New variants of ALMS1 gene and familial Alstrom syndrome case series
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PROVIDER: S-EPMC10912837 | biostudies-literature | 2024 Jan
REPOSITORIES: biostudies-literature
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Project description:Alström Syndrome (ALMS), a recessive, monogenic ciliopathy caused by mutations in ALMS1, is typically characterized by multisystem involvement including early cone-rod retinal dystrophy and blindness, hearing loss, childhood obesity, type 2 diabetes mellitus, cardiomyopathy, fibrosis, and multiple organ failure. The precise function of ALMS1 remains elusive, but roles in endosomal and ciliary transport and cell cycle regulation have been shown. The aim of our study was to further define the spectrum of ALMS1 mutations in patients with clinical features of ALMS. Mutational analysis in a world-wide cohort of 204 families identified 109 novel mutations, extending the number of known ALMS1 mutations to 239 and highlighting the allelic heterogeneity of this disorder. This study represents the most comprehensive mutation analysis in patients with ALMS, identifying the largest number of novel mutations in a single study worldwide. Here, we also provide an overview of all ALMS1 mutations identified to date.
| S-EPMC4475486 | biostudies-literature
Project description:The Alstrom syndrome gene (ALMS1) is one of the largest disease associated genes identified today in the human genome and is implicated in cell cycle control, ciliogenesis, endosome recycling and intracellular transport mechanisms. ALMS1 mutations cause Alstrom syndrome, a rare genetic disorder. However, its function is not completely understood. DNA microarray analysis suggested that ALMS1 might be differentially expressed between Hodgkin lymphoma (HL) cells and normal tissues. By using reverse transcription-polymerase chain reaction (RT-PCR) we detected low but variable expression of ALMS1 in HL cell lines with highest expression in KM-H2 cells. Immunofluorescence indicated centrosomal accumulation of ALMS1 protein in HL cells. Knock-down of ALMS1 in KM-H2 cells had no impact on viability or cytotoxic drug sensitivity of these cells. Sequencing of RT-PCR products from HL cell lines identified three variable regions in ALMS1 transcripts that affect exons 2, 13, and 23. One of these variants was characterized by splicing out of exon 13. The other variants are characterized by two alternative 5 prime ends or alternative 3 prime ends. Structure prediction of the corresponding RNAs and proteins suggest that the different transcript variants might affect posttranscriptional regulation and ligand binding.
| S-EPMC5279758 | biostudies-literature
Project description:Mutations in the human ALMS1 gene cause Alström syndrome (AS), a progressive disease characterized by neurosensory deficits and by metabolic defects including childhood obesity, hyperinsulinemia and Type 2 diabetes. Other features that are more variable in expressivity include dilated cardiomyopathy, hypertriglyceridemia, hypercholesterolemia, scoliosis, developmental delay and pulmonary and urological dysfunctions. ALMS1 encodes a ubiquitously expressed protein of unknown function. To obtain an animal model in which the etiology of the observed pathologies could be further studied, we generated a mouse model using an Alms1 gene-trapped ES cell line. Alms1-/- mice develop features similar to patients with AS, including obesity, hypogonadism, hyperinsulinemia, retinal dysfunction and late-onset hearing loss. Insulin resistance and increased body weight are apparent between 8 and 12 weeks of age, with hyperglycemia manifesting at approximately 16 weeks of age. In addition, Alms1-/- mice have normal hearing until 8 months of age, after which they display abnormal auditory brainstem responses. Diminished cone ERG b-wave response is observed early, followed by the degeneration of photoreceptor cells. Electron microscopy revealed accumulation of intracellular vesicles in the inner segments of photoreceptors, whereas immunohistochemical analysis showed mislocalization of rhodopsin to the outer nuclear layer. These findings suggest that ALMS1 has a role in intracellular trafficking.
| S-EPMC2862911 | biostudies-literature
Project description:Objective Alström syndrome is an autosomal recessive genetic disease caused by a mutation in the ALMS1 gene. Alström syndrome is clinically characterized by multisystem involvement, including sensorineural deafness, cone-rod dystrophy, nystagmus, obesity, insulin resistance, type 2 diabetes and hypogonadism. The diagnosis is thus challenging for patients without this characteristic set of clinical symptoms. We explored the effectiveness of whole-exome sequencing in the diagnosis of Alström syndrome. Methods A girl with symptoms of Alström syndrome was tested and diagnosed with the disease by whole-exome sequencing. Results Whole-exome sequencing revealed two novel variants, c.6160_6161insAT: p.Lys2054Asnfs*21 (exon 8) and c.10823_10824 delAG:p.Glu 3608Alafs*9 (exon16) in the ALMS1 gene, leading to premature termination codons and the domain of ALMS1 protein. Blood sample testing of her asymptomatic parents revealed them to be heterozygous carriers of the same mutations. Assembly showed that the mutations on both alleles were located in conserved sequences. A review of the ALMS1 gene nonsense mutation status was performed. Conclusion We herein report two novel variants of the ALMS1 gene discovered in a Chinese Alström syndrome patient that expand the mutational spectrum of ALMS1 and provided new insight into the molecular mechanism underlying Alström syndrome. Our findings add to the current knowledge concerning the diagnosis and treatment of Alström syndrome.
| S-EPMC8710367 | biostudies-literature
Project description: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.
| S-EPMC7920446 | biostudies-literature
Project description:Alström syndrome (AS, OMIM ID 203800) is a rare childhood multiorgan disorder, which is widely studied in non-Arab ethnic patients. The clinical and molecular basis of AS and the mode of disease inheritance in consanguineous Arab populations is not well investigated. Therefore, to identify the molecular basis of AS in familial forms, the present study performed whole exome sequencing of 5 AS patients belonging to 2 different Bedouin families from Saudi Arabia. The present study identified the AS causative rare biallelic mutations in ALMS gene:T376S in exon 5 and S909* in exon 8 for family A and an R2721* in exon 10 (R2721*) for family B. ALMS1 targeted genetic sequencing of healthy population controls and family members has confirmed its extremely rare frequency and autosomal recessive mode of inheritance. The truncating mutations S909* and R2721* could cause the loss of CC domains and ALMS motif on C-terminal end of the protein and creates unstable protein, which eventually undergoes intracellular degradation. The premature protein truncating mutations described in our study may eventually provide further insight into the functional domains of the ALMS1 protein and contribute to the understanding of the phenotypic spectrum of AS. Whole exome sequencing based molecular diagnosis is expected to rule out ambiguity surrounding clinical diagnosis of suspected AS cases.
| S-EPMC6933154 | biostudies-literature
Project description:PurposeAlström syndrome (AS) is a rare monogenic autosomal recessively inherited disorder characterized by cone rod dystrophy and multiple organ dysfunction. Mutations in the Alström syndrome 1 (ALMS1) gene have been found to be causative for AS. The purpose of this study was to identify ALMS1 mutations and to assess the clinical features of Chinese patients with AS.MethodsDetailed ocular and laboratory examinations were performed. Peripheral blood samples were collected from patients and their parents. Genomic DNA was extracted with a Qiagen kit. Exons and exon/intron junctions of ALMS1 were amplified with polymerase chain reaction (PCR) and screened for mutations with Sanger sequencing. The results were compared with the ALMS1 transcript to exclude polymorphisms and confirm pathogenic mutations.ResultsSeven patients from five unrelated non-consanguineous families were diagnosed with AS. All patients had cone rod dystrophy with impaired visual acuity, photophobia, and nystagmus. Other clinical features, including sensorineural hearing loss, truncal obesity, insulin resistance, type 2 diabetes mellitus, renal and hepatic dysfunction, hyperlipidemia, hypothyroidism, mental retardation, acanthosis nigricans, and scoliosis, were present. Sequencing revealed two novel mutations, p.N3150Kfs2X and p.V3154Xfs, in patient 1; one novel mutation, p.N3672Ifs11X, and one previously reported nonsense mutation, p.R3703X, in patient 2; novel mutations p.S2479X and p.R3611Efs7X in patient 3; one novel homozygous mutation, p.S695X, in patients 4 and 5; and two novel mutations, p.H688HfsX and p.Q3147Qfs2X, in patients 6 and 7. These mutations were not present in 100 unrelated healthy Chinese control subjects. The patients' parents were heterozygous carriers of the mutant allele.ConclusionsSeven Chinese patients with AS showed typical ophthalmic features and multiple organ dysfunction. Novel loss of function mutations in the ALMS1 gene are the underlying genetic defects.
| S-EPMC3774572 | biostudies-literature
Project description:Alstrom syndrome is a rare autosomal recessive disorder resulting from an ALMS1 gene mutation. Here, we present the clinical data of a case of an infant diagnosed with Alstrom syndrome through whole-exome sequencing. A 2-month-old male infant was admitted to Sichuan Provincial Maternity and Child Health Care Hospital on 30 May 2019 after "coughing for half a day and dyspnea for 2 hours". He was diagnosed with severe pneumonia, acute congestive heart failure, Grade III cardiac function, acute respiratory failure, and myocarditis. After treatment, he was discharged with a prescription for oral medication. After a 4-month follow-up, the patient's left ventricle exhibited spherical enlargement and a decrease in left ventricular function. The infant's whole-exome sequencing results revealed compound heterozygous mutations in the ALMS1 gene: c.2179dup (p. Y727Lfs*12), a frameshift mutation, that was heterozygous and originated from the mother, while c.11140C>T (p. Q3714*) was a heterozygous nonsense mutation that originated from the father. Both mutations are classified as "category 1-pathogenic mutations" according to the American College of Medical Genetics and Genomics (ACMG) assessment. A novel ALMS1 mutation was identified in this case report, highlighting the importance of genetic testing for the early diagnosis of Alstrom syndrome.
| S-EPMC10345921 | biostudies-literature
Project description:Alström syndrome is a rare multi-systemic disorder with a broad spectrum of symptoms. This syndrome is characterized by childhood retinal degeneration; sensorineural hearing loss; obesity; type 2 diabetes mellitus; cardiomyopathy; systemic fibrosis; and pulmonary, hepatic, and renal failure.A Chinese quartet family with two siblings predominantly affected by cone-rod dystrophy and short stature were recruited. The craniofacial dysmorphism and on-set age-of-cone-rod dystrophy in the proband showed a minor intrafamilial variability. Whole genome sequencing was performed to provide the full spectrum of the two siblings' genetic variations. In this study, we present the patients' clinical features and our interpretation of the whole genome sequencing data. After examining the data, we focus on two compound heterozygous mutations, (c.3902C?>?A, p.S1301X; c.6436C?>?T, p.R2146X) in ALMS1, which are shared by two siblings.We reported a novel ALMS1 mutation. Whole genome sequencing is a powerful tool to provide the full spectrum of genetic variations for heterogeneous disorders such as Alström syndrome.
| S-EPMC5518093 | biostudies-literature
Project description:BACKGROUND:Syndromic dilated cardiomyopathy (DCM) includes a group of complex disorders with a very heterogeneous genetic etiology, leading to delay in definitive diagnosis. Conversely, an early genetic diagnosis is very important in determining the disease course, the prognosis, and may guide personalized treatments and family counseling. METHODS:We analyzed two brothers with a multisystemic disorder, including dilated cardiomyopathy, diabetes, bilateral neurosensorial hearing loss, and optic atrophy, using different genetic approaches, namely mitochondrial DNA sequencing, comparative genomic hybridization-array (a-CGH) and whole exome sequencing (WES). RESULTS:Sequencing of the wide mitochondrial genome revealed, in both brothers, the known homoplasmic variant rs2853826 in the subunit 3 of the NADH dehydrogenase gene (MT-ND3), whose pathogenicity was conflicting. Comparative genomic hybridization-array analysis revealed in both patients and their father two heterozygous deletions in Phosphodiesterase 4d-Interacting Protein (PDE4DIP) and Protocadherin-related 15 (PCDH15) genes, respectively. The use of WES detected a pathogenetic mutation in ALMS1, enabling the definitive diagnosis of Alström syndrome. CONCLUSION:We demonstrated how the diagnosis of a complex heterogeneous disease may be difficult, due to several overlapping manifestations and the possible interaction of more genetic variants that could lead to a more severe and complex phenotype. This paper strongly evidences how genomics is revolutionizing the diagnosis of rare complex disease, representing one of the most essential steps to enable a definitive diagnosis and to establish the etiology for diseases, such as syndromic DCM.
| S-EPMC7336746 | biostudies-literature