Alström Syndrome Research Articles

Presence of known feline ALMS1 and MYBPC3 variants in a diverse cohort of cats with hypertrophic cardiomyopathy in Japan.

Hypertrophic cardiomyopathy (HCM) is the most common heart disease in cats with a suspected genetic origin. Previous studies have identified five HCM-associated variants in three genes (Myosin binding protein C3: MYBPC3 p.A31P, p.A74T, p.R820W; Myosin heavy chain 7: MYH7 p.E1883K; Alstrom syndrome protein 1: ALMS1 p.G3376R). These variants are considered breed-specific, with the exception of MYBPC3 p.A74T, and have rarely been found in other breeds. However, genetic studies on HCM-associated variants across breeds are still insufficient because of population and breed bias caused by differences in genetic background. This study investigates the ubiquitous occurrence of HCM-associated genetic variants among cat breeds, using 57 HCM-affected, 19 HCM-unaffected, and 227 non-examined cats from the Japanese population. Genotyping of the five variants revealed the presence of MYBPC3 p.A31P and ALMS1 p.G3376R in two (Munchkin and Scottish Fold) and five non-specific breeds (American Shorthair, Exotic Shorthair, Minuet, Munchkin and Scottish Fold), respectively, in which the variants had not been identified previously. In addition, our results indicate that the ALMS1 variants identified in the Sphynx breed might not be Sphynx-specific. Overall, our results suggest that these two specific variants may still be found in other cat breeds and should be examined in detail in a population-driven manner. Furthermore, applying genetic testing to Munchkin and Scottish Fold, the breeds with both MYBPC3 and ALMS1 variants, will help prevent the development of new HCM-affected cat colonies.

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.

A novel missense ALMS1 variant causes aberrant splicing identified in a cohort of patients with Alström syndrome.

Purpose: Alström syndrome (AS) is a rare autosomal recessive disorder caused by variants of ALMS1. The objectives of this study were to describe the clinical and genetic characteristics of 19 Chinese patients with biallelic variants in ALMS1. Methods: We recruited 19 probands with biallelic disease-causing ALMS1 variants. All patients underwent ophthalmic and systematic evaluations and comprehensive molecular genetic analysis. Reverse transcriptase-polymerase chain reaction (RT-PCR) assays were performed to observe the effect of a novel missense variant on ALMS1 pre-mRNA splicing. Results: We identified 33 causative variants in ALMS1, including 15 frameshift small indels, 14 non-sense variants, two gross deletions, one splicing variant, and one missense variant. RT-PCR showed that the missense variant c.9542G>A (p.R3181Q) altered pre-mRNA splicing to generate a truncated protein p. (Ser3082Asnfs*6). Retinal dystrophy (RD) was noted in all the patients, followed by metabolism disturbance (obesity or acanthosis nigricans) in 66.7% and hearing impairment in 61.1% of the patients. Patient systemic symptom numbers and their age at evaluation showed a significant positive correlation, and BCVA and age at the last examination showed a moderate correlation. All patients exhibited early-onset RD and severe visual impairment. The exception was one patient carrying homozygous p. R3181Q, who showed a mild visual defect and atypical retinal phenotype. Conclusion: Our findings expand the pathogenic variant spectrum of ALMS1 and provide the first verification of a novel missense variant caused AS by aberrant pre-mRNA splicing. Patients with AS might demonstrate varied clinical spectra; therefore, genetic analysis is vital for the early and accurate diagnosis of patients with atypical AS.

Myocardiopathy in siblings as initial manifestation of Alstrom Syndrome: Report of two cases

Myocardiopathy in siblings as initial manifestation of Alstrom Syndrome: Report of two cases

Proteomic and Transcriptomic Landscapes of Alström and Bardet-Biedl Syndromes.

Alström syndrome (ALMS) and Bardet-Biedl syndrome (BBS) are rare genetic diseases with a number of common clinical features ranging from early-childhood obesity and retinal degeneration. ALMS and BBS belong to the ciliopathies, which are known to have the expression products of genes, encoding them as cilia-localized proteins in multiple target organs. The aim of this study was to perform transcriptomic and proteomic analysis on cellular models of ALMS and BBS syndromes to identify common and distinct pathological mechanisms present in both syndromes. For this purpose, epithelial cells were isolated from the urine of patients and healthy subjects, which were then cultured and reprogrammed into induced pluripotent stem (iPS) cells. The pathways of genes associated with the metabolism of lipids and glycosaminoglycan and the transport of small molecules were found to be concomitantly downregulated in both diseases, while transcripts related to signal transduction, the immune system, cell cycle control and DNA replication and repair were upregulated. Furthermore, protein pathways associated with autophagy, apoptosis, cilium assembly and Gli1 protein were upregulated in both ciliopathies. These results provide new insights into the common and divergent pathogenic pathways between two similar genetic syndromes, particularly in relation to primary cilium function and abnormalities in cell differentiation.

Ocular findings and genetic test in Alström syndrome in childhood.

This study aimed to investigate the mutation spectrums and ocular features of Alström syndrome (AS) patients. Six AS patients from five unrelated families were included. Ocular and systemic examinations were performed in all subjects. Whole-exome sequencing (WES) was performed in the probands, and Sanger sequencing was performed for mutation validation and segregation analysis. Among the six patients, the first symptoms included nystagmus, poor fixation, and photophobia. Five patients had high hyperopia, four of whom (80%) were initially diagnosed with amblyopia before referral with prescribed corrective lenses and amblyopia treatment, but no improvement was obtained. Optical coherence tomography (OCT) revealed progressive damage to the photoreceptor layer, including blurred ellipsoid zone (EZ) and lack of interdigitation zone (IZ) within the macula, and thorough loss of photoreceptor layer in the peripheral retina. Electroretinograms (ERG) demonstrated severely diminished cone and rod responses. WES identified biallelic variants of ALMS1 in all the six patients, including two novels, c.3892C>T (p.Gln1298*) and c.2888_2897del (p.Ser963Thrfs*15) and five knowns, c.10819C>T (p.Arg3607Trp), c.2090C>A (p.Ser697*), c.4891C>T (p.Gln1631*), c.10825C>T (p.Arg3069*) and c.6430C>T (Arg2146*). In conclusion, this study expanded the ocular features and genotypic spectrum of AS. High hyperopia is a significant and common feature of AS. OCT and ERG are essential accessory techniques for the diagnosis of AS. If a patient had high hyperopia with a noneffective response to amblyopic treatment, the diagnosis of AS should be suspected, and detailed ocular examination, systemic evaluation, and genetic testing recommended.

Association of circulating miRNAS in patients with Alstrőm and Bardet-Biedl syndromes with clinical course parameters.

Patients with the rare syndromic forms of monogenic diabetes: Alström syndrome (ALMS) and Bardet-Biedl syndrome (BBS) have multiple metabolic abnormalities, including early-onset obesity, insulin resistance, lipid disorders and type 2 diabetes mellitus. The aim of this study was to determine if the expression of circulating miRNAs in patients with ALMS and BBS differs from that in healthy and obese individuals and determine if miRNA levels correlate with metabolic tests, BMI-SDS and patient age. We quantified miRNA expression (Qiagen, Germany) in four groups of patients: with ALMS (n=13), with BBS (n=7), patients with obesity (n=19) and controls (n=23). Clinical parameters including lipids profile, serum creatinine, cystatin C, fasting glucose, insulin and C-peptide levels, HbA1c values and insulin resistance (HOMA-IR) were assessed in patients with ALMS and BBS. We observed multiple up- or downregulated miRNAs in both ALMS and BBS patients compared to obese patients and controls, but only 1 miRNA (miR-301a-3p) differed significantly and in the same direction in ALMS and BBS relative to the other groups. Similarly, 1 miRNA (miR-92b-3p) was dysregulated in the opposite directions in ALMS and BBS patients, but diverged from 2 other groups. We found eight miRNAs (miR-30a-5p, miR-92b-3p, miR-99a-5p, miR-122-5p, miR-192-5p, miR-193a-5p, miR-199a-3p and miR-205-5p) that significantly correlated with at least of the analyzed clinical variables representing an association with the course of the diseases. Our results show for the first time that serum miRNAs can be used as available indicators of disease course in patients with ALMS and BBS syndromes.

Proteomics of Plasma from Patients with Sickle Cell Disease with and without Chronic Pain: A Pilot Biomarker Discovery Study

Background Acute, severe, episodic nociceptive pain, or vaso-occlusive crises (VOCs) have been the hallmark of sickle cell disease (SCD), and responsible for >90% of health care encounters for this population. The concept that SCD patients experience a period of "normalcy" without any pain between these episodes of varying frequency has been challenged by several studies in the past two decades. It has been shown that ~30% of adults with SCD have chronic pain, defined as pain >50% of time for at least 6 months (Smith et al, 2008). The evolution of chronic pain is age dependent, and likely involves several different mechanisms. Studies in transgenic mouse models have shown that one mechanism involves neurogenic inflammation, triggered by mast cell activation (Vincent et al, 2013), through mediators such as tryptase and substance P. In a previous study (Albo et al, 2021) it was shown that patients with SCD and chronic pain had higher plasma levels of Tryptase and substance P, consistent with mast cell activation and neurogenic inflammation. Additionally, nerve growth factor (NGS), which has been incriminated in the pathophysiology of several chronic pain syndromes, was also found to be significantly elevated in the plasma of SCD patients with chronic pain. In this study, we conducted a pilot proteomics study of plasma samples from patients with and without chronic pain collected during the Albo et al study, and stored at -80 C. Methods IRB approval was obtained, and informed consent was obtained from 72 patients enrolled in the study, whose plasma were stored. Discovery proteomics was conducted on 20 plasma samples from two groups (10 with chronic pain, 10 without chronic pain) through semiquantitative LC/MS/MS proteomics on the Thermo Fisher Orbitrap Mass Spectrometer. Samples were subjected to affinity depletion of major proteins to discern out lower concentration proteins. Filters were then utilized to remove excess proteins using two rules; a protein that only showed up in one patient and proteins that were not present in at least 5 patients. Differential expression was then used to yield proteins significantly different between the chronic pain and non-chronic pain groups Results Table 1 shows the demographics, hydroxyurea therapy, opioid use, and pain scores of the 20 subjects included in the pilot study. Mass spectrometry of 20 samples revealed 5219 individual proteins. The filters cut down the protein count to 417, and differential expression yielded 16 proteins that were significantly different between the two groups. These included alpha-1 antitrypsin, Hepatocyte growth factor receptor, creatine kinase M-type, serine/threonine protein kinase SMG1, F-box only protein, Alstrom syndrome protein, beta transforming growth factor, serine/threonine protein mTOR, apolipoprotein C-1, keratin gylceraldehyde 3 phosphate dehydrogenase, Nesprin 1, retinol binding protein 3, Protein Wnt 16, multiple inositol polyphosphate phosphatase, immunoglobulin J-chain. Figure 1 demonstrates a heat map of these proteins down regulated and upregulated expression. Conclusion This pilot study has yielded 16 differentially expressed proteins in the plasma of SCD patients with and without chronic pain. Validation of these findings in a larger cohort are under way. It is hoped that if confirmed, these findings will lead to the identification of biomarkers for chronic pain in SCD. In addition to the potential utility of these biomarkers in differential diagnosis of pain syndromes in SCD, targets for therapeutic intervention could also be identified. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Abstract 11817: Induced Pluripotent Stem Cell-Derived Cardiac Disease Modeling for Studying Mitogenic Cardiomyopathy in Alström Syndrome

Introduction: Cardiomyopathies are a prominent cause of heart failure and affect millions of people worldwide. We reported two case studies describing siblings with a mutation in the Alström 1 (ALMS1) gene causing Alström syndrome (ALMS), who developed mitogenic cardiomyopathy, characterized by delayed postnatal cardiomyocyte (CM) cell cycle arrest resulting in neonatal heart failure and death in early infancy. OBJECTIVES : To generate induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) from ALMS patients and investigate molecular mechanisms of persistent CM proliferation in co-culture with ALMS1 fibroblasts. METHODS : We reprogrammed somatic cells from ALMS patients with mitogenic cardiomyopathy into iPSCs using Sendai virus technology and generated ALMS-specific iPSC-CMs using established in vitro differentiation protocols. We analyzed cell cycle progression by determining CM percentages in the G0/G1, S and G2/M phase using flow cytometry, and measured expression and secretion of periostin (POSTN) and collagens from ALMS1 fibroblasts in the extracellular matrix (ECM) using RT-QPCR and western blot. Finally, we investigated Hippo signaling by measuring expression and nuclear translocation of its downstream effectors YAP/TAZ using western blot and immunostaining. RESULTS : iPSC-CMs were successfully generated from ALMS patients and controls. ALMS1-deficient iPSC-CMs exhibited impaired ability to undergo cell cycle arrest, evidenced by a higher cell percentage in the G2/M phase. Furthermore, increased ECM levels of POSTN, a potent regulator of CM proliferation, were observed in co-cultures of ALMS1-deficient iPSC-CMs and ALMS1 fibroblasts. Finally, we found preliminary evidence of dysregulation of the Hippo pathway with altered cellular localization of YAP, and dysregulated total YAP and phosphorylated YAP. CONCLUSION : ALMS1-deficient iPSC-CMs recapitulate persistent postnatal proliferation observed in ALMS patients with mitogenic cardiomyopathy. Increased POSTN in the ECM and altered downstream Hippo signaling contribute to the mitogenic phenotype and suggest critical cues for future therapies aiming at stimulating CM turnover, a much-sought objective in cardiac repair to improve contractile function.

Depletion of ALMS1 affects TGF-β signalling pathway and downstream processes such as cell migration and adhesion capacity

Background: ALMS1 is a ubiquitous gene associated with Alström syndrome (ALMS). The main symptoms of ALMS affect multiple organs and tissues, generating at last, multi-organic fibrosis in the lungs, kidneys and liver. TGF-β is one of the main pathways implicated in fibrosis, controlling the cell cycle, apoptosis, cell migration, cell adhesion and epithelial-mesenchymal transition (EMT). Nevertheless, the role of ALMS1 gene in fibrosis generation and other implicated processes such as cell migration or cell adhesion via the TGF- β pathway has not been elucidated yet. Methods: Initially, we evaluated how depletion of ALMS1 affects different processes like apoptosis, cell cycle and mitochondrial activity in HeLa cells. Then, we performed proteomic profiling with TGF-β stimuli in HeLa ALMS1 -/- cells and validated the results by examining different EMT biomarkers using qPCR. The expression of these EMT biomarkers were also studied in hTERT-BJ-5ta ALMS1 -/-. Finally, we evaluated the SMAD3 and SMAD2 phosphorylation and cell migration capacity in both models. Results: Depletion of ALMS1 generated apoptosis resistance to thapsigargin (THAP) and C2-Ceramide (C2-C), and G2/M cell cycle arrest in HeLa cells. For mitochondrial activity, results did not show significant differences between ALMS1 +/+ and ALMS1 -/-. Proteomic results showed inhibition of downstream pathways regulated by TGF-β. The protein-coding genes (PCG) were associated with processes like focal adhesion or cell-substrate adherens junction in HeLa. SNAI1 showed an opposite pattern to what would be expected when activating the EMT in HeLa and BJ-5ta. Finally, in BJ-5ta model a reduced activation of SMAD3 but not SMAD2 were also observed. In HeLa model no alterations in the canonical TGF-β pathway were observed but both cell lines showed a reduction in migration capacity. Conclusion: ALMS1 has a role in controlling the cell cycle and the apoptosis processes. Moreover, the depletion of ALMS1 affects the signal transduction through the TGF-β and other processes like the cell migration and adhesion capacity.

Genetic obesity: an update with emerging therapeutic approaches.

Based on the genetic contribution, childhood obesity can be classified into 3 groups: common polygenic obesity, syndromic obesity, and monogenic obesity. More genetic causes of obesity are being identified along with the advances in the genetic testing. Genetic obesities including syndromic and monogenic obesity should be suspected and evaluated in children with early-onset morbid obesity and hyperphagia under 5 years of age. Patients with syndromic obesity have early-onset severe obesity associated specific genetic syndromes including Prader-Willi syndrome, Bardet-Biedle syndrome, and Alstrom syndrome. Syndromic obesity is often accompanied with neurodevelopmental delay or dysmorphic features. Nonsyndromic monogenic obesity is caused by variants in single gene which are usually involved in the regulation of hunger and satiety associated with the hypothalamic leptin-melanocortin pathway in central nervous system. Unlike syndromic obesity, patients with monogenic obesity usually show normal neurodevelopment. They would be presented with hyperphagia and early-onset severe obesity with additional clinical symptoms including short stature, red hair, adrenal insufficiency, hypothyroidism, hypogonadism, pituitary insufficiencies, diabetes insipidus, increased predisposition to infection or intractable recurrent diarrhea. Identifying patients with genetic obesity is critical as new innovative therapies including melanocortin 4 receptor agonist have become available. Early genetic evaluation enables to identify treatable obesity and provide timely intervention which may eventually achieve favorable outcome by establishing personalized management.

Alström syndrome: Two clinical cases with two novel pathogenic variants.

To report two clinical cases of Alström syndrome (AS) with novel pathogenic variant of the ALMS1 gene not previously reported. Patient 1 was a 6-year-old female presenting with poor vision. Ophthalmic examination only showed a visual field (VF) with diffusely decreased sensitivity in both eyes. At age of 15, vision and ophthalmic examination remain stable. Patient 2 was a 2-year-old male with poor vision, photophobia, and nystagmus. ERG showed a severe decrease in cone and rod responses. At age of 6, his vision is lower than 0.1 (decimal scale) and VF is severely constricted. Both of them presented with dilated cardiomyopathy in their first's months of life and patient 2 developed sensorineural deafness along with follow-up. Research genetic testing revealed two loss-of-function heterozygous genetic variants in the ALMS1 gene in both patients, so the diagnosis of AS was made. AS is a rare disease caused by pathogenic variants of ALMS1 gene that causes ocular manifestations in almost 100% of patients. There are many genetic variants of AMLS1 described, but novel pathogenic variants can still be found. Ophthalmologists play an important role in the diagnosis, and AS should be included in the differential diagnosis when retinal dystrophy is suspected.

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.

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

ObjectivesCausative 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 methodsIn 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. ResultsLower 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. ConclusionsThe 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.

Diagnosing Alström syndrome in a patient followed up with syndromic obesity for years.

Alström syndrome (AS) is a rare autosomal recessive monogenic disorder caused by mutations of the Alström syndrome 1 (ALMS1) gene, located on chromosome 2p13. It is a progressive multisystemic disease characterized mostly by obesity, sensorineural hearing loss, visual impairments, cardiomyopathy, insulin resistance and/or type 2 diabetes mellitus (T2DM), metabolic dysfunctions, non-alcoholic fatty liver disease, and chronic progressive kidney disease. Generally, the first clinical symptoms of the disease appear in the first years of life with a major variation of onset age. In this study, we aimed to examine the molecular diagnosis of a 6-year-old patient with suspected AS clinical symptoms. After applying clinical exome sequencing (CES) in the patient we found a homozygous deletion in exon 8 at the ALMS1 gene (c.2311_2312del). We identified a homozygous frameshift mutation. The reported variant was pathogenic according to the criteria of the American College of Medical Genetics and Genomics (ACMG). Thus, the patient was diagnosed with AS as a result of the combined clinical phenotype and genetic tests results. We hope the variant we found can expand the spectrum of ALMS1 variants in AS.

The first reported pregnancy and birth by a patient affected by Alstrom Syndrome: a case report

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Expression of ALMS1 in podocytes: possible role in filtration function

Previously, we identified Alstrom Syndrome 1 (ALMS1) as an interacting partner of NKCC2 in the Thick Ascending limb of the loop of Henle (TAL). Mutations in the ALMS1 gene in humans cause Alström syndrome, characterized by progressive metabolic alterations that include obesity, hypertension, and chronic kidney disease (CDK). SNPs in ALMS1 are associated with lower GFR in GWAS. However, role of ALMS1 in glomerular filtration has not been studied. We hypothesized that ALMS1 is expressed in glomerular podocytes where it may play a role in podocyte filtration function. To begin studying this, we localized ALMS1 expression to podocytes by immunofluorescence labeling of Actinin‐4, abundantly expressed in podocytes, and ALMS1. Confocal imaging showed that ALMS1 is co‐localized with Actinin‐4 in rat podocytes. In addition, ALMS1 was also expressed in an immortalized mouse podocyte cell line, as was Actinin‐4 and nephrin, as measured by Western blot and immunofluorescence microscopy. To determine if ALMS1 plays a role in podocyte pathology we measured nephrin expression in ALMS1 KO rats. These rats were generated in the Dahl SS genetic background and are hypertensive on a normal salt diet. We found that nephrin expression in renal cortical lysates was decreased by 61±08% (p&lt;0.05, n=7) in ALMS1 KO rats. To study if ALMS1 deletion could play a role in filtration barrier function we measured albumin/creatinine ratio in urine samples from 14‐16 weeks old wild type (WT) and ALMS1 KO rats. In ALMS1 KO rats, urinary albumin excretion was higher than control rats (WT: 4±2; ALMS1 KO: 26±6, n=6, p&lt;0.05). Taken together, our data show that ALMS1 is expressed in rat and mouse podocytes where it may play a role in filtration barrier function by maintaining podocyte biology.

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.

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.

Abstract MP212: Integrated Genomics Analysis Identifies Recessive Ciliopathy Mutations In Primary Endocardial Fibroelastosis: A Rare Neonatal Cardiomyopathy

Background: Among neonatal cardiomyopathies, primary endocardial fibroelastosis (pEFE) remains a mysterious disease of the endomyocardium, affecting 1/5000 live births and accounting for 25% of the entire pediatric dilated cardiomyopathy (DCM) population with a devastating course and grave prognosis. Objective: We aimed to investigate potential genetic contributions to pEFE etiology. Methods: We performed integrative genomic analysis in 8 infants with confirmed pathological diagnosis of pEFE using whole exome sequencing (WES), RNA-seq and functional genomics studies. Patient-derived fibroblasts, neonatal rat ventricular myocytes and neonatal rat cardiac fibroblasts were used for cellular assays. Real-time cell migration and proliferation analyses were performed using xCELLigence technology. Results: Whole exome sequencing detected novel and deleterious de novo single nucleotide variants, or inherited homozygous rare variants in 11 cilia-related genes in seven out of the eight affected probands. In particular, a novel homozygous variant [c.1938delA] in ALMS1 was identified in a female proband, pEFE4. This variant resulted in a frameshift introducing a premature stop codon and complete absence of the ALMS1 protein in the proband fibroblasts and explanted heart. Loss of function mutations of ALMS1 have been implicated in Alstrom syndrome [OMIM 203800], a rare recessive ciliopathy. RNA-sequencing of the proband’s dermal fibroblasts revealed significantly dysregulated cellular signaling and function, including the induction of epithelial mesenchymal transition (EMT), potentially mediated by TGFβ signaling activation. The proband fibroblasts exhibited enhanced migration activity. Herein, we present the unique pathological features of pEFE compared to DCM and utilize integrated WES with RNA-seq analysis to elucidate the molecular mechanisms by which the novel causal ALMS1 variant contributes to the unique pathology of pEFE in a female infant with Alstrom syndrome. Conclusions: Our report provides insights into pEFE etiology and suggests, for the first time to our knowledge, ciliopathy as a potential underlying mechanism for this poorly understood and incurable form of neonatal cardiomyopathy.