Consensus clinical management guidelines for Alström syndrome

Identification of novel compound heterozygous variants of the ALMS1 gene in a child with Alström syndrome by whole genome sequencing

BACKGROUND

Alström syndrome (ALMS), a rare recessively inherited ciliopathy caused by mutations in ALMS1, is characterized by retinal dystrophy, childhood obesity, sensorineural hearing loss, and type 2 diabetes mellitus. The majority of pathogenic variants in ALMS1 are nonsense and frameshift mutations, which would lead to premature protein truncation, whereas copy number variants are seldom reported.

METHODS

Herein, we present a 10-year-old Chinese girl with ALMS. The potential causative genetic variant was confirmed through whole genome sequencing, quantitative real-time PCR analysis, and Sanger sequencing. Additionally, breakpoint analysis was performed to determine the exact breakpoint site of the large deletion and elucidate its probable formation mechanism.

RESULTS

The patient had a cor triatriatum sinister (CTS) structure. Genetic analysis identified novel compound heterozygous variants in the patient, consisting of a frameshift variant c.4414_4415delGT (p.V1472Nfs*26) in ALMS1 and a novel large deletion at chr2:73,612,355-73,626,339, which encompasses exon 1 of the ALMS1 gene. Moreover, breakpoint analysis revealed that the large deletion probably formed through the microhomology-mediated end joining (MMEJ) mechanism due to the 6-bp microhomologies (TCCTTC) observed at both ends of the breakpoints.

CONCLUSIONS

In this study, novel compound heterozygous variants in the ALMS1 gene were identified in an ALMS patient with a CTS structure. The molecular confirmation of these variants expands the mutational spectrum of ALMS1, while the manifestation of ALMS in the patient provides additional clinical insights into this syndrome.

Obesity: exploring its connection to brain function through genetic and genomic perspectives

Obesity represents an escalating global health burden with profound medical and economic impacts. The conventional perspective on obesity revolves around its classification as a "pure" metabolic disorder, marked by an imbalance between calorie consumption and energy expenditure. Present knowledge, however, recognizes the intricate interaction of rare or frequent genetic factors that favor the development of obesity, together with the emergence of neurodevelopmental and mental abnormalities, phenotypes that are modulated by environmental factors such as lifestyle. Thirty years of human genetic research has unveiled >20 genes, causing severe early-onset monogenic obesity and ~1000 loci associated with common polygenic obesity, most of those expressed in the brain, depicting obesity as a neurological and mental condition. Therefore, obesity's association with brain function should be better recognized. In this context, this review seeks to broaden the current perspective by elucidating the genetic determinants that contribute to both obesity and neurodevelopmental and mental dysfunctions. We conduct a detailed examination of recent genetic findings, correlating them with clinical and behavioral phenotypes associated with obesity. This includes how polygenic obesity, influenced by a myriad of genetic variants, impacts brain regions associated with addiction and reward, differentiating it from monogenic forms. The continuum between non-syndromic and syndromic monogenic obesity, with evidence from neurodevelopmental and cognitive assessments, is also addressed. Current therapeutic approaches that target these genetic mechanisms, yielding improved clinical outcomes and cognitive advantages, are discussed. To sum up, this review corroborates the genetic underpinnings of obesity, affirming its classification as a neurological disorder that may have broader implications for neurodevelopmental and mental conditions. It highlights the promising intersection of genetics, genomics, and neurobiology as a foundation for developing tailored medical approaches to treat obesity and its related neurological aspects.

Whole-exome sequencing revealed a novel mutation of the ALMS1 gene in a Chinese family with Alström syndrome: a case report

BACKGROUND

Alström syndrome (AS) is a rare autosomal recessive disorder that leads to multiple organ fibrosis and failure. Precise diagnosis from the clinical symptoms is challenging due to its highly variabilities and its frequent confusion with other ciliopathies and genetic diseases. Currently, mutations in the ALMS1 gene have been reported as a major cause of AS, thus, it is crucial to focus on the detection and discovery of ALMS1 mutations.

CASE PRESENTATION

We present a case of a 13-year-old Chinese boy weighing 70 kg and standing 168 cm tall. He has two younger brothers. Their parents hail from different ancestral homes in eastern and northern China. The patient's primary clinical findings included visual impairment at the age of four and progressive hearing loss starting at the age of ten. Subsequently, at the age of twelve, the patient developed hyperlipidaemia and hyperinsulinemia. Ultrasonographic findings indicated the presence of gallstones and mild fatty liver. His Body Mass Index (BMI) significantly increased to 25 kg/m2 (ref: 18.5-23.9 kg/m2). Additionally, echocardiography revealed mild mitral and tricuspid regurgitation. Ultimately, Whole Exome Sequencing (WES) identified a new missense mutation in the ALMS1 gene (NG_011690.1 (NM_015120): c.9536G > A (p.R3179Q)). This missense mutation generated an aberrant splicer and disrupted the stability and hydrophobicity of proteins, which preliminarily determined as " likely pathogenic". Therefore, considering all the above symptoms and molecular analysis, we deduced that the patient was diagnosed with AS according to the guidelines. We recommended that he continue wearing glasses and undergo an annual physical examination.

CONCLUSION

In this case report, we report a novel homozygous ALMS1 mutation associated with AS in the Chinese population, which expands the mutation spectrum of ALMS1. Genetic testing indeed should be incorporated into the diagnosis of syndromic deafness, as it can help avoid misdiagnoses of AS. While there is no specific treatment for AS, early diagnosis and intervention can alleviate the progression of some symptoms and improve patients' quality of life.

Adult syndromology: challenges, opportunities and perspectives: Illustrated by the description of four adults with Costello syndrome

Clinical geneticists and syndromologists have traditionally focused on identifying syndromes in children. However, there is a growing acknowledgment of the need to describe adult phenotypes. This article provides an overview of the evolving phenotypes of rare genetic syndromes into adulthood, elucidating its challenges, opportunities, and future perspectives. The clinical phenotypes of four adults with Costello syndrome are described to illustrate these aspects. Phenotypic and genotypic data from four individuals broaden the spectrum of Costello syndrome in adulthood and highlight the high variability in neurocognitive outcome. The clinical data align with previous findings and established genotype-phenotype correlations. Interestingly, two individuals presented with recurrent cancers (bladder cancer and neuroblastoma). Further studies are imperative to provide reliable information for counselling and management to enable comprehensive understanding of the evolving features of rare syndromic diseases and special health issues into adulthood.

A Comprehensive Review of Syndromic Forms of Obesity: Genetic Etiology, Clinical Features and Molecular Diagnosis

Syndromic obesity refers to obesity occurring with additional clinical findings, such as intellectual disability/developmental delay, dysmorphic features, and congenital malformations. PURPOSE OF REVIEW: To present a narrative review regarding the genetic etiology, clinical description, and molecular diagnosis of syndromic obesity, which is a rare condition with high phenotypic variability and genetic heterogeneity. The following syndromes are presented in this review: Prader-Willi, Bardet-Biedl, Pseudohypoparathyroidism, Alström, Smith-Magenis, Cohen, Temple, 1p36 deletion, 16p11.2 microdeletion, Kleefstra, SIM1-related, Börjeson-Forssman-Lehmann, WAGRO, Carpenter, MORM, and MYT1L-related syndromes. RECENT FINDINGS: There are three main groups of mechanisms for syndromic obesity: imprinting, transcriptional activity regulation, and cellular cilia function. For molecular diagnostic, methods of genome-wide investigation should be prioritized over sequencing of panels of syndromic obesity genes. In addition, we present novel syndromic conditions that need further delineation, but evidences suggest they have a higher frequency of obesity. The etiology of syndromic obesity tends to be linked to disrupted neurodevelopment (central) and is associated with a diversity of genes and biological pathways. In the genetic investigation of individuals with syndromic obesity, the possibility that the etiology of the syndromic condition is independent of obesity should be considered. The accurate genetic diagnosis impacts medical management, treatment, and prognosis, and allows proper genetic counseling.

Alström Syndrome: A Review Focusing on Its Diverse Clinical Manifestations and Their Etiology as a Ciliopathy

Alström syndrome is a form of inherited obesity caused by a single gene abnormality and is inherited as an autosomal recessive trait. It is characterised by a variety of clinical manifestations, including progressive visual and hearing impairment, type 2 diabetes mellitus, dilated cardiomyopathy, and hepatic and renal dysfunction, in addition to obesity. Recent insights underline the pivotal involvement of the disease-associated gene (ALMS1) in cilia formation and function, leading to the classification of its clinical manifestations as a ciliopathy. This review delineates the diverse clinical indicators defining the syndrome and elucidates its pathological underpinnings.

Alström Syndrome: A Challenging Case Study of a Female Saudi Patient With Type 2 Diabetes Mellitus and Complete Vision Loss

Alström syndrome is a genetic disease that impacts numerous systems in the human body. The symptoms can vary and appear gradually. Childhood obesity, heart disease (cardiomyopathy), abnormalities in vision, and hearing issues are the main symptoms of this disorder in children. Diabetes mellitus, hepatic issues, and renal dysfunction can all occur over time. Genetic alterations in the ALMS1 gene are the cause of Alström syndrome. It has an autosomal recessive inheritance pattern. We address the case of a Saudi woman in her 20s. She had been initially referred for type 2 diabetes, intellectual disability since early childhood, metabolic acidosis, and micrognathia; however, she also exhibited blindness, chronic kidney disease (CKD), and hearing loss, all of which are indicative of Alström syndrome. DNA testing showed that she has a homozygous pathogenic variant in the ALMS gene. Autosomal recessive Alström syndrome has been confirmed as a genetic diagnosis. No other clinically significant variations were found that are associated with the mentioned phenotype. By reporting this mutation, we hope to learn more about the genotypic range of the disease, particularly in the Saudi population. As each member of the family underwent genetic testing, we established a stringent follow-up schedule for our patient and her family.

Alström syndrome mimicking spasmus nutans: report of a novel ALMS1 variant

We report the case of an otherwise healthy 6-year-old girl presenting with poor visual acuity, photophobia, and abnormal eye and head movements who was initially diagnosed with spasmus nutans. A remote history of presumed viral cardiomyopathy and further electroretinography testing raised suspicion for Alström syndrome. She was diagnosed with a novel ALMS1 variant.

Phenoage and longitudinal changes on transthoracic echocardiography in Alström syndrome: a disease of accelerated ageing?

Alström syndrome (AS) is an ultra-rare disorder characterised by early-onset multi-organ dysfunction, such as insulin resistance, obesity, dyslipidaemia, and renal and cardiovascular disease. The objective is to explore whether AS is a disease of accelerated ageing and whether changes over time on echocardiography could reflect accelerated cardiac ageing. Cross-sectional measurement of Phenoage and retrospective analysis of serial echocardiography were performed between March 2012 and November 2022. The setting is a single national tertiary service jointly run by health service and patient charity. Forty-five adult patients aged over 16 years were included, 64% were male and 67% of White ethnicity. The median Phenoage was 48 years (interquartile range [IQR]: 35-72) in the 34 patients for whom this was calculable, which was significantly higher than the median chronological age of 29 years (IQR: 22-39, p<0.001). Phenoage was higher than chronological age in 85% (N=29) of patients, with a median difference of +18 years (IQR: +4, +34). On echocardiography, significant decreases were observed over time in left ventricular (LV) size at end-diastole (average of 0.046 cm per year, p<0.001) and end-systole (1.1% per year, p=0.025), with significant increase in posterior wall thickness at end-diastole (0.009 cm per year, p=0.008). LV systolic function measured by global longitudinal strain reduced (0.34 percentage points per year, p=0.020) and E/e'lat increased (2.5% per year, p=0.019). Most AS patients display a higher Phenoage compared to chronological age. Cardiac changes in AS patients were also reflective of accelerated ageing, with a reduction in LV size and increased wall thickening. AS may be a paradigm disease for premature ageing.

Glucagon-like peptide-1 analogues in monogenic syndromic obesity: Real-world data from a large cohort of Alström syndrome patients

AIM

To examine the real-world efficacy of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) in monogenic obesity in patients with Alström syndrome (ALMS).

METHODS

We screened 72 UK adult patients with ALMS and offered treatment to 34 patients meeting one of the following criteria: body mass index of 25 kg/m2 or higher, insulin resistance, suboptimal glycaemic control on antihyperglycaemic medications or non-alcoholic fatty liver disease.

RESULTS

In total, 30 patients, with a mean age of 31 ± 11 years and a male to-female ratio of 2:1, completed 6 months of treatment with GLP-1 RAs either in the form of semaglutide or exenatide. On average, treatment with GLP-1 RAs reduced body weight by 5.4 ± 1.7 (95% confidence interval [CI] 3.6-7) kg and HbA1c by 12 ± 3.3 (95% CI 8.7-15.3) mmol/mol, equating to 6% weight loss (P < .01) and 1.1% absolute reduction in HbA1c (P < .01). Significant improvements were also observed in serum total cholesterol, triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and alanine aminotransferase. The improvement of metabolic variables in our cohort of monogenic syndromic obesity was comparable with data for polygenic obesity, irrespective of weight loss.

CONCLUSIONS

Data from our centre highlight the non-inferiority of GLP-1 RAs in monogenic syndromic obesity to the available GLP-1 RA-use data in polygenic obesity, therefore, these agents can be considered as a treatment option in patients with ALMS, as well as other forms of monogenic obesity.

Syndromic and Monogenic Obesity: New Opportunities Due to Genetic-Based Pharmacological Treatment

Obesity is a significant health problem with a continuously increasing prevalence among children and adolescents that has become a modern pandemic during the last decades. Nowadays, the genetic contribution to obesity is well-established. For this narrative review article, we searched PubMed and Scopus databases for peer-reviewed research, review articles, and meta-analyses regarding the genetics of obesity and current pharmacological treatment, published in the English language with no time restrictions. We also screened the references of the selected articles for possible additional articles in order to include most of the key recent evidence. Our research was conducted between December 2022 and December 2023. We used the terms "obesity", "genetics", "monogenic", "syndromic", "drugs", "autosomal dominant", "autosomal recessive", "leptin-melanocortin pathway", and "children" in different combinations. Recognizing the genetic background in obesity can enhance the effectiveness of treatment. During the last years, intense research in the field of obesity treatment has increased the number of available drugs. This review analyzes the main categories of syndromic and monogenic obesity discussing current data on genetic-based pharmacological treatment of genetic obesity and highlighting the necessity that cases of genetic obesity should follow specific, pharmacological treatment based on their genetic background.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

Serum metabolomics identified specific lipid compounds which may serve as markers of disease progression in patients with Alström and Bardet-Biedl syndromes

Objectives: Alström syndrome (ALMS) and Bardet-Biedl syndrome (BBS) are among the so-called ciliopathies and are associated with the development of multiple systemic abnormalities, including early childhood obesity and progressive neurodegeneration. Given the progressive deterioration of patients' quality of life, in the absence of defined causal treatment, it seems reasonable to identify the metabolic background of these diseases and search for their progression markers. The aim of this study was to find metabolites characteristic to ALMS and BBS, correlating with clinical course parameters, and related to the diseases progression. Methods: Untargeted metabolomics of serum samples obtained from ALMS and BBS patients (study group; n = 21) and obese/healthy participants (control group; each of 35 participants; n = 70) was performed using LC-QTOF-MS method at the study onset and after 4 years of follow-up. Results: Significant differences in such metabolites as valine, acylcarnitines, sphingomyelins, phosphatidylethanolamines, phosphatidylcholines, as well as lysophosphatidylethanolamines and lysophosphatidylcholines were observed when the study group was compared to both control groups. After a follow-up of the study group, mainly changes in the levels of lysophospholipids and phospholipids (including oxidized phospholipids) were noted. In addition, in case of ALMS/BBS patients, correlations were observed between selected phospholipids and glucose metabolism parameters. We also found correlations of several LPEs with patients' age (p < 0.05), but the level of only one of them (hexacosanoic acid) correlated negatively with age in the ALMS/BBS group, but positively in the other groups. Conclusion: Patients with ALMS/BBS have altered lipid metabolism compared to controls or obese subjects. As the disease progresses, they show elevated levels of lipid oxidation products, which may suggest increased oxidative stress. Selected lipid metabolites may be considered as potential markers of progression of ALMS and BBS syndromes.

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.

Control of protein and lipid composition of photoreceptor outer segments-Implications for retinal disease

Vision is arguably our most important sense, and its loss brings substantial limitations to daily life for affected individuals. Light is perceived in retinal photoreceptors (PRs), which are highly specialized neurons subdivided into several compartments with distinct functions. The outer segments (OSs) of photoreceptors represent highly specialized primary ciliary compartments hosting the phototransduction cascade, which transforms incoming light into a neuronal signal. Retinal disease can result from various pathomechanisms originating in distinct subcompartments of the PR cell, or in the retinal pigment epithelium which supports the PRs. Dysfunction of primary cilia causes human disorders known as "ciliopathies", in which retinal disease is a common feature. This chapter focuses on PR OSs, discussing the mechanisms controlling their complex structure and composition. A sequence of tightly regulated sorting and trafficking events, both upstream of and within this ciliary compartment, ensures the establishment and maintenance of the adequate proteome and lipidome required for signaling in response to light. We discuss in particular our current understanding of the role of ciliopathy proteins involved in multi-protein complexes at the ciliary transition zone (CC2D2A) or BBSome (BBS1) and how their dysfunction causes retinal disease. While the loss of CC2D2A prevents the fusion of vesicles and delivery of the photopigment rhodopsin to the ciliary base, leading to early OS ultrastructural defects, BBS1 deficiency results in precocious accumulation of cholesterol in mutant OSs and decreased visual function preceding morphological changes. These distinct pathomechanisms underscore the central role of ciliary proteins involved in multiple processes controlling OS protein and lipid composition.

Searching for Effective Methods of Diagnosing Nervous System Lesions in Patients with Alström and Bardet-Biedl Syndromes

Bardet-Biedl syndrome (BBS) and Alström syndrome (ALMS) are rare multisystem diseases with an autosomal recessive mode of inheritance and genetic heterogeneity, characterized by visual impairment, hearing impairment, cardiomyopathy, childhood obesity, and insulin resistance. The purpose of our study was to evaluate the indicators of nervous system changes occurring in patients with ALMS and BBS using optical coherence tomography (OCT) and magnetic resonance spectroscopy (MRS) methods compared to a group of healthy subjects. The OCT results showed significantly lower macular thickness in the patient group compared to the control group (p = 0.002). The MRS study observed differences in metabolite levels between the study and control groups in brain areas such as the cerebellum, thalamus, and white matter. After summing the concentrations from all areas, statistically significant results were obtained for N-acetylaspartate, total N-acetylaspartate, and total creatine. Concentrations of these metabolites were reduced in ALMS/BBS patients by 38% (p = 0.0004), 35% (p = 0.0008), and 28% (p = 0.0005), respectively. Our results may help to understand the pathophysiology of these rare diseases and identify strategies for 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.

Cohen Syndrome: Novel VPS13B Genetic Variants in a Male Portuguese Patient with Pigmentary Retinopathy

The purpose of this clinical report was to describe a case of Cohen syndrome with its classical ophthalmological manifestations and novel VPS13B genetic variants. A 39-year-old Caucasian male patient with severe rod-cone retinal dystrophy and no history of parental consanguinity was referred to our ophthalmology department. Ophthalmologic history included high bilateral myopia and a 3-year prior bilateral cataract surgery. Systemic history included facial dysmorphism, intellectual disability, transient neutropenia, microcephaly, truncal obesity, and joint hyperextensibility. The patient presented classic fundoscopic features of pigmentary retinopathy in both eyes (OU). Optical coherence tomography (OCT) revealed bilateral central and diffuse retinal pigment epithelium (RPE) and outer retinal atrophy without concomitant macular edema, while fluorescein angiography (FA) demonstrated diffuse RPE atrophy with prominent choroidal vessels. The full-field ERG (ffERG) showed no dark-adapted or light-adapted responses and the P50 wave was not identified in the pattern ERG (pERG). The genetic study revealed two novel heterozygous variants in the VPS13B gene: (1) c.5138T>C p.(Leu1713Pro) and (2) c.10179del p.(Asn3393Lysfs*37), thus confirming the diagnosis of Cohen syndrome. This case report introduces these two novel genetic variants to the literature, in a patient with classic phenotypic characteristics of Cohen syndrome, a rare genetic disease which has been increasingly reported since its first description in 1973.

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

A Rare Cause of Infantile-Onset Cardiomyopathy With Ocular Manifestations: Alström Syndrome

We report a case of a five-month-old girl, who presented to our hospital with increased work of breathing, sweating since birth, and abnormal eye movements. On further evaluation, she was found to have restrictive cardiomyopathy, nystagmus, and hypotonia. Genetic workup showed a pathogenic variant in the ALSM1 gene, which confirmed the diagnosis of Alström syndrome. Alström syndrome is a rare condition that is characterized by a wide variety of multisystem manifestations, including visual disturbances, hearing impairment, and cardiomyopathy. This case report highlights Alström syndrome as one of the rare causes of early-onset infantile cardiomyopathy with nystagmus.

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.

New pathogenic variants of ALMS1 gene in two Chinese families with Alström Syndrome

Purpose

Alström Syndrome (AS) is an autosomal recessive hereditary disease with the characteristics of multiorgan dysfunction. Due to the heterogeneity of clinical manifestations of AS, genetic testing is crucial for the diagnosis of AS. Herein, we used whole-exome sequencing (WES) to determine the genetic causes and characterize the clinical features of three affected patients in two Chinese families with Alström Syndrome.

Materials and methods

Three affected patients (initially diagnosed as achromatopsia). and five asymptomatic members were recruited for both genetic and clinical tests. The complete ophthalmic examinations and systemic examinations were performed on all participants. Whole exome sequencing (WES) was performed for mutation detection. The silico analysis was also applied to predict the pathogenesis of identified pathogenic variants.

Results

In family 1, the proband showed low vision, hyperopia, photophobia, nystagmus, and total color blindness. DNA analysis revealed that she carried a compound heterozygote with two novel pathogenic variants in the ALMS1 gene NM_015120.4:c.10379del (NP_055935.4:p.(Asp2252Tyr)) and NM_015120.4:c.11641_11642del (NP_055935.4:p.(Val3881ThrfsTer11)). Further systemic examinations showed short stature, acanthosis nigricans, and sensorineural hearing loss. In family 2, two affected siblings presented the low vision, hyperopia, photophobia, nystagmus, and total color blindness. DNA analysis revealed that they carried a same compound heterozygote with two novel pathogenic variants in the ALMS1 gene NM_015120.4:c.10379del (NP_055935.4:p.(Asn3460IlefsTer49)), NM_015120.4:c.10819C > T (NP_055935.4:p.(Arg3607Trp)). Further systemic examinations showed obesity and mild abnormalities of lipid metabolism. According to the genetic testing results and further systemic analysis, the three affected patients were finally diagnosed as Alström Syndrome (AS).

Conclusions

We found two new compound heterozygous pathogenic variants of the ALMS1 gene and determined the diagnosis as Alström Syndrome in three patients of two Chinese families. Our study extends the genotypic and phenotypic spectrums for ALMS1 -AS and emphasizes the importance of gene testing in assisting the clinical diagnosis for cases with phenotypic diversities, which would help the AS patients with early diagnosis and treatment to reduce future systemic damage.

Prepubertal onset of type 2 diabetes in Shashi-Pena syndrome due to ASXL2 mutation

Type 2 diabetes remains rare in the pediatric population and the majority of cases occur during puberty. A combination of genetic and environmental factors leads to the development of insulin resistance and β-cell failure. An increased prevalence is recognized in a number of rare genetic disorders such as Alström and Bardet-Biedl syndromes. Recently, a rare neurodevelopmental disorder, Shashi-Pena syndrome due to the dominant negative effect of heterozygous mutations in additional Sex-Combs-Like Genes 2 (ASXL2) has been reported. ASXL2 null mice exhibit glucose intolerance, insulin resistance and lipodystrophy. The regulatory role of ASXL2 in glucose and lipid homeostasis occurs through its interaction with peroxisome proliferator-activated receptor gamma (PPARγ), a gene implicated in the pathogenesis of type 2 diabetes on genome-wide association studies. Thiazolidinediones, used for the treatment of type 2 diabetes, exert their effects as direct agonists of PPARγ. We report the first case of type 2 diabetes in Shashi-Pena syndrome, occurring in an 8-year-old prepubertal boy with no family history. In addition, the proband had dyslipidemia, and fatty infiltration of the liver with elevated transaminases. Mutation of ASXL2 in humans, through its interaction with PPARγ appears to cause a phenotype of insulin resistance, type 2 diabetes, and dyslipidemia. Further reported cases will assist in confirming this association.

PATAS, a First-in-Class Therapeutic Peptide Biologic, Improves Whole-Body Insulin Resistance and Associated Comorbidities In Vivo

Adipose tissue is a key regulator of whole-body metabolic fitness because of its role in controlling insulin sensitivity. Obesity is associated with hypertrophic adipocytes with impaired glucose absorption, a phenomenon existing in the ultrarare monogenic disorder Alström syndrome consisting of severe insulin resistance. Inactivation of ALMS1 directly inhibits insulin-mediated glucose absorption in the white adipose tissue and induces severe insulin resistance, which leads to type 2 diabetes, accelerated nonalcoholic liver disease, and fibrosis. These phenotypes were reversed by specific adipocyte-ALMS1 reactivation in vivo. Subsequently, ALMS1 was found to bind to protein kinase C-α (PKCα) in the adipocyte, and upon insulin signaling, PKCα is released from ALMS1. α-Helices in the kinase domain of PKCα were therefore screened to identify a peptide sequence that interfered with the ALMS1-PKCα protein interaction. When incubated with cultured human adipocytes, the stapled peptide termed PATAS, for Peptide derived of PKC Alpha Targeting AlmS, triggered insulin-independent glucose absorption, de novo lipogenesis, and cellular glucose utilization. In vivo, PATAS reduced whole-body insulin resistance, and improved glucose intolerance, fasting glucose, liver steatosis, and fibrosis in rodents. Thus, PATAS represents a novel first-in-class peptide that targets the adipocyte to ameliorate insulin resistance and its associated comorbidities.

Genetics behind Cerebral Disease with Ocular Comorbidity: Finding Parallels between the Brain and Eye Molecular Pathology

Cerebral visual impairments (CVIs) is an umbrella term that categorizes miscellaneous visual defects with parallel genetic brain disorders. While the manifestations of CVIs are diverse and ambiguous, molecular diagnostics stand out as a powerful approach for understanding pathomechanisms in CVIs. Nevertheless, the characterization of CVI disease cohorts has been fragmented and lacks integration. By revisiting the genome-wide and phenome-wide association studies (GWAS and PheWAS), we clustered a handful of renowned CVIs into five ontology groups, namely ciliopathies (Joubert syndrome, Bardet-Biedl syndrome, Alstrom syndrome), demyelination diseases (multiple sclerosis, Alexander disease, Pelizaeus-Merzbacher disease), transcriptional deregulation diseases (Mowat-Wilson disease, Pitt-Hopkins disease, Rett syndrome, Cockayne syndrome, X-linked alpha-thalassaemia mental retardation), compromised peroxisome disorders (Zellweger spectrum disorder, Refsum disease), and channelopathies (neuromyelitis optica spectrum disorder), and reviewed several mutation hotspots currently found to be associated with the CVIs. Moreover, we discussed the common manifestations in the brain and the eye, and collated animal study findings to discuss plausible gene editing strategies for future CVI correction.

Alström Syndrome with Early Vision and Hearing Impairement

Alström syndrome (ALMS) is an autosomal recessive disorder characterized by multiple organ involvement, including progressive cone-rod dystrophy, sensorineural hearing loss, childhood obesity, and type 2 diabetes mellitus. Pathogenic variants in the ALMS1 gene are the known cause for the occurrence of this devastating condition. Here we report on a 12 year old boy referred to the University Clinic with early signs of impaired hearing and vision, obesity, and scoliosis. Central vision was first affected, followed by peripheral vision. In addition, his weight began increasing after the age of two years, reaching 78 kg at a height of 157 cm (BMI 31.64). No polydactyly was present. His mental development was normal in spite of his hearing and vision impairments. There was acanthosis nigricans on the neck. ECG and the cardiac ultrasound were normal. At the age of 12 years, his testicles are 12 ml and his pubertal status is P2 A2. OGTT revealed impaired glucose tolerance with elevated insulin concentrations 121ulU/mL (reference range 2,00-29,1 ulU/mL). Renal function was unaffected, liver functions were normal. Uric acid and lipids were within normal plasma concentrations. A Whole Exome Sequencing was performed and a homozygous ALMS1 pathogenic, frameshift gene variant (LRG_741t1(ALMS1):c.4156dup; p.Thr1386AsnfsTer15) was determined as the cause of the disease. Both parents were carriers for the variant. The absence of mental retardation and polydactyly differentiates Alström and Bardet-Biedle syndrome.

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.

Whole-exome sequencing establishes a diagnosis of Alstrom syndrome: a case report

BACKGROUND

Alstrom syndrome (ALMS) is a rare genetic disorder. ALMS is characterized by progressive bilateral sensorineural hearing impairment, cone-rod dystrophy, infantile-onset cardiomyopathy, hypertriglyceridemia, accelerated non-alcoholic fatty liver disease, renal dysfunction and insulin-resistant diabetes mellitus (DM). DM typically develop in childhood or adolescence. Dilated cardiomyopathy may arise in infancy. Clinical symptoms appear with great variability and severity. Several cases have been reported worldwide; however, diagnosis remains challenging.

CASE DESCRIPTION

We report an 8-year-and-11-month-old female diagnosed with ALMS who had a long history of obesity and amblyopia from infancy. We found high levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in this patient. She showed no hearing disfunction. Recently, she presented with sudden-onset insulin-resistant DM. Genetic analysis revealed the heterozygous mutations c.8366delT, p.L2789* and c.6829C>T, p.R2277*. c.8366delT, which results in premature protein termination, has not been reported previously in ALMS1. Although the patient's two sisters died of acute heart failure following infection at 4 and 14 months respectively, she showed no signs of cardiomyopathy until now.

CONCLUSIONS

This case provides an unusual cause of genetic syndrome associated with diabetes. A detailed medical history, physical examination and appropriate gene analysis are critical for diagnosis. Our case identifies a novel ALMS1 mutation and reaffirms the great clinical variation of this disease even within families.

A novel variant site of Alstrom syndrome in a Chinese child: a case report

BACKGROUND

Alstrom syndrome (ALMS) is an ultra-rare multisystem genetic disorder caused by autosomal recessive inheritance of the ALMS1 gene. It manifests as multisystem dysfunction, displaying unique clinical signs and symptoms and various severity, which may lead to delayed prognosis or misdiagnosis in medical practice. Although almost 300 pathogenic variants have been reported, there are some variant sites that have not been recognized yet.

CASE DESCRIPTION

We report a case of a 14-year-old boy with manifestations, including binocular vision loss, acanthosis nigricans, type 2 diabetes, insulin resistance, elevated transaminase, hepatic fibrosis, and proteinuria. Compound heterozygous variants in the ALMS1 gene have been discovered by whole exon sequencing. One of his variant sites was C. 8158C>T, which was from his father. And the other variant site was C. 3575C>A, which was from his mother. To the great of our knowledge, this site has not been reported before. Both of the variants make the synthesis of the peptide chain terminated in advance and an incomplete polypeptide chain is formed.

CONCLUSIONS

The clinical presentations of ALMS are complicated and varied. Although early diagnosis can be made according to typical clinical symptoms, whole exon sequencing is necessary for the diagnosis of ALMS, as indicated by our study.

Neovascularization of the optic disc and peripheral retinal ischemia in a child with a novel variant in ALMS1 (Alström syndrome)

Purpose

The ophthalmologic findings in Alström syndrome include cone-rod dystrophy, optic atrophy, optic disc drusen, and retinal telangiectasias with exudative retinopathy. Here we describe peripheral retinal non-perfusion with neovascularization of the disc (NVD) in a child with Alström syndrome-related cone-rod dystrophy.

Observations

A six-year-old girl with a diagnosis of Alström syndrome based on a homozygous nonsense likely pathogenic variant in ALMS1 (NM_015120.4:c.4746C > G; p.Tyr1582Ter) was seen in the ophthalmology clinic for nystagmus, photophobia, and poor vision with non-recordable scotopic and photopic electroretinography (ERG) responses. On routine follow-up exam, she was found to have optic disc hyperermia and apparent swelling. Brain and orbital magnetic resonance imaging (MRI) and lumbar puncture with opening pressure measurement were unremarkable. Because the optic disc findings were persistent, she underwent examination under anesthesia with fluorescein angiography, which revealed bilateral neovascularization of the optic disc (NVD) with peripheral retinal non-perfusion. Systemic workup including hemoglobin A1C measurement was normal. She underwent four sessions of bilateral panretinal photocoagulation and three intravitreal injections of anti-vascular endothelial growth factor (VEGF) with subsequent improvement of the NVD in both eyes.

Conclusions and importance

Neovascularization of the optic disc may arise in Alström syndrome as a sequela of peripheral retinal ischemia. This finding may be partially responsive to panretinal photocoagulation and intravitreal anti-VEGF therapy.

Novel mutations of the Alström syndrome 1 gene in an infant with dilated cardiomyopathy: A case report

BACKGROUND

Alström syndrome (AS) is a rare autosomal recessive disease that is generally induced by mutations of the Alström syndrome 1 (ALMS1) gene. We report a case of AS, extend the spectrum of ALMS1 mutations and highlight the biological role of ALMS1 to explore the relationship between dilated cardiomyopathy (DCM) and mutations in ALMS1.

CASE SUMMARY

We present the case of an infant with AS mainly manifesting with DCM that was caused by a novel mutation of the ALMS1 gene. Whole-exome sequencing revealed a simultaneous large deletion and point mutation in ALMS1, leading to frameshift and missense mutations, respectively, rather than nonsense or frameshift mutations, which have been reported previously. Upon optimized anti-remodeling therapy, biohumoral exams and arrhythmic burden of the infant were alleviated at follow-up after 6 mo.

CONCLUSION

We identified novel mutations of ALMS1 and extended the spectrum of ALMS1 mutations in an infant with AS.

Molecular and Phenotypic Expansion of Alström Syndrome in Chinese Patients

Alström syndrome (ALMS) is a rare inherited metabolic disease and ciliopathy. Large cohorts of ALMS are lacking around the world. Detailed genetic and phenotypic data were obtained from all affected individuals. Olfactory function was evaluated by the Chinese Smell Identification Test and facial pattern was analyzed with Face2gene. Fifty ALMS patients were included in this study, aged from 0.3 to 21.7 years old. Sixty-one ALMS1 variants in 50 patients from 47 different families were confirmed, including 59 truncating and two exon deletions. Twenty-four of those variants were novel. We also summarized all previously reported cases of Chinese ALMS patients (69 patients) and identified specific and common variants within the Chinese population. Besides, the Chinese Smell Identification Test scores in patients was lower than that in controls (11.97 Vs. 10.44, p < .05), indicating olfactory identification impairments in ALMS patients. The facial pattern in ALMS patients was also distinctive from that of the controls (p < .05). In conclusion, this is the largest cohort of Chinese ALMS patients. We have successfully identified both specific and common variants in our cohort. We found a new phenotype of olfactory impairments in ALMS patients through a case-control study.

Usher Syndrome

Usher syndrome (USH) is the most common genetic condition responsible for combined loss of hearing and vision. Balance disorders and bilateral vestibular areflexia are also observed in some cases. The syndrome was first described by Albrecht von Graefe in 1858, but later named by Charles Usher, who presented a large number of cases with hearing loss and retinopathy in 1914. USH has been grouped into three main clinical types: 1, 2, and 3, which are caused by mutations in different genes and are further divided into different subtypes. To date, nine causative genes have been identified and confirmed as responsible for the syndrome when mutated: MYO7A, USH1C, CDH23, PCDH15, and USH1G (SANS) for Usher type 1; USH2A, ADGRV1, and WHRN for Usher type 2; CLRN1 for Usher type 3. USH is inherited in an autosomal recessive pattern. Digenic, bi-allelic, and polygenic forms have also been reported, in addition to dominant or nonsyndromic forms of genetic mutations. This narrative review reports the causative forms, diagnosis, prognosis, epidemiology, rehabilitation, research, and new treatments of USH.

Alstrom's Syndrome: An Experience of Tertiary Care Center

Alstrom's syndrome (AS) is an autosomal recessively inherited multisystemic disorder that falls under the umbrella of ciliopathy. It is characterized by poor vision, hearing impairment, cardiomyopathy, childhood obesity, diabetes mellitus type 2, dyslipidemia, pulmonary, hepatic, and renal failure besides systemic fibrosis. Biallelic pathogenic variants in ALMS1 gene cause AS. Retrospective study (1990–2017) included 12 Saudi patients with AS based on their phenotype, biochemical markers, and genotype. The study was approved by Fisal Specialist Hospital and Research Centre, Riyadh (RAC number 2131129) on October 2, 2012. This study showed clinical and genetic heterogeneity; six patients showed a founder mutation (IVS18–2A > T in exon 19), whereas six others showed private mutations. AS in Saudi Arabia is underdiagnosed probably because of its variable clinical manifestations. We report 12 Saudi patients with AS to enhance the awareness about this syndrome.

Amiodarone-induced multiple organ damage in an Alström syndrome patient with end-stage renal disease and hepatic cirrhosis

Alström syndrome (AS) is an extremely rare disease accompanied by blindness, hearing loss, obesity, type 2 diabetes, dilated cardiomyopathy, and progressive hepatic and renal dysfunction. The life span of AS patients rarely exceeds 50 years, and thus there are very few reports describing the implementation of renal replacement therapy for these patients. We here report a case of AS patient who exhibited dilated cardiomyopathy, end-stage renal disease, and hepatic cirrhosis. He underwent hemodialysis therapy more than 3 years. Although he eventually died of amiodarone-induced multiple organ damage in the lungs and liver, the present case suggests that hemodialysis therapy can be a choice of renal replacement therapy for AS patients with end-stage renal disease.

Alström syndrome with a novel mutation of ALMS1 and Graves’ hyperthyroidism: A case report and review of the literature

BACKGROUND

Alström syndrome (AS, OMIM ID 203800) is a rare disease involving multiple organs in children and is mostly reported in non-Chinese patients. In the Chinese population, there are few reports on the clinical manifestations and pathogenesis of AS. This is the first report on the association between AS and Graves’ hyperthyroidism.

CASE SUMMARY

An 8-year-old Chinese girl was diagnosed with AS. Two years later, Graves’ hyperthyroidism developed with progressive liver dysfunction. The patient’s clinical data were collected; DNA from peripheral blood of the proband, parents and sibling was collected for gene mutation detection using the second-generation sequencing method and gene panel for diabetes. The association between the patient’s genotype and clinical phenotype was analyzed. She carried the pathogenic compound heterozygous mutation of ALMS1 (c.2296_2299del4 and c.11460C>A). These stop-gain mutations likely caused truncation of the ALMS1 protein.

CONCLUSION

The manifestation of hyperthyroidism may suggest rapid progression of AS.

Liver Fibrosis and Steatosis in Alström Syndrome: A Genetic Model for Metabolic Syndrome

Alström syndrome (ALMS) is an ultra-rare monogenic disease characterized by insulin resistance, multi-organ fibrosis, obesity, type 2 diabetes mellitus (T2DM), and hypertriglyceridemia with high and early incidence of non-alcoholic fatty liver disease (NAFLD). We evaluated liver fibrosis quantifying liver stiffness (LS) by shear wave elastography (SWE) and steatosis using ultrasound sonographic (US) liver/kidney ratios (L/K) in 18 patients with ALMS and 25 controls, and analyzed the contribution of metabolic and genetic alterations in NAFLD progression. We also genetically characterized patients. LS and L/K values were significantly higher in patients compared with in controls (p < 0.001 versus p = 0.013). In patients, LS correlated with the Fibrosis-4 Index and age, while L/K was associated with triglyceride levels. LS showed an increasing trend in patients with metabolic comorbidities and displayed a significant correlation with waist circumference, the homeostasis model assessment, and glycated hemoglobin A1c. SWE and US represent promising tools to accurately evaluate early liver fibrosis and steatosis in adults and children with ALMS during follow-up. We described a new pathogenic variant of exon 8 in ALMS1. Patients with ALMS displayed enhanced steatosis, an early increased age-dependent LS that is associated with obesity and T2DM but also linked to genetic alterations, suggesting that ALMS1 could be involved in liver fibrogenesis.

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.

Prevalent ALMS1 Pathogenic Variants in Spanish Alström Patients

Alström syndrome (ALMS) is an ultrarare disease with an estimated prevalence lower than 1 in 1,000,000. It is associated with disease-causing mutations in the Alström syndrome 1 (ALMS1) gene, which codifies for a structural protein of the basal body and centrosomes. The symptomatology involves nystagmus, type 2 diabetes mellitus (T2D), obesity, dilated cardiomyopathy (DCM), neurodegenerative disorders and multiorgan fibrosis. We refined the clinical and genetic diagnosis data of 12 patients from 11 families, all of them from Spain. We also studied the allelic frequency of the different variants present in this cohort and performed a haplotype analysis for the most prevalent allele. The genetic analysis revealed 2 novel homozygous variants located in the exon 8, p.(Glu929Ter) and p.(His1808GlufsTer20) in 2 unrelated patients. These 2 novel variants were classified as pathogenic after an in silico experiment (computer analysis). On the other hand, 2 alleles were detected at a high frequency in our cohort: p.(Tyr1714Ter) (25%) and p.(Ser3872TyrfsTer19) (16.7%). The segregation analysis showed that the pathogenic variant p.(Tyr1714Ter) in 3 families is linked to a rare missense polymorphism, p.(Asn1787Asp). In conclusion, 2 novel pathological mutations have been discovered in homozygosis, as well as a probable founder effect in 3 unrelated families.

Neurocognitive assessment and DNA sequencing expand the phenotype and genotype spectrum of Alström syndrome

Alström syndrome (OMIM#203800) is an ultra-rare autosomal recessive monogenic disease presenting pathogenic variants in ALMS1 (chromosome 2p13). It is characterized by early onset of blindness, hearing loss and systemic comorbidities, with delayed development without cognitive impairment. We aimed to investigate the cognitive functions and describe new pathogenic variants in Alström syndrome patients. Nineteen patients (13 adults, 6 children) underwent a thorough clinical, genetic, laboratory, instrumental, and neurocognitive assessment. Six new pathogenic variants in ALMS1 including the first described in exon 6 were identified. Four patients displayed a "mild phenotype" characterized by slow disease onset or absence of complications, including childhood obesity and association with at least one pathogenic variant in exon 5 or 6. At neurocognitive testing, a significant proportion of patients had deficits in three neurocognitive domains: similarities, phonological memory, and apraxia. In particular, 53% of patients showed difficulties in the auditory working memory test. We found ideomotor and buccofacial apraxia in 74% of patients. "Mild phenotype" patients performed better on auditory working memory and ideomotor apraxia test than "typical phenotype" ones (91.9 + 16.3% vs. 41.7 + 34.5% of correct answers, Z = 64.5, p < .01 and 92.5 + 9.6 vs. 61.7 + 26.3, Z = 61, p < .05, respectively). Deficits in auditory working memory, ideomotor, and buccofacial apraxia were found in these patients and fewer neuropsychological deficits were found in the "mild" phenotype group. Furthermore, in the "mild" phenotype group, it was found that all pathogenic variants are localized before exon 8.

Identification of a Rare Exon 19 Skipping Mutation in ALMS1 Gene in Alström Syndrome Patients From Two Unrelated Saudi Families

Background: Alström syndrome (AS) is a very rare childhood disorder characterized by cardiomyopathy, progressive hearing loss and blindness. Inherited genetic variants of ALMS1 gene are the known molecular cause of this disease. The objective of this study was to characterize the genetic basis and understand the genotype-phenotype relationship in Saudi AS patients. Methods: Clinical phenotyping and whole-exome sequencing (WES) analysis were performed on six AS patients belonging to two unrelated consanguineous Saudi families. Sanger sequencing was performed to determine the mode of inheritance of ALMS1 variant in first-degree family relatives and also to ensure its rare prevalence in 100 healthy population controls. Results: We identified that Alström patients from both the families were sharing a very rare ALMS1, 3'-splice site acceptor (c.11873-2 A>T) variant, which skips entire exon-19 and shortens the protein by 80 amino acids. This disease variant was inherited by AS patients in autosomal recessive mode and is not yet reported in any population-specific genetic databases. AS patients carrying this mutation showed heterogeneity in clinical presentations. Computational analysis of the mutant centroid structure of ALMS1 mRNA revealed that exon-19 skipping enlarges the hairpin loop and decreases the free energy, eventually affecting its folding pattern, stability, and function. Hence, we propose c.11873-2A as an AS causative potential founder mutation in Saudi Arabia because it is found in two families lacking a common lineage. Conclusions: We conclude that WES analysis potentially helps in clinical phenotyping, early diagnosis, and better clinical management of Alström patients showing variable clinical expressivity.