance in AS.

MATERIALS AND METHODS

Fifteen subjects with AS (mean age 21 years, range 10-35) were studied and compared with age-, sex-, and blood pressure-matched healthy controls. Large artery stiffness and wave reflections were assessed in both groups by measuring aortic and brachial pulse wave velocity (PWV) (carotid-femoral and carotid-radial) and augmentation index (AIX) (Sphygmocor). In AS subjects, left ventricular function was assessed by echocardiography and metabolic parameters including fasting insulin, glucose, lipids and brain natriuretic peptide were also measured.

RESULTS

Comparing AS subjects vs. controls (mean +/- SD), AIX was elevated in AS subjects (18 +/- 9% vs. 3 +/- 11%, P < 0.0001). No significant changes in brachial PWV (8.1 +/- 1.3 m s(-1) vs. 7.3 +/- 1.1 m s(-1), P = 0.14) or aortic PWV (6.5 +/- 1.1 m s(-1) vs. 6.0 +/- 1.0 m s(-1), P = 0.26) were observed. AS subjects were hyperinsulinaemic and had disturbances in lipid profiles relative to controls. No correlations were observed between vascular, metabolic and echocardiographic parameters.

CONCLUSIONS

In AS there are alterations in the shape of the central arterial pressure waveform associated with augmented aortic systolic pressure and indicative of increased wave reflection. Unfavourable central arterial haemodynamics in AS may contribute to the development of cardiomyopathy but other aetiological factors are probably involved.

Non-alcoholic steatohepatitis in children

Non-alcoholic steatohepatitis (NASH) is an important liver disease in children; it can cause cirrhosis in children. The disease mechanism involves hepatic insulin resistance with hyperinsulinemia and changes in certain adipocytokines and inflammatory mediators. The differential diagnosis of childhood NASH includes metabolic disorders, drug hepatotoxicity, and alcoholic hepatitis in adolescent patients. The histologic features in childhood NASH often differ from those in adults who have NASH. Treatment is gradual weight loss through changes in food intake patterns and increased levels of physical activity; the role of drug treatment of NASH in children is an area of ongoing research.

Rare case of Alstrom syndrome without obesity and with short stature, diagnosed in adulthood

Alstrom syndrome is a rare autosomal recessive disorder characterized by retinal degeneration, sensorineural hearing loss, obesity, type 2 diabetes mellitus and chronic nephropathy. It may be associated with acanthosis nigricans, hypergonadotropic hypogonadism, hepatic dysfunction, hepatic steatosis, hyperlipidaemia, dilated cardiomyopathy and short stature. We report a patient with Alstrom syndrome who had hypergonadotropic hypogonadism, hepatic dysfunction, hepatic steatosis and short stature with normal body weight, all of which are seen infrequently with this syndrome.

Syndromic obesity and diabetes: changes in body composition with age and mutation analysis of ALMS1 in 12 United Kingdom kindreds with Alstrom syndrome

CONTEXT

Alström syndrome (AS) is a monogenic form of infancy-onset obesity and insulin resistance, caused by ALMS1 mutations. The natural history of the insulin resistance is unknown, in particular how this relates to changes in body composition. It is also unclear how ALMS1 mutations relate to the characteristic phenotype.

OBJECTIVES

Our objectives were to characterize body composition and metabolic parameters, to establish ALMS1 mutation spectrum of United Kingdom AS patients, and to determine whether a genotype-phenotype correlation exists.

DESIGN AND PATIENTS

We conducted a cross-sectional cohort study of 12 unrelated subjects with AS. Age-standardized body composition was assessed by anthropometry and dual-energy x-ray absorptiometry and insulin sensitivity by homeostasis model assessment. The exons and intron-exon boundaries of ALMS1 were directly sequenced.

SETTING

The study was performed during the annual Alström Syndrome UK multidisciplinary screening clinic.

RESULTS

AS patients have early-onset obesity, but body mass index, waist circumference, and body fat from dual-energy x-ray absorptiometry were negatively correlated with age (r = -0.37, P = 0.2; r = -0.84, P = 0.002; and r = -0.6, P = 0.05). Despite this, insulin resistance increased, demonstrated by raised fasting insulin and fall in homeostasis model assessment insulin sensitivity with age (r = -0.64, P = 0.02). ALMS1 mutations were identified in 10 of 12 patients, with a potential founder mutation in exon 16 present in five [np 10775del (C); Del3592fs/ter3597]. No genotype-phenotype correlation was observed.

CONCLUSIONS

We identified mutations in ALMS1 in more than 80% of patients with no genotype-phenotype correlation. In AS, severe childhood obesity, waist circumference, and body fat decrease with age, whereas insulin resistance increases. The abdominal obesity, insulin resistance, diabetes, hypertriglyceridemia, and hypertension suggest that AS could represent a monogenic model for the metabolic syndrome.

Fat aussie--a new Alström syndrome mouse showing a critical role for ALMS1 in obesity, diabetes, and spermatogenesis

Mutations in the human ALMS1 gene are responsible for Alström syndrome, a disorder in which key metabolic and endocrinological features include childhood-onset obesity, metabolic syndrome, and diabetes, as well as infertility. ALMS1 localizes to the basal bodies of cilia and plays a role in intracellular trafficking, but the biological functions of ALMS1 and how these relate to the pathogenesis of obesity, diabetes, and infertility remain unclear. Here we describe a new mouse model of Alström syndrome, fat aussie, caused by a spontaneous mutation in the Alms1 gene. Fat aussie (Alms1 foz/foz) mice are of normal weight when young but, by 120 d of age, they become obese and hyperinsulinemic. Diabetes develops in Alms1 foz/foz mice accompanied by pancreatic islet hyperplasia and islet cysts. Female mice are fertile before the onset of obesity and metabolic syndrome; however, male fat aussie mice are sterile due to a progressive germ cell loss followed by an almost complete block of development at the round-to-elongating spermatid stage of spermatogenesis. In conclusion, Alms1 foz/foz mouse is a new animal model in which to study the pathogenesis of the metabolic and fertility defects of Alström syndrome, including the role of ALMS1 in appetite regulation, pathogenesis of the metabolic syndrome, pancreatic islet physiology, and spermatogenesis.

Acquired non-type 1 diabetes in childhood: subtypes, diagnosis, and management

Over the past 30 years it has become apparent that not all diabetes presenting in childhood is autoimmune type 1. Increasingly type 2 diabetes, maturity onset diabetes of the young, iatrogenic diabetes, and rare syndromic forms of diabetes such as Wolfram's syndrome have been identified in children. This review is aimed at the general paediatrician looking after children with diabetes, and aims to provide an algorithm for assessment, investigation, and suggested management for the newly diagnosed child with suspected non-type 1 diabetes. This article will also be relevant to the child with atypical diabetes-that is, on low insulin doses outside the honeymoon period.

Metabolic effects of growth hormone therapy in an Alström syndrome patient

AIM

To investigate the metabolic effects of recombinant human growth hormone (rhGH) in an Alström syndrome patient with growth hormone deficiency.

METHODS

A 15-year-old Alström syndrome boy with growth hormone deficiency received rhGH therapy for 1 year. Biochemical parameters, including hepatic enzyme levels, lipid profiles, and insulin sensitivity, were measured. Body composition analysis and computed tomography scans of the liver were performed.

RESULTS

After 1 year of rhGH treatment, body fat mass, fat infiltration in the liver, and serum lipid profiles had all decreased. Insulin sensitivity and acanthosis nigricans improved.

CONCLUSION

rhGH therapy might have beneficial effects on body composition, liver fat content, lipid profiles, and insulin resistance in Alström syndrome patients, with improvement of the glucose homeostasis.

A mild form of Alstrom disease associated with metabolic syndrome and very high fasting serum free fatty acids: two cases diagnosed in adult age

Alstrom syndrome (ALMS) is a very rare genetic autosomal recessive disease, characterized by early-onset severe abdominal obesity, impaired glucose tolerance or type 2 diabetes with insulin resistance, acanthosis nigricans, hyperlipidemia, childhood progressive retinal degeneration or retinitis pigmentosa and neurosensory hearing loss or deafness, cardiomyopathy, and other endocrine disorders. Genetic studies locate the ALMS gene on chromosome 2p12-13. The aim of this paper is to describe and discuss two unrelated cases of a mild ALMS form diagnosed after the age of 40 and 60, respectively, in adult fertile female patients. These cases showed several features of the disease plus other alterations characteristic of the classic "metabolic syndrome," including hypertension, hyperfibrinogenemia, and thrombotic states. Moreover, the patients had very high fasting serum free fatty acid (FFA) levels (2150 and 1919 micromol/L, respectively), which proved to be sensitive to inhibition by oral glucose tolerance test (OGTT)-induced hyperinsulinemia as well as to caloric restriction. ALMS may have an adverse prognosis and is often underdiagnosed. Its mild form, which allows a long survival, may also be associated with the late complications of the metabolic syndrome, leading to increased vascular risk.

Hypertriglyceridaemia in Alström's syndrome: causes and associations in 37 cases

OBJECTIVE

To document frequency of severe hypertriglyceridaemia in Alström's syndrome (AS) and its relationship to hepatic and renal function, glycaemia and insulin resistance.

PATIENTS AND METHODS

Thirty-seven subjects with AS aged 5-35 years, 51% male, were assessed at multidisciplinary clinics in Canada, UK and Italy. Diagnostic criteria were: severe cone/rod dystrophy leading to severe visual impairment in early childhood, sensorineural deafness, moderate overall obesity and normal intelligence. Three patients were treated with thyroxine for primary hypothyroidism and one female patient for secondary amenorrhoea with 20 micro g ethinyloestradial combined oral contraceptive. Two male patients were receiving monthly intramuscular testosterone enanthate for secondary hypogonadism. Fasting bloods were taken for serum insulin, serum glucose, serum triglycerides, hepatic and renal function and glycosylated Hb. Triglyceride levels > 8 mmol/l and fasting serum insulin levels > 16 microunits/ml were considered to represent severe hypertriglyceridaemia and severe insulin resistance, respectively. All subjects with (23) hypertriglyceridaemia also had high insulin resistance, as measured by HOMA modelling. However, there was no significant correlation between log tyriglyceride and log serum insulin or HOMA in the whole group (P = 0.2 and 0.14, respectively). There was no clear relationship between serum triglyceride levels and age, body mass index (BMI), hepatic or renal impairment or glycaemia.

CONCLUSION

The first overview of serum triglyceride levels in a significant number of reported cases of Alström Syndrome shows an overlap between severe hypertriglyceridaemia and severe hyperinsulinism, but not a direct correlation between the two nor with insulin resistance measured by HOMA. Triglyceride levels were not related to glycaemia, hepatic or renal dysfunction.

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.