Comprehensive Endocrine-Metabolic Evaluation of Patients With Alström Syndrome Compared With BMI-Matched Controls

Diseases of the primary cilia: a clinical characteristics review

Ciliopathies encompass a broad spectrum of diseases stemming from dysfunction of the primary (non-motile) cilia, present on almost all cells in the human body. These disorders include autosomal dominant and recessive polycystic kidney diseases, nephronophthisis, and multisystem ciliopathies such as Joubert, Meckel, Bardet-Biedl, Alström, oral-facial-digital syndromes, and skeletal ciliopathies. The majority of these ciliopathies are associated with fibrocystic kidney disease resulting in progressive kidney dysfunction. In addition, many ciliopathies are associated with extra-renal manifestations including congenital hepatic fibrosis, retinal dystrophy, obesity, and brain and skeletal anomalies. The diagnoses may be challenging due to their overlapping clinical features and molecular heterogeneity. To date, over 190 genes encoding proteins that localize to the primary cilia have been identified as disease-causing. This review will discuss the clinical features of the most frequently encountered disorders of primary cilia.

Alström syndrome-wide clinical variability within the same variant: a case report and literature review

Background

Alström disease is a rare disorder caused by various variants in the ALMS1 gene. It is characterised by multiorgan involvement, namely neurosensory deficits, endocrine and metabolic disturbances, cardiomyopathy, and hepatic and renal dysfunction. The disease exhibits marked interindividual variability, both in clinical manifestations and age of onset. Several attempts have been made to establish a relationship between phenotype and genotype, with little success.

Methods

We present the case of an infant who presented with dilated cardiomyopathy, above-average weight and neurosensory deficits, raising the suspicion for Alström syndrome, later confirmed through genetic testing. Moreover, we conducted an extensive literature search to identify all reported cases having the same variant as our patient, in order to evaluate whether specific mutated alleles have a role in determining phenotype-genotype associations.

Results

A 4-month-old female infant with a recent history of bronchiolitis was referred to our centre due to a systolic murmur. In our service, the clinical exam was significant for above-average weight, dyspnea, wheezing and a grade II systolic murmur. Echocardiography revealed dilated cardiomyopathy with severe systolic dysfunction of the left ventricle. Laboratory investigations revealed elevated NT-proBNP and troponin levels, along with positive IgM antibodies for CMV and EBV. Dilated cardiomyopathy attributed to viral myocarditis was suspected. Treatment with ACE inhibitors and diuretics was started, with a favourable response initially. However, after a few months, the patient presented with vertical nystagmus and head bobbing. The ophthalmologic exam revealed cone-rode dystrophy. Considering the constellation of symptoms, Alström syndrome was suspected. Genetic testing revealed a homozygous variant [c.4156dup (p.Thr1386Asnfs*15)] in the ALMS1 gene, confirming the diagnosis.

Conclusion

Our literature review revealed 8 additional cases harbouring the same variant as our patient, five in a heterozygous state, two in a homozygous state and one with only one allele identified. The identified patients presented high heterogeneity of clinical manifestations and age of onset. The heterogeneity persisted even in patients with homozygous variants, suggesting the involvement of factors beyond the specific disease-causing variant in determining disease manifestation. Therefore, genotype-phenotype correlations might not be supported by specific variants.

Differentiating monogenic and syndromic obesities from polygenic obesity: Assessment, diagnosis, and management

Background

Obesity is a multifactorial neurohormonal disease that results from dysfunction within energy regulation pathways and is associated with increased morbidity, mortality, and reduced quality of life. The most common form is polygenic obesity, which results from interactions between multiple gene variants and environmental factors. Highly penetrant monogenic and syndromic obesities result from rare genetic variants with minimal environmental influence and can be differentiated from polygenic obesity depending on key symptoms, including hyperphagia; early-onset, severe obesity; and suboptimal responses to nontargeted therapies. Timely diagnosis of monogenic or syndromic obesity is critical to inform management strategies and reduce disease burden. We outline the physiology of weight regulation, role of genetics in obesity, and differentiating characteristics between polygenic and rare genetic obesity to facilitate diagnosis and transition toward targeted therapies.

Methods

In this narrative review, we focused on case reports, case studies, and natural history studies of patients with monogenic and syndromic obesities and clinical trials examining the efficacy, safety, and quality of life impact of nontargeted and targeted therapies in these populations. We also provide comprehensive algorithms for diagnosis of patients with suspected rare genetic causes of obesity.

Results

Patients with monogenic and syndromic obesities commonly present with hyperphagia (ie, pathologic, insatiable hunger) and early-onset, severe obesity, and the presence of hallmark characteristics can inform genetic testing and diagnostic approach. Following diagnosis, specialized care teams can address complex symptoms, and hyperphagia is managed behaviorally. Various pharmacotherapies show promise in these patient populations, including setmelanotide and glucagon-like peptide-1 receptor agonists.

Conclusion

Understanding the pathophysiology and differentiating characteristics of monogenic and syndromic obesities can facilitate diagnosis and management and has led to development of targeted pharmacotherapies with demonstrated efficacy for reducing body weight and hunger in the affected populations.

Defining the cardiovascular phenotype of adults with Alström syndrome

BACKGROUND

>40% of infants with Alström Syndrome (AS) present with a transient, severe cardiomyopathy in the first months of life, with apparent recovery in survivors. One in five individuals then develop a later-onset cardiomyopathy but wide clinical variability is observed, even within the same family. The rationale for this study is to provide a comprehensive evaluation of the cardiovascular phenotype in adults with AS.

METHODS

Adults attending the National Centre for AS in England were studied. All patients underwent biochemical, 12- lead electrocardiography, echocardiography, and cardiovascular magnetic resonance imaging.

RESULTS

47 adults with AS (64% male; mean age 33 years; 66% white British) were studied. Seven (15%) survived infantile cardiomyopathy and 23 (49%) developed adult-onset cardiomyopathy. Conventional risk factors for cardiovascular disease were present in 39 (83%). Abnormalities were present on biomarkers in 16 (34%), ECG 30 (64%), echocardiography 19 (40%) and CMR 31 (66%). Coronary artery imaging was performed in six (13%), with abnormalities in two. Cardiac, renal, and liver markers were more often impaired in older patients, with impaired left ventricular ejection fraction, reduced global longitudinal strain and late enhancement. 6 (13%) had severe pulmonary hypertension (mean pulmonary artery pressure 46 mmHg) due to left heart disease on invasive testing.

CONCLUSION

Cardiomyopathy is common in adults with AS, complicated in a significant proportion by atherosclerotic coronary artery disease and restrictive cardiomyopathy, confirmed on CMR and invasive testing. With advancing age, cardiovascular complications are compounded by contemporaneous renal and liver disease.

Emerging mechanistic understanding of cilia function in cellular signalling

Primary cilia are solitary, immotile sensory organelles present on most cells in the body that participate broadly in human health, physiology and disease. Cilia generate a unique environment for signal transduction with tight control of protein, lipid and second messenger concentrations within a relatively small compartment, enabling reception, transmission and integration of biological information. In this Review, we discuss how cilia function as signalling hubs in cell-cell communication using three signalling pathways as examples: ciliary G-protein-coupled receptors (GPCRs), the Hedgehog (Hh) pathway and polycystin ion channels. We review how defects in these ciliary signalling pathways lead to a heterogeneous group of conditions known as 'ciliopathies', including metabolic syndromes, birth defects and polycystic kidney disease. Emerging understanding of these pathways' transduction mechanisms reveals common themes between these cilia-based signalling pathways that may apply to other pathways as well. These mechanistic insights reveal how cilia orchestrate normal and pathophysiological signalling outputs broadly throughout human biology.

Mesenchymal-specific Alms1 knockout in mice recapitulates metabolic features of Alström syndrome

OBJECTIVE

Alström Syndrome (AS), caused by biallelic ALMS1 mutations, includes obesity with disproportionately severe insulin resistant diabetes, dyslipidemia, and fatty liver. Prior studies suggest that hyperphagia is accounted for by loss of ALMS1 function in hypothalamic neurones, whereas disproportionate metabolic complications may be due to impaired adipose tissue expandability. We tested this by comparing the metabolic effects of global and mesenchymal stem cell (MSC)-specific Alms1 knockout.

METHODS

Global Alms1 knockout (KO) mice were generated by crossing floxed Alms1 and CAG-Cre mice. A Pdgfrα-Cre driver was used to abrogate Alms1 function selectively in MSCs and their descendants, including preadipocytes. We combined metabolic phenotyping of global and Pdgfrα+ Alms1-KO mice on a 45% fat diet with measurements of body composition and food intake, and histological analysis of metabolic tissues.

RESULTS

Assessed on 45% fat diet to promote adipose expansion, global Alms1 KO caused hyperphagia, obesity, insulin resistance, dyslipidaemia, and fatty liver. Pdgfrα-cre driven KO of Alms1 (MSC KO) recapitulated insulin resistance, fatty liver, and dyslipidaemia in both sexes. Other phenotypes were sexually dimorphic: increased fat mass was only present in female Alms1 MSC KO mice. Hyperphagia was not evident in male Alms1 MSC KO mice, but was found in MSC KO females, despite no neuronal Pdgfrα expression.

CONCLUSIONS

Mesenchymal deletion of Alms1 recapitulates metabolic features of AS, including fatty liver. This confirms a key role for Alms1 in the adipose lineage, where its loss is sufficient to cause systemic metabolic effects and damage to remote organs. Hyperphagia in females may depend on Alms1 deficiency in oligodendrocyte precursor cells rather than neurones. AS should be regarded as a forme fruste of lipodystrophy.

New variants of ALMS1 gene and familial Alström syndrome case series

OBJECTIVES

To report two new variants of ALMS1 gene and to discuss the audiological evolution and clinical phenotype in two pairs of siblings with Alström syndrome.

REPORT

This paper is a multi-disciplinary diagnostic evaluation, with genetic and audiological analysis that aims to report two new variants of the ALMS1 gene and to discuss the audiological evolution and clinical phenotype in a case series of patients with familial Alström syndrome. Therefore, we describe 4 cases presenting a complete audiometric profile of two pairs of unrelated siblings, to provide a better understanding of this very rare disease. Additionally, the present study identified two heterozygous mutations in the ALMS1 gene.

CONCLUSION

This Clinical Capsule Report highlights the importance of audiological monitoring throughout the development of patients with Alström syndrome. The two variants found were not previously reported in the literature, which expands the spectrum of ALMS1 variants in Alström syndrome.

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.

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.

Energy expenditure deficits drive obesity in a mouse model of Alström syndrome

OBJECTIVE

Alström syndrome (AS) is a rare multisystem disorder of which early onset childhood obesity is a cardinal feature. Like humans with AS, animal models with Alms1 loss-of-function mutations develop obesity, supporting the notion that ALMS1 is required for the regulatory control of energy balance across species. This study aimed to determine which component(s) of energy balance are reliant on ALMS1.

METHODS

Comprehensive energy balance phenotyping was performed on Alms1tvrm102 mice at both 8 and 18 weeks of age.

RESULTS

It was found that adiposity gains occurred early and rapidly in Alms1tvrm102 male mice but much later in females. Rapid increases in body fat in males were due to a marked reduction in energy expenditure (EE) during early life and not due to any genotype-specific increases in energy intake under chow conditions. Energy intake did increase in a genotype-specific manner when mice were provided a high-fat diet, exacerbating the effects of reduced EE on obesity progression. The EE deficit observed in male Alms1tvrm102 mice did not persist as mice aged.

CONCLUSIONS

Either loss of ALMS1 causes a developmental delay in the mechanisms controlling early life EE or activation of compensatory mechanisms occurs after obesity is established in AS. Future studies will determine how ALMS1 modulates EE and how sex moderates this process.

Mesenchymal-specific Alms1 knockout in mice recapitulates key metabolic features of Alström Syndrome

Background

Alström Syndrome (AS), a multi-system disease caused by mutations in the ALMS1 gene, includes obesity with disproportionately severe insulin resistant diabetes, dyslipidemia, and hepatosteatosis. How loss of ALMS1 causes this phenotype is poorly understood, but prior studies have circumstancially implicated impaired adipose tissue expandability. We set out to test this by comparing the metabolic effects of selective Alms1 knockout in mesenchymal cells including preadipocytes to those of global Alms1 knockout.

Methods

Global Alms1 knockout (KO) mice were generated by crossing floxed Alms1 and CAG-Cre mice. A Pdgfrα -Cre driver was used to abrogate Alms1 function selectively in mesenchymal stem cells (MSCs) and their descendants, including preadipocytes. We combined metabolic phenotyping of global and Pdgfrα + Alms1 -KO mice on a 45% fat diet with measurements of body composition and food intake, and histological analysis of metabolic tissues.

Results

Global Alms1 KO caused hyperphagia, obesity, insulin resistance, dyslipidaemia, and fatty liver. Pdgfrα - cre driven KO of Alms1 (MSC KO) recapitulated insulin resistance, fatty liver, and dyslipidaemia in both sexes. Other phenotypes were sexually dimorphic: increased fat mass was only present in female Alms1 MSC KO mice. Hyperphagia was not evident in male Alms1 MSC KO mice, but was found in MSC KO females, despite no neuronal Pdgfr α expression.

Conclusions

Mesenchymal deletion of Alms1 recapitulates the metabolic features of AS, including severe fatty liver. This confirms a key role for Alms1 in the adipose lineage, where its loss is sufficient to cause systemic metabolic effects and damage to remote organs. AS should be regarded as a forme fruste of lipodystrophy. Therapies should prioritise targeting positive energy balance.

Ciliopathies in pediatric endocrinology

Ciliopathies are a group of disorders that involve many organs and systems. In this review, we consider the role of the cilium in multiorgan pathology with a focus on endocrinological aspects. Identification of new genes and mutations is the major challenge in development of a tailored and appropriate therapy. It is expected that new mutations will be identified to characterize ciliopathies and promote new therapies.

Supportive care in a patient with Alstrom syndrome with hyperphenylalaninemia and sleep problems

Alstrom syndrome is a rare genetic disorder with an autosomal recessive mutation in the ALMS1 gene. The disease's manifestations include ophthalmic problems, hearing loss, obesity, and cardiovascular disorders. In addition, medical cases include other organ complications. However, the overlapping variety of such symptoms with other diseases may delay the diagnosis. In this article, we describe the case of a 7-year-old female patient with Alstrom syndrome, and cardiovascular and hyperphenylalaninemia diseases since birth. Other symptoms included diabetes and ophthalmologic problems with skeletal disability. Blindness and hearing impairment were diagnosed, along with recurrence of respiratory problems at the age of 7 years. The patient's obesity-induced snoring predisposed her to uncontrolled blood glucose. In fact, respiratory tract problems and sleep disorders had occurred as a degraded cycle and left her with a severe disability for years. The similarity of the symptoms with other diseases had misled the physician in diagnosis. However, a polysomnography test (because of complaints of short sleep duration) recognized the source of the patient's sleep disorders and breathing problems. Eventually, we delivered a portable ventilator to the child for continuous positive airway pressure (CPAP) therapy. The child's breathing and oxygenation conditions improved. Using the ventilator and the CPAP system, we discharged her from the hospital without requiring oxygenation, in a stable condition. The procedure could prevent the patient from hypoxia and retinal problem.

Hematopoietic Stem Cells and Metabolic Deterioration in Alström Syndrome, a Rare Genetic Model of the Metabolic Syndrome

Alström syndrome (AS) is a rare genetic disease caused by ALMS1 mutations, characterized by short stature, and vision and hearing loss. Patients with AS develop the metabolic syndrome, long-term organ complications, and die prematurely. We explored the association between AS and a shortage of hematopoietic stem/progenitor cells (HSPCs), which is linked to metabolic diseases and predicts diabetic complications. We included patients with AS at a national referral center. We measured HSPCs with flow cytometry at baseline and follow-up. We followed patients up to January 2022 for metabolic worsening and end-organ damage. We evaluated HSPC levels and mobilization as well as bone marrow histology in a murine model of AS. In 23 patients with AS, we found significantly lower circulating HSPCs than in healthy blood donors (-40%; P = .002) and age/sex-matched patients (-25%; P = .022). Longitudinally, HSPCs significantly declined by a further 20% in patients with AS over a median of 36 months (interquartile range 30-44). Patients with AS who displayed metabolic deterioration over 5.3 years had lower levels of HSPCs, both at baseline and at last observation, than those who did not deteriorate. Alms1-mutated mice were obese and insulin resistant and displayed significantly reduced circulating HSPCs, despite no overt hematological abnormality. Contrary to what was observed in diabetic mice, HSPC mobilization and bone marrow structure were unaffected. We found depletion of HSPCs in patients with AS, which was recapitulated in Alms1-mutated mice. Larger and longer studies will be needed to establish HSPCs shortage as a driver of metabolic deterioration leading to end-organ damage in AS.

Ciliary control of adipocyte progenitor cell fate regulates energy storage

The primary cilium is a cellular sensory organelle found in most cells in our body. This includes adipocyte progenitor cells in our adipose tissue, a complex organ involved in energy storage, endocrine signaling, and thermogenesis. Numerous studies have shown that the primary cilium plays a critical role in directing the cell fate of adipocyte progenitor cells in multiple adipose tissue types. Accordingly, diseases with dysfunctional cilia called ciliopathies have a broad range of clinical manifestations, including obesity and diabetes. This review summarizes our current understanding of how the primary cilium regulates adipocyte progenitor cell fate in multiple contexts and illustrates the importance of the primary cilium in regulating energy storage and adipose tissue function.

Identification of bone metabolism disorders in patients with Alström and Bardet-Biedl syndromes based on markers of bone turnover and mandibular atrophy

Objectives

Causative variants in genes responsible for Alström syndrome (ALMS) and Bardet-Biedl syndrome (BBS) cause damage to primary cilia associated with correct functioning of cell signaling pathways in many tissues. Despite differences in genetic background, both syndromes affect multiple organs and numerous clinical manifestations are common including obesity, retinal degeneration, insulin resistance, type 2 diabetes and many others. The aim of the study was to evaluate bone metabolism abnormalities and their relation to metabolic disorders based on bone turnover markers and presence of mandibular atrophy in patients with ALMS and BBS syndromes.

Material and methods

In 18 patients (11 with ALMS and 7 with BBS aged 5–29) and in 42 age-matched (p < 0.05) healthy subjects, the following markers of bone turnover were assessed: serum osteocalcin (OC), osteoprotegerin (OPG), s-RANKL and urinary deoxypyridinoline - DPD. In addition, a severity of alveolar atrophy using dental panoramic radiograms was evaluated.

Results

Lower serum OC (p = 0.0004) and urinary DPD levels (p = 0.0056) were observed in the study group compared to controls. In ALMS and BBS patients, serum OC and urinary DPD values negatively correlated with the HOMA-IR index, while a positive correlation between the OC and 25-OHD levels and a negative correlation between s-RANKL and fasting glucose concentrations were found. A significant difference in the incidence of low-grade mandibular atrophy between patients with ALMS and BBS and controls (p < 0.0001) was observed.

Conclusions

The identification of bone metabolism disorders in patients with ALMS and BBS syndromes indicates the necessity to provide them with appropriate diagnosis and treatment of these abnormalities.

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Bone metabolism disorders in Alstrom and Bardet-Biedl syndromes

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Markers of bone turnover in Alstrom and Bardet-Biedl syndromes

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Mandibular atrophy in Alstrom and Bardet-Biedl syndromes

Islet cilia and glucose homeostasis

Diabetes is a growing pandemic affecting over ten percent of the U.S. population. Individuals with all types of diabetes exhibit glucose dysregulation due to altered function and coordination of pancreatic islets. Within the critical intercellular space in pancreatic islets, the primary cilium emerges as an important physical structure mediating cell-cell crosstalk and signal transduction. Many events leading to hormone secretion, including GPCR and second-messenger signaling, are spatiotemporally regulated at the level of the cilium. In this review, we summarize current knowledge of cilia action in islet hormone regulation and glucose homeostasis, focusing on newly implicated ciliary pathways that regulate insulin exocytosis and intercellular communication. We present evidence of key signaling proteins on islet cilia and discuss ways in which cilia might functionally connect islet endocrine cells with the non-endocrine compartments. These discussions aim to stimulate conversations regarding the extent of cilia-controlled glucose homeostasis in health and in metabolic diseases.

Case Report:Pregnancy and birth in a mild phenotype of Alström syndrome

Background: Alström syndrome (AS) is an ultrarare multisystemic progressive disease caused by autosomal recessive variations of the ALMS1 gene (2p13). AS is characterized by double sensory impairment, cardiomyopathy, childhood obesity, extreme insulin resistance, early nonalcoholic fatty liver disease, renal dysfunction, respiratory disease, endocrine and urologic disorders. In female AS patients, hyperandrogenism has been described but fertility issues and conception have not been investigated so far.

Case: This case report describes the spontaneous conception, pregnancy, and birth in a 27-year-old woman with AS, characterized by a mild phenotype with late onset of visual impairment, residual perception of light, and hypertension. Before pregnancy, menses were regular with increased levels of dihydrotestosterone and androstanediol glucuronide in the follicular phase, and the ovaries and endometrium were normal during vaginal ultrasound. A thorough clinical follow-up of the maternal and fetal conditions was carried out. A weight gain of 10 kg during pregnancy was recorded, and serial blood and urine tests were all within the normal range, except for mild anemia. The course of pregnancy was uneventful up to 34 weeks of gestation when preeclampsia developed with an abnormally high level of blood pressure and edema in the lower limbs. At 35 weeks + 3 days of gestation, an urgent cesarean section was performed, and a healthy male weighing 1,950 g was born. Histological examination of the placenta showed partial signs of flow obstruction, limited abruption areas, congested fetal vessels and villi, and a small single infarcted area.

Conclusion: The present case demonstrates for the first time that conceiving is possible for patients with ALMS. Particular attention should be given to the management of AS systemic comorbidities through the course of pregnancy.

Hypogonadism in Males With Genetic Neurodevelopmental Syndromes

Genetic syndromes that affect the nervous system may also disrupt testicular function, and the mechanisms for these effects may be interrelated. Most often neurological signs and symptoms predominate and hypogonadism remains undetected and untreated, while in other cases, a thorough evaluation of a hypogonadal male reveals previously unrecognized ataxia, movement disorder, muscle weakness, tremor, or seizures, leading to a syndromic diagnosis. Androgen deficiency in patients with neurological diseases may aggravate muscle weakness and fatigue and predispose patients to osteoporosis and obesity. The purpose of this mini review is to provide a current understanding of the clinical, biochemical, histologic, and genetic features of syndromes in which male hypogonadism and neurological dysfunction may coexist and may be encountered by the clinical endocrinologist.

Resting Energy Expenditure and Body Composition in Children and Adolescents With Genetic, Hypothalamic, Medication-Induced or Multifactorial Severe Obesity

Background

Pediatric obesity is a multifactorial disease which can be caused by underlying medical disorders arising from disruptions in the hypothalamic leptin-melanocortin pathway, which regulates satiety and energy expenditure.

Aim

To investigate and compare resting energy expenditure (REE) and body composition characteristics of children and adolescents with severe obesity with or without underlying medical causes.

Methods

This prospective observational study included pediatric patients who underwent an extensive diagnostic workup in our academic centre that evaluated endocrine, non-syndromic and syndromic genetic, hypothalamic, and medication-induced causes of obesity. REE was assessed by indirect calorimetry; body composition by air displacement plethysmography. The ratio between measured REE (mREE) and predicted REE (Schofield equations), REE%, was calculated, with decreased mREE defined as REE% ≤90% and elevated mREE ≥110%. Additionally, the influence of fat-free-mass (FFM) on mREE was evaluated using multiple linear regression.

Results

We included 292 patients (146 [50%] with body composition measurements), of which 218 (75%) patients had multifactorial obesity and 74 (25%) an underlying medical cause: non-syndromic and syndromic genetic (n= 29 and 28, respectively), hypothalamic (n= 10), and medication-induced (n= 7) obesity. Mean age was 10.8 ± 4.3 years, 59% were female, mean BMI SDS was 3.8 ± 1.1, indicating severe obesity. Mean REE% was higher in children with non-syndromic genetic obesity (107.4% ± 12.7) and lower in children with hypothalamic obesity (87.6% ± 14.2) compared to multifactorial obesity (100.5% ± 12.6, both p<0.01). In 9 children with pseudohypoparathyroidism type 1a, mean REE% was similar (100.4 ± 5.1). Across all patients, mREE was decreased in 60 (21%) patients and elevated in 69 (24%) patients. After adjustment for FFM, mREE did not differ between patients within each of the subgroups of underlying medical causes compared to multifactorial obesity (all p>0.05).

Conclusions

In this cohort of children with severe obesity due to various etiologies, large inter-individual differences in mREE were found. Consistent with previous studies, almost half of patients had decreased or elevated mREE. This knowledge is important for patient-tailored treatment, e.g. personalized dietary and physical activity interventions and consideration of pharmacotherapy affecting central energy expenditure regulation in children with decreased mREE.

Measuring hyperphagia in patients with monogenic and syndromic obesity

BACKGROUND

Hyperphagia is a key symptom in patients with monogenic obesity, but the assessment is challenging.

OBJECTIVES

We aimed to investigate the applicability of Dykens' Hyperphagia Questionnaire in patients with monogenic and syndromic obesity to assess the quality and severity of hyperphagia, and to compare our results with those reported in the literature.

METHODS

Patients with biallelic leptin receptor variants (LEPR, n = 8), heterozygous melanocortin-4 receptor variants (MC4R, n = 7) and 16p11.2 deletions, leading to a deletion of the Src homology 2B adaptor protein gene (n = 5) were included in the study. Hyperphagia was assessed by the parent-based, 13-item hyperphagia questionnaire from Dykens et al. (2007). A literature research was performed to identify published hyperphagia scores assessed by Dykens' Hyperphagia Questionnaire.

RESULTS

The total hyperphagia scores were similar in patients with biallelic LEPR and monoallelic MC4R variants (32.0 ± 9.3 vs. 31.4 ± 5.4), but significantly lower in patients with 16p11.2 deletions (21.4 ± 5.5, p < 0.05). Compared to patients with syndromic obesity (27.6 ± 9.0) from the literature, patients with LEPR and MC4R variants had higher total hyperphagia scores. Total hyperphagia scores in patients with 16p11.2 deletions were lower than for patients with other syndromic obesity forms (21.4 ± 5.5 vs. 24.6 ± 8.1), but similar to those for individuals with obesity without a genetic cause (22.9 ± 7.2).

CONCLUSIONS

Dykens' Hyperphagia Questionnaire seems to be a useful tool to assess hyperphagic behaviour in patients with monogenic and syndromic obesity.

Hearing Loss in Adults With Alström Syndrome-Experience From the UK National Alström Service

OBJECTIVE

To characterize the patterns of hearing loss and methods of hearing rehabilitation in the UK national cohort of adults with Alström syndrome.

STUDY DESIGN

Retrospective review of electronic patient records.

SETTING

UK National multi-disciplinary team (MDT) Alström service held at the Queen Elizabeth Hospital, Birmingham.

PATIENTS

Forty one adult patients with a diagnosis of Alström syndrome, confirmed via ALMS1 gene sequencing, are under ongoing review within the UK National MDT Alström service.

MAIN OUTCOME MEASURES

Magnitude and type of hearing loss were analyzed using patients' audiometric data. Deterioration of hearing was calculated using serial pure tone audiograms. Methods of hearing rehabilitation used by patients and potential candidacy for cochlear implantation were analyzed.

RESULTS

Of 34 patients with available audiograms, all had sensorineural hearing loss (SNHL). Dual sensory (visual and hearing) loss was present in 32/34 (94%) patients. Hearing deteriorated with advancing age, at 1.23 dB/yr. Severe- profound SNHL was present in 9/34 (26%) cases. Air conduction hearing aids were used in 27/34 (79%) cases, and cochlear implants in 2/34 (5%).

CONCLUSIONS

Alström syndrome is an ultra-rare genetic disorder with progressive, debilitating multi-system manifestations, including SNHL. The UK National MDT Alström service represents one of the largest reported adult cohorts in the world. SNHL in this group was ubiquitous, showing a rapid decline in hearing with age. Annual audiometric assessment to enable early diagnosis of hearing loss and optimum rehabilitation are paramount to minimize the impact of hearing loss in this condition.

The Interaction of Obesity and Reproductive Function in Adolescents

Obesity is increasing worldwide, including in pediatrics. Adequate nutrition is required for initiation of menses, and there is a clear secular trend toward earlier pubertal onset and menarche in females in countries around the globe. Similar findings of earlier pubertal start are suggested in males. However, as individuals and populations have crossed into over-nutritional states including overweight and obesity, the effect of excess weight on disrupting reproductive function has become apparent. Hypothalamic hypogonadism and polycystic ovary syndrome are two conditions where reproductive function appears to directly relate to excess weight. Clinical findings in individuals with certain polygenic and monogenic obesity syndromes, which also have reproductive disruptions, have helped elucidate neurologic pathways that are common to both. Clinical endocrinopathies such as hypothyroidism or panhypopituitarism also aide in the understanding of the role of the endocrine system in weight gain. Understanding the intersection of obesity and reproductive function may lead to future therapies which can treat both conditions.

Causative Mechanisms of Childhood and Adolescent Obesity Leading to Adult Cardiometabolic Disease: A Literature Review

The past few decades have shown a worrisome increase in the prevalence of obesity and its related illnesses. This increasing burden has a noteworthy impact on overall worldwide mortality and morbidity, with significant economic implications as well. The same trend is apparent regarding pediatric obesity. This is a particularly concerning aspect when considering the well-established link between cardiovascular disease and obesity, and the fact that childhood obesity frequently leads to adult obesity. Moreover, most obese adults have a history of excess weight starting in childhood. In addition, given the cumulative character of both time and severity of exposure to obesity as a risk factor for associated diseases, the repercussions of obesity prevalence and related morbidity could be exponential in time. The purpose of this review is to outline key aspects regarding the current knowledge on childhood and adolescent obesity as a cardiometabolic risk factor, as well as the most common etiological pathways involved in the development of weight excess and associated cardiovascular and metabolic diseases.

Primary Cilia Are Critical Regulators of White Adipose Tissue Expansion

The primary cilium is a microtubule-based cellular protrusion found on most mammalian cell types in diverse tissues. It functions as a cellular antenna to sense and transduce a broad range of signals, including odorants, light, mechanical stimuli, and chemical ligands. This diversity in signals requires cilia to display a context and cell type-specific repertoire of receptors. Recently, primary cilia have emerged as critical regulators of metabolism. The importance of primary cilia in metabolic disease is highlighted by the clinical features of human genetic disorders with dysfunctional ciliary signaling, which include obesity and diabetes. This review summarizes the current literature on the role of primary cilia in metabolic disease, focusing on the importance of primary cilia in directing white adipose tissue expansion during obesity.

A review of Alström syndrome: a rare monogenic ciliopathy

Alström syndrome is a rare monogenic ciliopathy caused by a mutation to the Alström syndrome 1 (ALMS1) gene. Alström syndrome has an autosomal recessive nature of inheritance. Approximately 1,200 cases of Alström syndrome have been identified worldwide. Complications of the disease are likely caused by dysfunctional cilia with complications arising early in life. The known complications of Alström syndrome have been reported to impact multiple major organ systems, including the endocrine system, cardiac system, renal system, sensory system, and hepatic system. The symptoms of Alström syndrome have great variability in presentation and intensity but often lead to organ damage. This has resulted in a shortened lifespan for individuals affected by Alström syndrome. Individuals with the disease rare exceed the age of 50. Currently, there are no specific treatments for Alström syndrome that can cure the disease, prevent the complications, or reverse the complications. Current management involves management of symptoms with the goal of improving quality of life and lifespan. This review aims to summarize the current knowledge on the epidemiology, diagnosis, pathophysiology, complications, management, and prognosis of Alström syndrome. In addition to that, this review also aims to raise awareness and encourage research on Alström syndrome as the condition has a huge impact on affected individuals.

The efficacy and safety of setmelanotide in individuals with Bardet-Biedl syndrome or Alström syndrome: Phase 3 trial design

Background

A phase 2 trial has suggested that treatment with the melanocortin-4 receptor (MC4R) agonist setmelanotide is associated with a decrease in hunger and weight-related outcomes in participants with Bardet-Biedl syndrome (BBS) and Alström syndrome. Here, we present the study design of an ongoing, randomized, double-blind, placebo-controlled, phase 3 trial to assess the long-term efficacy and safety of setmelanotide for the treatment of obesity and hyperphagia in individuals with BBS or Alström syndrome (ClinicalTrials.gov identifier: NCT03746522).

Methods

It was initially planned that ~30 participants aged ≥6 years with a clinical diagnosis of BBS or Alström syndrome would be enrolled. Participants with obesity as defined by a body mass index ≥30 kg/m² (in those aged ≥16 years) or a weight >97th percentile (in those aged 6–15 years) are included. Participants are initially randomized in a 1:1 ratio to receive setmelanotide or placebo for 14 weeks (period 1). Following period 1, all participants receive 38 weeks of open-label treatment with setmelanotide (period 2). In each treatment period, setmelanotide is administered at 3 mg once a day following completion of dose escalation. The primary endpoint is the proportion of participants aged ≥12 years achieving a clinically meaningful reduction from baseline (≥10%) in body weight after ~52 weeks (eg, following period 2). Safety and tolerability are assessed by frequency of adverse events.

Conclusions

This pivotal trial is designed to evaluate the efficacy and safety of setmelanotide for the treatment of obesity and hyperphagia in individuals with BBS and Alström syndrome.

Submission category

Study Design, Statistical Design, Study Protocols.

Alström syndrome: an ultra-rare monogenic disorder as a model for insulin resistance, type 2 diabetes mellitus and obesity

BACKGROUND

Alström syndrome (ALMS) is a monogenic ultra-rare disorder with a prevalence of one per million inhabitants caused by pathogenic variants of ALMS1 gene. ALMS1 is located on chromosome 2p13, spans 23 exons and encodes a predicted 461.2-kDa protein of 4169 amino acids. The infantile cone-rod dystrophy with nystagmus and severe visual impairment is the earliest and most consistent clinical manifestation of ALMS. In addition, infantile transient cardiomyopathy, early childhood obesity with hyperphagia, deafness, insulin resistance (IR), type 2 diabetes mellitus (T2DM), systemic fibrosis and progressive renal or liver dysfunction are common findings. ALMS1 encodes a large ubiquitously expressed protein that is associated with the centrosome and the basal body of primary cilium.

CURRENT RESEARCH

The localisation of ALMS1 to the ciliary basal body suggests its contribution to ciliogenesis and/or normal ciliary function, or centriolar stability. ALMS1 regulate glucose transport through the actin cytoskeleton, which plays an important role in insulin-stimulated GLUT4 transport. Both extreme IR and β-cell failure are the two determinant factors responsible for the development of glucose metabolism alterations in ALMS.

TREATMENT

Currently, there is no known cure for ALMS other than managing the underlying systemic diseases. When possible, individuals with ALMS and families should be referred to a centre of expertise and followed by a multidisciplinary team. Lifestyle modification, aerobic exercise and dietary induced weight loss are highly recommended as primary treatment for ALMS patients with T2DM and obesity.

CONCLUSION

Managing a rare disease requires not only medical care but also a support network including patient associations.

Clinical management of patients with genetic obesity during COVID-19 pandemic: position paper of the ESE Growth & Genetic Obesity COVID-19 Study Group and Rare Endo-ERN main thematic group on Growth and Obesity

This article aims to provide guidance on prevention and treatment of COVID-19 in patients with genetic obesity. Key principals of the management of patients with genetic obesity during COVID-19 pandemic for patients that have contracted COVID-19 are to be aware of: possible adrenal insufficiency (e.g., POMC deficiency, PWS); a more severe course in patients with concomitant immunodeficiency (e.g., LEP and LEPR deficiency), although defective leptin signalling could also be protective against the pro-inflammatory phenotype of COVID-19; disease severity being masked by insufficient awareness of symptoms in syndromic obesity patients with intellectual deficit (in particular PWS); to adjust medication dose to increased body size, preferably use dosing in m2; the high risk of malnutrition in patients with Sars-Cov2 infection, even in case of obesity. Key principals of the obesity management during the pandemic are to strive for optimal obesity management and a healthy lifestyle within the possibilities of the regulations to prevent weight (re)gain and to address anxiety within consultations, since prevalence of anxiety for COVID-19 is underestimated.

Relative Adipose Tissue Failure in Alström Syndrome Drives Obesity-Induced Insulin Resistance

Obesity is a major risk factor for insulin resistance (IR) and its attendant complications. The pathogenic mechanisms linking them remain poorly understood, partly due to a lack of intermediary monogenic human phenotypes. Here, we report on a monogenic form of IR-prone obesity, Alström syndrome (ALMS). Twenty-three subjects with monogenic or polygenic obesity underwent hyperinsulinemic-euglycemic clamping with concomitant adipose tissue (AT) microdialysis and an in-depth analysis of subcutaneous AT histology. We have shown a relative AT failure in a monogenic obese cohort, a finding supported by observations in a novel conditional mouse model (Alms ^flin/flin ) and ALMS1-silenced human primary adipocytes, whereas selective reactivation of ALMS1 gene in AT of an ALMS conditional knockdown mouse model (Alms ^flin/flin ; Adipo-Cre ^+/- ) restores systemic insulin sensitivity and glucose tolerance. Hence, we show for the first time the relative AT failure in human obese cohorts to be a major determinant of accelerated IR without evidence of lipodystrophy. These new insights into adipocyte-driven IR may assist development of AT-targeted therapeutic strategies for diabetes.

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.

Very high bone mineral density in a monogenic form of obesity-associated insulin resistance

INTRODUCTION

Alström syndrome (ALMS) is an ultra-rare metabolic disorder caused by biallelic loss-of-function in the Alms1 gene which encodes a ubiquitously expressed centrosomal protein of the primary cilium. Although ALMS is characterised by several metabolic and hormonal dysfunctions that can lead to an increased risk of developing osteoporosis and bone fracture, an increased BMD have been observed. The aim of this study was to characterise the anthropometric, clinical, genetic and densitometric features of bone health in a large adult UK cohort of subjects with ALMS.

METHODS

Twenty-three patients with ALMS and 23 age-matched male control subjects were recruited. Lumbar spine (LS) and total hip (TH) bone mineral density (BMD) were evaluated by DXA in all subjects. A CT scan to assess the spinal bone architecture was performed in ALMS patients with raised lumbar density. Blood analysis for biochemical parameters and thyroid and sex hormones was performed in all ALMS patients.

RESULTS

LS Z-score levels were higher than +2 SD in 35% of all ALMS study participants, of whom 75% were men and 25% were women. TH Z-scores were higher than +1 SD 13% of patients and all of them have higher than expected lumbar Z-score. An extremely high BMD was found in two of the oldest patients (LS Z-score +10.8 and +15.3 SD).

CONCLUSION

ALMS patients tend to have high levels of BMD that increase with age, in particular of the trabecular bones. Although obesity and lifelong IR can be responsible for the increase in BMD, at least in part, of a possible signalling role of Alms1 protein as a bone-forming factor is plausible.

Consensus clinical management guidelines for Alström syndrome

Alström Syndrome (ALMS) is an ultra-rare multisystem genetic disorder caused by autosomal recessive variants in the ALMS1 gene, which is located on chromosome 2p13. ALMS is a multisystem, progressive disease characterised by visual disturbance, hearing impairment, cardiomyopathy, childhood obesity, extreme insulin resistance, accelerated non-alcoholic fatty liver disease (NAFLD), renal dysfunction, respiratory disease, endocrine and urologic disorders. Clinical symptoms first appear in infancy with great variability in age of onset and severity. ALMS has an estimated incidence of 1 case per 1,000,000 live births and ethnically or geographically isolated populations have a higher-than-average frequency. The rarity and complexity of the syndrome and the lack of expertise can lead to delayed diagnosis, misdiagnosis and inadequate care. Multidisciplinary and multiprofessional teams of experts are essential for the management of patients with ALMS, as early diagnosis and intervention can slow the progression of multi-organ dysfunctions and improve patient quality of life.These guidelines are intended to define standard of care for patients suspected or diagnosed with ALMS of any age. All information contained in this document has originated from a systematic review of the literature and the experiences of the authors in their care of patients with ALMS. The Appraisal of Guidelines for Research & Evaluation (AGREE II) system was adopted for the development of the guidelines and for defining the related levels of evidence and strengths of recommendations.These guidelines are addressed to: a) specialist centres, other hospital-based medical teams and staffs involved with the care of ALMS patients, b) family physicians and other primary caregivers and c) patients and their families.

Survey of disorders of sex development in a large cohort of patients with diverse Mendelian phenotypes

Disorders of sex development (DSD) are congenital conditions with atypical development of chromosomal, gonadal, or anatomical sex. The estimated incidence ranges from 1 in 4,500-5,500 for strictly defined "ambiguous genitalia" to 1 in 300 or higher when a broader definition is implemented. In this study, we aim to define DSD phenotypes encountered in a large heterogeneous cohort of molecularly characterized Mendelian disorders in a single center. Data were retrieved for patients with documented abnormal genitalia based on the 2006 consensus criteria. Out of 149 patients (129 families) with compatible human phenotype ontology, 76 patients (68 families) had an identified genetic cause and were included in our analysis. Potentially causal variants were identified in 42 genes, and two patients had a dual molecular diagnosis. Six genes have no associated phenotype in OMIM (PIANP, CELSR2, USP2, FAM179B, TXNDC15, and CCDC96). Thirteen genes have non-DSD OMIM phenotypes, thus we are expanding their phenotype to include DSD. We also highlight how certain disorders are under-recognized despite their established DSD phenotype in OMIM, especially CTU2-related DREAM-PL syndrome and TSPYL1-related sudden infant death with dysgenesis of the testes syndrome. In conclusion, this study of a large heterogeneous Mendelian cohort expands the list of genes and disorders beyond those classically DSD-linked.

Cilia signaling and obesity

An emerging number of rare genetic disorders termed ciliopathies are associated with pediatric obesity. It is becoming clear that the mechanisms associated with cilia dysfunction and obesity in these syndromes are complex. In addition to ciliopathic syndromic forms of obesity, several cilia-associated signaling gene mutations also lead to morbid obesity. While cilia have critical and diverse functions in energy homeostasis including their roles in centrally mediated food intake as well as in peripheral tissues, many questions remain. Here, we briefly discuss the syndromic ciliopathies and monoallelic cilia signaling gene mutations associated with obesity. We also describe potential ways cilia may be involved in common obesity. We discuss how neuronal cilia impact food intake potentially through leptin signaling and changes in ciliary G protein-coupled receptor (GPCR) signaling. We highlight several recent studies that have implicated the potential for cilia in peripheral tissues such as adipose and the pancreas to contribute to metabolic dysfunction. Then we discuss the potential for cilia to impact energy homeostasis through their roles in both development and adult tissue homeostasis. The studies discussed in this review highlight how a comprehensive understanding of the requirement of cilia for the regulation of diverse biological functions will contribute to our understanding of common forms of obesity.

Childhood obesity and the associated rise in cardiometabolic complications

Childhood obesity is one of the most serious global public-health challenges of the twenty-first century. Over the past four decades, the number of children and adolescents with obesity has risen more than tenfold. Worldwide, an increasing number of youth are facing greater exposure to obesity throughout their lives, and this increase will contribute to the early development of type 2 diabetes, fatty liver and cardiovascular complications. Herein, we provide a brief overview of trends in the global shifts in, and environmental and genetic determinants of, childhood obesity. We then discuss recent progress in the elucidation of the central role of insulin resistance, the key element linking obesity and cardiovascular-risk-factor clustering, and the potential mechanisms through which ectopic lipid accumulation leads to insulin resistance and its associated cardiometabolic complications in obese adolescents. In the absence of effective prevention and intervention programs, childhood obesity will have severe public-health consequences for decades to come.

Clinical characteristics of individual organ system disease in non-motile ciliopathies

Non-motile ciliopathies (disorders of the primary cilia) include autosomal dominant and recessive polycystic kidney diseases, nephronophthisis, as well as multisystem disorders Joubert, Bardet-Biedl, Alström, Meckel-Gruber, oral-facial-digital syndromes, and Jeune chondrodysplasia and other skeletal ciliopathies. Chronic progressive disease of the kidneys, liver, and retina are common features in non-motile ciliopathies. Some ciliopathies also manifest neurological, skeletal, olfactory and auditory defects. Obesity and type 2 diabetes mellitus are characteristic features of Bardet-Biedl and Alström syndromes. Overlapping clinical features and molecular heterogeneity of these ciliopathies render their diagnoses challenging. In this review, we describe the clinical characteristics of individual organ disease for each ciliopathy and provide natural history data on kidney, liver, retinal disease progression and central nervous system function.

Tracing the effect of the melanocortin-4 receptor pathway in obesity: study design and methodology of the TEMPO registry

Purpose: The hypothalamic melanocortin-4 receptor (MC4R) pathway, a component of the central melanocortin pathway, regulates energy balance and satiety. Rare genetic disorders of obesity may be characterized by impaired MC4R pathway signaling, which results in early-onset severe obesity and insatiable hunger (hyperphagia). The TEMPO registry (NCT03479437) is a voluntary, prospective, open-ended registry of individuals with rare genetic disorders of obesity due to mutations in genes within the MC4R pathway who have early-onset severe obesity. The objective of the TEMPO registry is to evaluate the burden of rare genetic disorders of obesity on individuals, their parents/caregivers, health care providers, and the health care system.

Patients and methods: Individuals with rare genetic disorders of obesity (adults aged ≥18 years and children and adolescents aged from 2 to 17 years) will be referred by their health care providers or by a genetic screening study. Individuals must meet age- and sex-specific body mass index values that define the clinical criteria for severe obesity and carry selected variants in MC4R or in one of several genes upstream or downstream of the MC4R. Online surveys will be completed by the individual, parent/caregiver, and health care provider at baseline and annually thereafter and will collect data on demographics, results of genetic testing, medical/family history, disease characteristics, resource utilization, eating habits/hunger episodes, social and emotional impacts, and interest in future clinical trial participation.

Conclusions: The TEMPO registry will provide insights into the overall course and disease burden for individuals with rare genetic disorders of obesity. Health care providers may use this resource to improve the identification, diagnosis, and treatment of individuals with rare forms of genetic obesity.

Loss of function BMP4 mutation supports the implication of the BMP/TGF-β pathway in the etiology of combined pituitary hormone deficiency

Despite BMP4 signaling being critical to Rathke's pouch induction and maintenance during early stages of pituitary development, its implication in the etiology of combined pituitary hormone deficiency (CPHD) and other clinical presentations of congenital hypopituitarism has not yet been definitely demonstrated. We report here the first CPHD patient with a de novo pathogenic loss-of-function variant in BMP4. A 6-year-old boy, with macrocephaly, myopia/astigmatism, mild psychomotor retardation, anterior pituitary hypoplasia and ectopic posterior pituitary, clinically diagnosed with growth hormone deficiency, and central hypothyroidism, was referred for genetic analysis of CPHD. Targeted NGS analysis with a custom panel (n = 310 genes) identified a novel heterozygous de novo nonsense variant, NM_001202.5:c.794G > A, p.(Trp265*) in BMP4, which introduces a premature stop codon in the BMP4 pro-domain, impairing the transcription of the TGF-β mature peptide domain. Additional relevant variants in other genes implicated in pituitary development signaling pathways such as SMAD4 and E2F4 (BMP/TGF-pathway), ALMS1 (NOTCH-pathway), and TSHZ1 (Prokineticin-pathway), were also identified. Our results support the implication of the BMP/TGF-β signaling pathway in the etiology of CPHD and suggest that oligogenic contribution of additional inherited variants may modify the phenotypic expressivity of BMP4 pathogenic variants.

Alström syndrome: Renal findings in correlation with obesity, insulin resistance, dyslipidemia and cardiomyopathy in 38 patients prospectively evaluated at the NIH clinical center

Alström Syndrome is a ciliopathy associated with obesity, insulin resistance/type 2 diabetes mellitus, cardiomyopathy, retinal degeneration, hearing loss, progressive liver and kidney disease, and normal cognitive function. ALMS1, the protein defective in this disorder, localizes to the cytoskeleton, microtubule organizing center, as well as the centrosomes and ciliary basal bodies and plays roles in formation and maintenance of cilia, cell cycle regulation, and endosomal trafficking. Kidney disease in this disorder has not been well characterized. We performed comprehensive multisystem evaluations on 38 patients. Kidney function decreased progressively; eGFR varied inversely with age (p = 0.002). Eighteen percent met the definition for chronic kidney disease (eGFR < 60 mL/min/1.73 m² and proteinuria); all were adults with median age of 32.8 (20.6-37.9) years. After adjusting for age, there were no significant associations of kidney dysfunction with type 2 diabetes mellitus, dyslipidemia, hypertension, cardiomyopathy or portal hypertension suggesting that kidney disease in AS is a primary manifestation of the syndrome due to lack of ALMS1 protein. Approximately one-third of patients had hyperechogenicity of the renal parenchyma on imaging. While strict control of type 2 diabetes mellitus may decrease kidney-related morbidity and mortality in Alström syndrome, identification of novel targeted therapies is needed.