A review of Alström syndrome: a rare monogenic ciliopathy

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.

Advanced Chronic Kidney Disease (CKD) in a Patient With Alstrom Syndrome

Alstrom syndrome is an autosomal recessive disease. It affects multiple systems, including cardiovascular, renal, endocrine, and eyes. Our patient is a 25-year-old female who presented with elevated creatinine. Her past medical history was significant for hypothyroidism, polycystic ovarian syndrome, blindness, cataracts, hearing loss, and heart problems. She had genetic testing done that revealed that she was homozygous for the ALMS1 gene and was diagnosed with Alstrom syndrome. She was followed by nephrology in the clinic and had chronic kidney disease (CKD) stage V. The patient traveled to Italy and was lost to follow-up.

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.

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.

Persistent Prothrombotic State in a Patient With Alström Syndrome

We present the case of a patient with Alström syndrome who was found to have evidence of a prothrombotic state on autopsy after sudden cardiac death. To the best of our knowledge, this case of persistent prothrombotic milieu is the first described in a patient with Alström syndrome.

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.

The emerging functions of intraflagellar transport 52 in ciliary transport and ciliopathies

Ciliary transport in eukaryotic cells is an intricate and conserved process involving the coordinated assembly and functioning of a multiprotein intraflagellar transport (IFT) complex. Among the various IFT proteins, intraflagellar transport 52 (IFT52) plays a crucial role in ciliary transport and is implicated in various ciliopathies. IFT52 is a core component of the IFT-B complex that facilitates movement of cargoes along the ciliary axoneme. Stable binding of the IFT-B1 and IFT-B2 subcomplexes by IFT52 in the IFT-B complex regulates recycling of ciliary components and maintenance of ciliary functions such as signal transduction and molecular movement. Mutations in the IFT52 gene can disrupt ciliary trafficking, resulting in dysfunctional cilia and affecting cellular processes in ciliopathies. Such ciliopathies caused by IFT52 mutations exhibit a wide range of clinical features, including skeletal developmental abnormalities, retinal degeneration, respiratory failure and neurological abnormalities in affected individuals. Therefore, IFT52 serves as a promising biomarker for the diagnosis of various ciliopathies, including short-rib thoracic dysplasia 16 with or without polydactyly. Here, we provide an overview of the IFT52-mediated molecular mechanisms underlying ciliary transport and describe the IFT52 mutations that cause different disorders associated with cilia dysfunction.

Unraveling Alström syndrome: Homozygous mutation c.2729C>G in ALMS1 gene across an extended family

BACKGROUND

Alström syndrome (AS) represents an exceptionally rare genetic disorder characterized by a constellation of features including cardiomyopathy, progressive hearing and vision impairment, as well as obesity. This study seeks to elucidate the genetic underpinnings of this syndrome within the Saudi Arabian population.

METHODS

Employing an extended family cohort, we conducted an exhaustive molecular genetic assessment to delineate the presence of Alström syndrome. Additionally, we conducted an extensive review of existing literature from Saudi population to contextualize our findings within the broader understanding of the disorder in our country.

RESULTS

Within our studied extended family, we identified two individuals harboring the homozygous pathogenic mutation (c.2729C>G) in the ALMS1 gene [NM_015120.4:c.2729C>G (p.Ser910*)]. Notably, carrier status was observed in the parents, whereas some siblings exhibited typical alleles while others were carriers of the mutation. Intriguingly, a review of the literature unveiled six distinct reports documenting a total of 20 Alström syndrome patients within the Saudi Arabian population, each presenting with distinct novel mutations.

CONCLUSIONS

In cases featuring cardiomyopathy, obesity, and progressive hearing and vision loss, Alström syndrome merits inclusion within the differential diagnosis. To confirm the diagnosis, molecular genetic assessment of the ALMS1 gene is imperative, offering definitive clarity amidst the complex clinical presentation. This investigation reinforces the importance of genetic scrutiny for precise diagnosis and highlights the unique genetic landscape of Alström syndrome within the Saudi Arabian population.

Alström's Syndrome, Leber's Hereditary Optic Neuropathy, or Retinitis Pigmentosa? A Case of Misdiagnosis

A case of a patient with the Alström syndrome (AS) that was misdiagnosed as Leber's hereditary optic neuropathy or retinitis pigmentosa for 13 years is presented. AS is a rare genetic disorder caused by mutations in the ALMS1 gene. AS may lead to abnormal ciliary formation and function. AS affects metabolism, and symptomatology includes type 2 diabetes mellitus (T2DM), obesity, hypogonadism and gynecomastia in males, progressive bilateral sensorineural hearing loss, cardiomyopathy, nonalcoholic fatty liver disease (NAFLD), cirrhosis, and chronic progressive kidney disease. The onset of the above symptoms may vary significantly. The ophthalmic manifestation is early onset cone-rod dystrophy that starts as progressive vision loss, photophobia, and nystagmus in the first months of life. An accurate diagnosis may enable specialists to facilitate a significantly positive effect in the everyday life of a patient. Genetic counseling may also be recommended for these patients. Diagnosis was confirmed by DNA testing, thus highlighting its necessity in everyday practice.

Ancestry-driven metabolite variation provides insights into disease states in admixed populations

BACKGROUND

Metabolic pathways are related to physiological functions and disease states and are influenced by genetic variation and environmental factors. Hispanics/Latino individuals have ancestry-derived genomic regions (local ancestry) from their recent admixture that have been less characterized for associations with metabolite abundance and disease risk.

METHODS

We performed admixture mapping of 640 circulating metabolites in 3887 Hispanic/Latino individuals from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL). Metabolites were quantified in fasting serum through non-targeted mass spectrometry (MS) analysis using ultra-performance liquid chromatography-MS/MS. Replication was performed in 1856 nonoverlapping HCHS/SOL participants with metabolomic data.

RESULTS

By leveraging local ancestry, this study identified significant ancestry-enriched associations for 78 circulating metabolites at 484 independent regions, including 116 novel metabolite-genomic region associations that replicated in an independent sample. Among the main findings, we identified Native American enriched genomic regions at chromosomes 11 and 15, mapping to FADS1/FADS2 and LIPC, respectively, associated with reduced long-chain polyunsaturated fatty acid metabolites implicated in metabolic and inflammatory pathways. An African-derived genomic region at chromosome 2 was associated with N-acetylated amino acid metabolites. This region, mapped to ALMS1, is associated with chronic kidney disease, a disease that disproportionately burdens individuals of African descent.

CONCLUSIONS

Our findings provide important insights into differences in metabolite quantities related to ancestry in admixed populations including metabolites related to regulation of lipid polyunsaturated fatty acids and N-acetylated amino acids, which may have implications for common diseases in populations.

Genetic Obesity-Causes and Treatments

Genetic abnormalities are responsible for up to 70% of severe, early onset obesity. With recent advances in genetic testing, more individuals with genetic etiology of excessive weight are being identified. However, treatment will need to be individualized based on the cause and underlying pathophysiology. Several treatment options are being investigated, and there are several treatment options now commercially available for some of these genetic conditions. [Pediatr Ann. 2023;52(2):e57-e61.].

Identification of a novel mutation in ALMS1 in a Chinese patient with monogenic diabetic syndrome by whole-exome sequencing

Alstrom syndrome (AS) is one type of monogenic diabetic syndromes caused by mutation in the ALMS1. Due to rare prevalence and overlaps of clinical symptoms, monogenic diabetes is often misdiagnosed. Here, we report a Chinese diabetes patient with poor blood glucose control and insulin resistance. With whole-exome sequencing (WES), this patient was classified into monogenic diabetes and diagnosed as AS with one novel gene mutation identified. This study highlights the clinical application of WES in the diagnosis of monogenic diabetes.

Genetics of Obesity in Humans: A Clinical Review

Obesity is a complex multifactorial disorder with genetic and environmental factors. There is an increase in the worldwide prevalence of obesity in both developed and developing countries. The development of genome-wide association studies (GWAS) and next-generation sequencing (NGS) has increased the discovery of genetic associations and awareness of monogenic and polygenic causes of obesity. The genetics of obesity could be classified into syndromic and non-syndromic obesity. Prader-Willi, fragile X, Bardet-Biedl, Cohen, and Albright Hereditary Osteodystrophy (AHO) syndromes are examples of syndromic obesity, which are associated with developmental delay and early onset obesity. Non-syndromic obesity could be monogenic, polygenic, or chromosomal in origin. Monogenic obesity is caused by variants of single genes while polygenic obesity includes several genes with the involvement of members of gene families. New advances in genetic testing have led to the identification of obesity-related genes. Leptin (LEP), the leptin receptor (LEPR), proopiomelanocortin (POMC), prohormone convertase 1 (PCSK1), the melanocortin 4 receptor (MC4R), single-minded homolog 1 (SIM1), brain-derived neurotrophic factor (BDNF), and the neurotrophic tyrosine kinase receptor type 2 gene (NTRK2) have been reported as causative genes for obesity. NGS is now in use and emerging as a useful tool to search for candidate genes for obesity in clinical settings.

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.