Roux-en-Y gastric bypass in an adolescent patient with Bardet-Biedl syndrome, a monogenic obesity disorder

Bardet-Biedl syndrome: A clinical overview focusing on diagnosis, outcomes and best-practice management

Bardet-Biedl syndrome (BBS) is a genetic disorder characterized by early-onset obesity, polydactyly, genital and kidney anomalies, developmental delay and vision loss due to rod-cone dystrophy. BBS is an autosomal recessive disorder with >20 implicated genes. The genotype-phenotype relationship in BBS is not clear, and there may be additional modifying factors. The underlying mechanism is dysfunction of primary cilia. In BBS, receptor trafficking in and out of the cilia is compromised, affecting multiple organ systems. Along with early-onset obesity, hyperphagia is a prominent symptom and contributes significantly to clinical morbidity and caregiver burden. While there is no cure for BBS, setmelanotide is a new pharmacotherapy approved for treatment of obesity in BBS. The differential diagnosis for BBS includes other ciliopathies, such as Alstrom syndrome, and other genetic obesity syndromes, such as Prader-Willi syndrome. Careful clinical history and genetic testing can help determine the diagnosis and a multidisciplinary team is necessary to guide clinical management.

Bardet-Biedl syndrome: A focus on genetics, mechanisms and metabolic dysfunction

Bardet-Biedl syndrome (BBS) is a rare, monogenic, multisystem disorder characterized by retinal dystrophy, renal abnormalities, polydactyly, learning disabilities, as well as metabolic dysfunction, including obesity and an increased risk of type 2 diabetes. It is a primary ciliopathy, and causative mutations in more than 25 different genes have been described. Multiple cellular mechanisms contribute to the development of the metabolic phenotype associated with BBS, including hyperphagia as a consequence of altered hypothalamic appetite signalling as well as alterations in adipocyte biology promoting adipocyte proliferation and adipogenesis. Within this review, we describe in detail the metabolic phenotype associated with BBS and discuss the mechanisms that drive its evolution. In addition, we review current approaches to the metabolic management of patients with BBS, including the use of weight loss medications and bariatric surgery. Finally, we evaluate the potential of targeting hypothalamic appetite signalling to limit hyperphagia and induce clinically significant weight loss.

Management of Monogenic and Syndromic Obesity

Similar to the general population, lifestyle interventions focused on nutrition and physical activity form the foundation for treating obesity caused by rare genetic disorders. Additional therapies, including metreleptin and setmelanotide, that target defects within the leptin signaling pathway can effectively synergize with lifestyle efforts to treat monogenic disorders of leptin, leptin receptor, proopiomelanocortin (POMC), and proprotein convertase subtilisin/kexin type 1 (PCSK1) and syndromic conditions, such as the ciliopathies Bardet-Biedl and Alström syndromes, whose pathophysiological mechanisms also converge on the leptin pathway. Investigational treatments for Prader-Willi syndrome target specific defects caused by reduced expression of paternally derived genes within the chromosome 15q region.

Towards precision medicine in bariatric surgery prescription

Obesity is a complex, multifactorial and chronic disease. Bariatric surgery is a safe and effective treatment intervention for obesity and obesity-related diseases. However, weight loss after surgery can be highly heterogeneous and is not entirely predictable, particularly in the long-term after intervention. In this review, we present and discuss the available data on patient-related and procedure-related factors that were previously appointed as putative predictors of bariatric surgery outcomes. In addition, we present a critical appraisal of the available evidence on which factors could be taken into account when recommending and deciding which bariatric procedure to perform. Several patient-related features were identified as having a potential impact on weight loss after bariatric surgery, including age, gender, anthropometrics, obesity co-morbidities, eating behavior, genetic background, circulating biomarkers (microRNAs, metabolites and hormones), psychological and socioeconomic factors. However, none of these factors are sufficiently robust to be used as predictive factors. Overall, there is no doubt that before we long for precision medicine, there is the unmet need for a better understanding of the socio-biological drivers of weight gain, weight loss failure and weight-regain after bariatric interventions. Machine learning models targeting preoperative factors and effectiveness measurements of specific bariatric surgery interventions, would enable a more precise identification of the causal links between determinants of weight gain and weight loss. Artificial intelligence algorithms to be used in clinical practice to predict the response to bariatric surgery interventions could then be created, which would ultimately allow to move forward into precision medicine in bariatric surgery prescription.

Genetic Contributors to Obesity

Genetic forms of obesity contribute to ∼7% of severe obesity in children and adolescents. The exact global prevalence of monogenic and syndromic forms of obesity is not well established, most likely due to missed or delayed diagnosis. The challenge in determining the prevalence can be attributed to the lack of consensus on identifying and evaluating symptoms of genetic defects in a timely manner and hence a vastly undertested patient population. Further large-scale and long-term studies are needed to advance the understanding of this unique phenotype of obesity and effective treatment options."

Laparoscopic Sleeve Gastrectomy in a Morbidly Obese Pediatric Patient With Bardet-Biedl Syndrome

Data on the effect of bariatric surgery for syndromic obesity are lacking. This case report presents the preoperative evaluation and perioperative outcomes of a 7-year-old pediatric patient with Bardet-Biedl syndrome (BBS) who underwent sleeve gastrectomy. The male patient was referred to our department for the surgical treatment of his obesity. His preoperative body mass index (BMI) was 55.2 kg/m² (weight, 83.5 kg), and he was above the 99^th percentile for age and gender. The patient underwent laparoscopic sleeve gastrectomy. The postoperative period was uneventful. Six months after the operation, the patient's weight decreased to 50 kg (BMI, 28.72 kg/m²). Weight loss was maintained until 3 years after surgery. Dyslipidemia and nonalcoholic fatty liver disease were significantly alleviated. Laparoscopic sleeve gastrectomy may be a safe and effective treatment for morbid BBS-related obesity in pediatric patients. Further data are needed to confirm the long-term efficacy and safety of bariatric surgery in BBS.

Monitoring and Management of Bardet-Biedl Syndrome: What the Multi-Disciplinary Team Can Do

Bardet – Biedl syndrome is a rare autosomal recessive multisystem non-motile ciliopathy. It has heterogeneous clinical manifestations. It is caused by mutations in 26 genes encoding BBSome proteins, chaperonines, and IFT complex. The main clinical features are: retinal cone-rod dystrophy, central obesity, postaxial polydactyly, cognitive impairment, hypogonadism and genitourinary anomalies, and kidney disease. The onset of clinical manifestations is variable which makes the diagnosis difficult in some patients. Because of the multiple system involvement, a multidisciplinary approach is necessary. The purpose of this review is to provide monitoring and management directions for a better approach to these patients.

Critical review of bariatric surgical outcomes in patients with Prader-Willi syndrome and other hyperphagic disorders

OBJECTIVE

The aim of this study was to review bariatric procedure outcomes among patients with Prader-Willi syndrome (PWS), melanocortin 4 receptor (MC4R) mutations, Bardet-Biedl syndrome, and hypothalamic obesity.

METHODS

Systematic published literature review used the following search terms: "Prader-Willi syndrome," "Bardet-Biedl syndrome," "hyperphagia," "bariatric surgery," "MC4R"/"melanocortin 4 receptor", "hypothalamic obesity," and "bariatric procedure." Information collected included demographics, genetics, anthropometry, procedure type, outcomes, and complications, with inclusion of case series and clinical reports given the rarity of the disorders. For PWS, postoperative weight-change percentage and BMI up to 14 years following surgery were analyzed using general linear mixed models, with descriptive outcomes for other conditions.

RESULTS

A total of 54 publications were identified, with variable follow-up periods for 202 patients (114 with PWS, 43 with MC4R mutations, 7 with Bardet-Biedl syndrome, and 38 with hypothalamic obesity) among bariatric procedures. Weight loss of patients with PWS was greatest within 1 year of surgery, with weight-change percentage not significantly different from 0 at 5 years. Long-term results in other conditions were variable and featured suboptimal weight loss and increased reoperation risk.

CONCLUSIONS

Bariatric procedures among hyperphagic individuals, including those with PWS, report variable results and outcomes. Benefits of bariatric surgery may be less durable in hyperphagic disorders in comparison with other patients with severe obesity.

Evaluation and Management of Early Onset Genetic Obesity in Childhood

One in five children and adolescents in the United States are diagnosed with obesity and nearly 6% of them are being classified under the severe obesity category. With over 7% of severe obesity being attributed to genetic disorders, in this review we aim to focus on monogenic and syndromic obesity: its etiology, wide spectrum of clinical presentation, criticalness of early identification, and limited management options. Advanced genetic testing methods including microarray and whole genome sequencing are imperative to identify the spectrum of mutations and develop targeted treatment strategies including personalized multidisciplinary care, use of investigational drugs, and explore surgical options in this unique subset of severe pediatric obesity.

Bardet-Biedl syndrome: Weight patterns and genetics in a rare obesity syndrome

BACKGROUND

Bardet-Biedl syndrome (BBS) is a rare genetic disorder that severely inhibits primary cilia function. BBS is typified by obesity in adulthood, but pediatric weight patterns, and thus optimal periods of intervention, are poorly understood.

OBJECTIVES

To examine body mass differences by age, gender, and genotype in children and adolescents with BBS.

METHODS

We utilized the largest international registry of BBS phenotypes. Anthropometric and genetic data were obtained from medical records or participant/family interviews. Participants were stratified by age and sex categories. Genotype and obesity phenotype were investigated in a subset of participants with available data.

RESULTS

Height and weight measurements were available for 552 unique individuals with BBS. The majority of birth weights were in the normal range, but rates of overweight or obesity rapidly increased in early childhood, exceeding 90% after age 5. Weight z-scores in groups >2 years were above 2.0, while height z-scores approached 1.0, but were close to 0.0 in adolescents. Relative to those with the BBS10 genotype, the BBS1 cohort had a lower BMI z-score in the 2-5 and 6-11 age groups, with similar BMI z-scores thereafter. Children with biallelic loss of function (LOF) genetic variants had significantly higher BMI z-scores compared to missense variants.

CONCLUSION

Despite normal birth weight, most individuals with BBS experience rapid weight gain in early childhood, with high rates of overweight/obesity sustained through adolescence. Children with LOF variants are disproportionally affected. Our findings support the need for earlier recognition and initiation of weight management therapies in BBS.

Bariatric Surgery for Monogenic Non-syndromic and Syndromic Obesity Disorders

PURPOSE OF REVIEW

The global prevalence of obesity has increased rapidly over the last decades, posing a severe threat to human health. Currently, bariatric surgery is the most effective therapy for patients with morbid obesity. It is unknown whether this treatment is also suitable for patients with obesity due to a confirmed genetic defect (genetic obesity disorders). Therefore, this review aims to elucidate the role of bariatric surgery in the treatment of genetic obesity.

RECENT FINDINGS

In monogenic non-syndromic obesity, an underlying genetic defect seems to be the most important factor determining the efficacy of bariatric surgery. In syndromic obesity, bariatric surgery result data are scarce, and even though some promising follow-up results have been reported, caution is required as patients with more severe behavioral and developmental disorders might have poorer outcomes. There is limited evidence in support of bariatric surgery as a treatment option for genetic obesity disorders; hence, no strong statements can be made regarding the efficacy and safety of these procedures for these patients. However, considering that patients with genetic obesity often present with life-threatening obesity-related comorbidities, we believe that bariatric surgery could be considered a last-resort treatment option in selected patients.

Managing Bardet-Biedl Syndrome-Now and in the Future

Bardet-Biedl syndrome is a rare autosomal recessive multisystem disorder caused by defects in genes encoding for proteins that localize to the primary cilium/basal body complex. Twenty-one disease-causing genes have been identified to date. It is one of the most well-studied conditions in the family of diseases caused by defective cilia collectively known as ciliopathies. In this review, we provide an update on diagnostic developments, clinical features, and progress in the management of Bardet-Biedl syndrome. Advances in diagnostic technologies including exome and whole genome sequencing are expanding the spectrum of patients who are diagnosed with Bardet-Biedl syndrome and increasing the number of cases with diagnostic uncertainty. As a result of the diagnostic developments, a small number of patients with only one or two clinical features of Bardet-Biedl syndrome are being diagnosed. Our understanding of the syndrome-associated renal disease has evolved and is reviewed here. Novel interventions are developing at a rapid pace and are explored in this review including genetic therapeutics such as gene therapy, exon skipping therapy, nonsense suppression therapy, and gene editing. Other non-genetic therapies such as gene repurposing, targeted therapies, and non-pharmacological interventions are also discussed.

Beneficial Outcomes of Sleeve Gastrectomy in a Morbidly Obese Patient With Bardet-Biedl Syndrome

Context

Severe obesity is one of the major features of Bardet-Biedl syndrome (BBS) and causes reduced life expectancy. Bariatric surgery is an effective treatment of morbid obesity. Data on the effect of bariatric surgery for monogenic obesity is essentially lacking. We present the clinical and metabolic 3-year follow-up of sleeve gastrectomy in a BBS patient.

Case Description

A 37-year-old obese woman with BBS (body mass index, 40 kg/m²) was referred to our clinic for uncontrolled diabetes, dyslipidemia, hypertension, and nonalcoholic fatty liver disease (NAFLD). After sleeve gastrectomy, progressive weight loss was observed, with a 32% total weight loss at 3-year follow-up. Glycemic control and NAFLD improved significantly. Blood pressure normalized, and treatment was discontinued 3 months after surgery.

Conclusions

Laparoscopic sleeve gastrectomy can be a safe and effective treatment of morbid BBS-related obesity in adult patients. Significant and sustained weight loss leads to the improvement of several obesity-related comorbidities such as diabetes, hypertension, and NAFLD, as in polygenic obesity. Further data are needed to confirm the long-term efficacy and safety of bariatric surgery in BBS.

Renal transplantation in Bardet-Biedl Syndrome

BACKGROUND

Renal anomalies are common in patients with Bardet-Biedl syndrome (BBS), a renal cystic ciliopathy with multi-systemic features. Renal transplantation is indicated in cases of end-stage renal disease (ESRD), but transplant centers may be hesitant to perform the necessary transplant in light of the multitude of metabolic comorbidities these patients often face with the potential to complicate outcomes.

METHODS

Data from the Clinical Registry Investigating BBS (CRIBBS) were used to investigate renal transplant outcomes in the largest BBS cohort described to date.

RESULTS

Of the 206 patients enrolled in the CRIBBS, 21 children (10.2 %; 16 girls, 5 boys; median age 8.4 years) had been diagnosed with ESRD. Renal transplantation was performed in 18 of these individuals between 1982 and 2015, including repeat transplantation in some cases, for a total of 22 kidneys. Overall graft survival was 81.6 % at 1 year post-transplantation, 75.7 % at 5 years, 59 % at 10 years, and 49.2 % at 25 years. Patient survival was 94.4 % at 1 year post-transplantation, 87.2 % at 8 years, and 79.3 % at 25 years.

CONCLUSIONS

At a median follow-up time of 97 months, relatively few complications of renal transplantation were reported in the patients of this study. However, body mass index was significantly elevated in transplanted individuals compared to non-transplanted individuals participating in CRIBBS at the most recent follow-up. Although the frequency of obesity and other manifestations of the metabolic syndrome warrant meticulous management in this high-risk population, favorable long-term outcomes suggest that renal transplantation is a viable option for patients with BBS and ESRD.

Anesthetic considerations for patients with Bardet-Biedl syndrome: a case series and review of the literature

BACKGROUND

Bardet-Biedl syndrome (BBS) is a rare genetic condition with manifestations that can impact anesthetic and perioperative care. There is a void of literature describing the perioperative anesthetic management in this complex patient population.

OBJECTIVES

The purpose of this retrospective series was to describe the perioperative care of patients diagnosed with BBS at a large academic tertiary referral center with experience in caring for these patients.

METHODS

All patients receiving anesthesia during the time between July 10, 1997 and Jan 1, 2015 were identified. Anesthetic and perioperative records were reviewed in detail for demographic, echocardiographic, preoperative, intraoperative, and postoperative data.

RESULTS

We identified 12 patients with BBS undergoing 40 anesthetics at our institution. The study identified a high risk for difficult airway with need for advanced airway techniques (67% of patient's ≥ 18 years of age required either awake fiberoptic or video laryngoscopy techniques), cardiac abnormalities, renal impairment, morbid obesity, and intellectual disability as the main syndrome manifestations of interest to the anesthesiologist. No patient had perioperative complications directly related to BBS; however, each underwent thorough perioperative evaluation with emphasis on the systemic comorbidities associated with the syndrome. This report illustrates that patients with BBS can safely undergo anesthesia, but a detailed and often multidisciplinary preoperative evaluation is prudent.

Rare Genetic Forms of Obesity: Clinical Approach and Current Treatments in 2016

Obesity results from a synergistic relationship between genes and the environment. The phenotypic expression of genetic factors involved in obesity is variable, allowing to distinguish several clinical pictures of obesity. Monogenic obesity is described as rare and severe early-onset obesity with abnormal feeding behavior and endocrine disorders. This is mainly due to autosomal recessive mutations in genes of the leptin-melanocortin pathway which plays a key role in the hypothalamic control of food intake. Melanocortin 4 receptor(MC4R)-linked obesity is characterized by the variable severity of obesity and no notable additional phenotypes. Mutations in the MC4R gene are involved in 2-3% of obese children and adults; the majority of these are heterozygous. Syndromic obesity is associated with mental retardation, dysmorphic features, and organ-specific developmental abnormalities. Additional genes participating in the development of hypothalamus and central nervous system have been regularly identified. But to date, not all involved genes have been identified so far. New diagnostic tools, such as whole-exome sequencing, will probably help to identify other genes. Managing these patients is challenging. Indeed, specific treatments are available only for specific types of monogenic obesity, such as leptin deficiency. Data on bariatric surgery are limited and controversial. New molecules acting on the leptin-melanocortin pathway are currently being developed.

Regulation of Insulin Receptor Trafficking by Bardet Biedl Syndrome Proteins

Insulin and its receptor are critical for the regulation of metabolic functions, but the mechanisms underlying insulin receptor (IR) trafficking to the plasma membrane are not well understood. Here, we show that Bardet Biedl Syndrome (BBS) proteins are necessary for IR localization to the cell surface. We demonstrate that the IR interacts physically with BBS proteins, and reducing the expression of BBS proteins perturbs IR expression in the cell surface. We show the consequence of disrupting BBS proteins for whole body insulin action and glucose metabolism using mice lacking different BBS genes. These findings demonstrate the importance of BBS proteins in underlying IR cell surface expression. Our data identify defects in trafficking and localization of the IR as a novel mechanism accounting for the insulin resistance commonly associated with human BBS. This is supported by the reduced surface expression of the IR in fibroblasts derived from patients bearing the M390R mutation in the BBS1 gene.

A main function of the hormone insulin in the body is to regulate metabolism of glucose. The hormone causes body cells in different organs and tissues to utilize glucose from the bloodstream, storing the excess amount. Insulin resistance which reflects the inability of insulin to properly regulate glucose metabolism is common in people with obesity and/or type 2 diabetes. This insulin resistance is strongly associated with cardiovascular disease and increases the risk of death. However, the reasons that account for this insulin resistance phenomenon are currently not well understood. Here, we show that Bardet Biedl Syndrome proteins are required for proper action of insulin. We found that cells or animals that are deficient in Bardet Biedl Syndrome proteins are unable to respond to insulin. These results provide an explanation why patients that carry mutations in the Bardet Biedl Syndrome genes are insulin resistant, and will potentially contribute to understand common human forms of insulin resistance.

Bariatric surgery in monogenic and syndromic forms of obesity

Currently, no topic is more controversial in bariatric surgery than performing these procedures on children with monogenic and syndromic forms of obesity. The medical community and the caregivers of those patients are struggling to find a solution that can alleviate their suffering and save their life. In all forms of obesity, dieting and physical activity do not result in significant weight loss and is associated with a high rate of weight regain. Additionally, effective medical therapy is not available yet. While there is significant debate about the risks and benefits of bariatric surgery in the adolescent population, there is an increasing number of studies that demonstrate the success of this option for the appropriate patients. Similarly, our experience demonstrated the same success not only in normal children and adolescents but also in those with monogenic and syndromic form of obesity.

Hyperphagia: current concepts and future directions proceedings of the 2nd international conference on hyperphagia

OBJECTIVE

Hyperphagia is a central feature of inherited disorders (e.g., Prader-Willi Syndrome) in which obesity is a primary phenotypic component. Hyperphagia may also contribute to obesity as observed in the general population, thus raising the potential importance of common underlying mechanisms and treatments. Substantial gaps in understanding the molecular basis of inherited hyperphagia syndromes are present as are a lack of mechanistic of mechanistic targets that can serve as a basis for pharmacologic and behavioral treatments.

DESIGN AND METHODS

International conference with 28 experts, including scientists and caregivers, providing presentations, panel discussions, and debates.

RESULTS

The reviewed collective research and clinical experience provides a critical body of new and novel information on hyperphagia at levels ranging from molecular to population. Gaps in understanding and tools needed for additional research were identified.

CONCLUSIONS

This report documents the full scope of important topics reviewed at a comprehensive international meeting devoted to the topic of hyperphagia and identifies key areas for future funding and research.

Hyperphagia among patients with Bardet-Biedl syndrome

BACKGROUND

The importance of hyperphagia as a cause for energy imbalance in humans with Bardet-Biedl syndrome (BBS) has not been established. We therefore compared hyperphagic symptoms in patients with BBS vs. controls.

METHODS

We studied 13 patients with BBS and 23 non-syndromic controls with similar age, sex and body mass index (BMI) z-score. A 13-item hyperphagia questionnaire was completed by patients' parents/guardians.

RESULTS

Total hyperphagia questionnaire score was higher in BBS than controls (27.6 ± 9.0 vs. 19.1 ± 7.9, P = 0.005). Behaviour and drive subscales were higher for BBS than controls (12.5 ± 4.1 vs. 7.8 ± 3.2, P = 0.001, and 11.2 ± 4.1 vs. 8.3 ± 3.8, P = 0.04, respectively); severity was not significantly different between groups (3.8 ± 1.5 vs. 3.0 ± 1.3, P = 0.072). After adjustment for demographic variables and BMI z-score, total and behaviour subscale scores remained significantly different between groups, suggesting food-seeking activity, rather than preoccupation with food may be the main hyperphagic feature among patients with BBS.

CONCLUSION

Appetite dysregulation may contribute to obesity in BBS.

Hypothalamic obesity in children

Hypothalamic obesity is an intractable form of obesity syndrome that was initially described in patients with hypothalamic tumours and surgical damage. However, this definition is now expanded to include obesity developing after a variety of insults, including intracranial infections, infiltrations, trauma, vascular problems and hydrocephalus, in addition to acquired or congenital functional defects in central energy homeostasis in children with the so-called common obesity. The pathogenetic mechanisms underlying hypothalamic obesity are complex and multifactorial. Weight gain results from damage to the ventromedial hypothalamus, which leads, variously, to hyperphagia, a low-resting metabolic rate; autonomic imbalance; growth hormone-, gonadotropins and thyroid-stimulating hormone deficiency; hypomobility; and insomnia. Hypothalamic obesity did not receive enough attention, as evidenced by rarity of studies in this group of patients. A satellite symposium was held during the European Congress of Obesity in May 2011, in Istanbul, Turkey, to discuss recent developments and concepts regarding pathophysiology and management of hypothalamic obesity in children. An international group of leading researchers presented certain aspects of the problem. This paper summarizes the highlights of this symposium. Understanding the central role of the hypothalamus in the regulation of feeding and energy metabolism will help us gain insights into the pathogenesis and management of common obesity.

Bariatric surgery in hypothalamic obesity

Craniopharyngiomas (CP) are epithelial neoplasms generally found in the area of the pituitary and hypothalamus. Despite benign histology, these tumors and/or their treatment often result in significant, debilitating disorders of endocrine, neurological, behavioral, and metabolic systems. Severe obesity is observed in a high percentage of patients with CP resulting in significant comorbidities and negatively impacting quality of life. Obesity occurs as a result of hypothalamic damage and disruption of normal homeostatic mechanisms regulating energy balance. Such pathological weight gain, termed hypothalamic obesity (HyOb), is often severe and refractory to therapy. Unfortunately, neither lifestyle intervention nor pharmacotherapy has proven effective in the treatment of HyOb. Given the limited choices and poor results of these treatments, several groups have examined bariatric surgery as a treatment alternative for patients with CP-HyOb. While a large body of evidence exists supporting the use of bariatric surgery in the treatment of exogenous obesity and its comorbidities, its role in the treatment of HyOb has yet to be defined. To date, the existing literature on bariatric surgery in CP-HyOb is largely limited to case reports and series with short term follow-up. Here we review the current reports on the use of bariatric surgery in the treatment of CP-HyOb. We also compare these results to those reported for other populations of HyOb, including Prader-Willi Syndrome, Bardet-Biedl syndrome, and hypothalamic melanocortin signaling defects. While initial reports of bariatric surgery in CP-HyOb are promising, their limited scope makes it difficult to draw any substantial conclusions as to the long term safety and efficacy of bariatric surgery in CP-HyOb. There continues to be a need for more robust, controlled, prospective studies with long term follow-up in order to better define the role of bariatric surgery in the treatment of HyOb.

Potential amelioration of morbidity in patients with chromosomal anomalies: relevance to Bardet-Biedl syndrome

Given the genetic basis of their disease, children with major chromosomal abnormalities including Bardet-Biedl syndrome (BBS) are generally considered to have a guarded prognosis with persistence or progression of disease manifestations. Although various therapeutic interventions are commonly used to control signs and symptoms of illness, parents of BBS children are usually cautioned against hoping for sustained improvement. A case of a 21-month-old girl, diagnosed with BBS, manifesting signs of worsening visual impairment, obesity, irascible and disordered behaviour, as well as developmental delay, is presented. After initial evaluation suggested specific biochemical deficiencies, nutritional status correction was undertaken and the patient's signs and symptoms subsequently resolved over the course of several months. To the authors' knowledge, this is the first case report of sustained resolution of all disease manifestations in the face of previously deteriorating health in a young child with this major chromosomal abnormality. It appears that biochemical imbalances and insufficiencies resulting from abnormal metabolism and excretion are potentially amenable to extraordinary dietary supplementation, with partial or complete resolution of clinical abnormalities. It is recommended that all children with chromosomal abnormalities have biochemical and nutritional status evaluation with correction of disordered biochemistry as is possible.

Effectiveness and cost-effectiveness of paediatric bariatric surgery: a systematic review

Strong evidence for successful and cost-effective obesity management strategies is still generally lacking, leading the medical profession to rely increasingly on surgical options to treat obesity in children and adolescents. We performed a systematic review to examine the effectiveness of surgical interventions to treat obese children and adolescents, and whether they are cost-effective. We searched PubMed, ISI Web of Science, Embase and the Cochrane Library to 6 September 2010, and hand-searched bibliographies. We included articles with English abstracts if they examined subjects ≤19 years of age, reported at least one postoperative weight loss measure and at least 1 year of postoperative follow-up. Thirty-seven relevant papers on bariatric surgery effectiveness in 831 children or adolescents were included, spanning 36 years. Thirteen studies examined gastric banding, with mean body mass index (BMI) reductions ranging from 8.5 to 43 kg m(-2) . Weight gain was reported in one case study. Eight papers examined Roux-en-Y gastric bypass, with mean BMI reductions ranging from 9 to 25 kg m(-2) . Fourteen publications studied other forms of bariatric surgery: sleeve gastrectomies, vertical banded gastroplasty, biliopancreatic diversion or a combination of procedures. Mean BMI reductions ranged from 9 to 24 kg m(-2) . Three surgery-related mortalities were reported, as was weight regain in several cases. The majority of studies reported resolution or improvement of comorbid conditions. A range of postoperative complications were identified across surgery types, including: ulcers, intestinal leakage, wound infection, anastomotic stricture, nutritional deficiencies, bowel obstruction, pulmonary embolism, disrupted staple lines, band slippage, psychological intolerance and repeated vomiting. Evidence on cost-effectiveness was limited to one Australian modelling project, which deemed laparoscopic adjustable gastric banding cost-effective for adolescents. Existing evidence - although based generally on underpowered, retrospective studies - suggests that bariatric surgery in older children results in significant weight loss and improvements in comorbidities and quality of life. However, postoperative complications, compliance and follow-up may be more problematic in adolescents than adults, and availability of long-term data on safety, effectiveness and cost-effectiveness remains largely unknown. Pending an improvement in the quality of available evidence, a cautious approach to child and adolescent bariatric surgery is warranted, and reversible techniques are advisable compared to approaches that permanently alter anatomy.