A case of Bardet-Biedl syndrome caused by a recurrent variant in BBS12: A case report
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ABSTRACT:
SUBMITTER: Focsa I
PROVIDER: S-EPMC8567465 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:IntroductionBardet-Biedl syndrome (BBS) is a rare genetic syndrome caused by a mutation in one of 26 different genes responsible for normal structure and/or function of primary cilia. The syndrome is characterized by multiorgan involvement with gradual onset of occurrence of clinical signs and symptoms resulting in great phenotypic variability and what is more important, often difficulties with establishing the timely diagnosis.Case reportWe report a case of a one family with three members with BBS caused by a very rare mutation, a compound heterozygosity in BB12 gene. Even though all three patients have the same type of mutation, they express a significant diversity in clinical expression as well as renal impairment.ConclusionThis is a case report of a rare clinical syndrome caused by a very rare genetic mutation and it emphasizes the importance of genetic analysis in the timely diagnosis of oligosymptomatic patients with BBS, in order to possibly prevent long-term complications.
| S-EPMC10352915 | biostudies-literature
Project description:Bardet-Biedl syndrome (BBS) is a rare autosomal recessive disorder of the cilia, often resulting in a phenotype of obesity, rod-cone dystrophy, a variable degree of intellectual disability, polydactyly, renal problems, and/or hypogonadism in males or genital abnormalities in females. We here report the case of an 11-year-old girl who presented with postaxial polydactyly, retinal dystrophy, and childhood obesity, suggesting Bardet-Biedl syndrome. She had no renal problems, developmental delay, or intellectual disability. Genetic testing revealed compound heterozygous variants in the IFT74 gene (c.371_372del p.Gln124Argfs*9 and c.16850-1G>T p.?). We here report the second patient with Bardet-Biedl syndrome due to biallelic IFT74 variants. Both patients have obesity, polydactyly, retinal dystrophy, and no renal abnormalities. The present case however, has normal intellect, whereas the other patient has intellectual disability. We hereby confirm IFT74 as a BBS gene and encourage diagnostic genetic testing laboratories to add IFT74 to their BBS gene panels.
| S-EPMC7316806 | biostudies-literature
Project description:Bardet-Biedl syndrome (BBS) is a rare autosomal recessive ciliopathy characterised by retinal dystrophy, obesity, post-axial polydactyly, renal dysfunction, learning difficulties and hypogonadism. Many associated minor features can be helpful in making a diagnosis and are important in the clinical management of BBS. The diagnosis is based on clinical findings and can be confirmed by sequencing of known disease-causing genes in 80% of patients. BBS genes encode proteins that localise to the cilia and basal body and are involved in cilia biogenesis and function. Mutations lead to defective cilia accounting in part for the pleiotropic effects observed in BBS. We provide an overview of BBS including the clinical findings, current understanding of cilia biology, and a practical approach to diagnosis, genetic counselling and up-to-date management.
| S-EPMC3522196 | biostudies-other
Project description:Bardet-Biedl syndrome (BBS), is an emblematic ciliopathy hallmarked by pleiotropy, phenotype variability, and extensive genetic heterogeneity. BBS is a rare (~1/140,000 to ~1/160,000 in Europe) autosomal recessive pediatric disorder characterized by retinal degeneration, truncal obesity, polydactyly, cognitive impairment, renal dysfunction, and hypogonadism. Twenty-eight genes involved in ciliary structure or function have been implicated in BBS, and explain the molecular basis for ~75%-80% of individuals. To investigate the mutational spectrum of BBS in Romania, we ascertained a cohort of 24 individuals in 23 families. Following informed consent, we performed proband exome sequencing (ES). We detected 17 different putative disease-causing single nucleotide variants or small insertion-deletions and two pathogenic exon disruptive copy number variants in known BBS genes in 17 pedigrees. The most frequently impacted genes were BBS12 (35%), followed by BBS4, BBS7, and BBS10 (9% each) and BBS1, BBS2, and BBS5 (4% each). Homozygous BBS12 p.Arg355* variants were present in seven pedigrees of both Eastern European and Romani origin. Our data show that although the diagnostic rate of BBS in Romania is likely consistent with other worldwide cohorts (74%), we observed a unique distribution of causal BBS genes, including overrepresentation of BBS12 due to a recurrent nonsense variant, that has implications for regional diagnostics.
| S-EPMC10524726 | biostudies-literature
Project description:Bardet-Biedl syndrome (BBS) is a rare genetic disorder that belongs to the group of ciliopathies, defined as diseases caused by defects in cilia structure and/or function. The six diagnostic features considered for this syndrome include retinal dystrophy, obesity, polydactyly, cognitive impairment and renal and urogenital anomalies. Furthermore, three of the 21 genes currently known to be involved in BBS encode chaperonin-like proteins (MKKS/BBS6, BBS10, and BBS12), so BBS can be also considered a member of the growing group of chaperonopathies. Remarkably, up to 50% of clinically-diagnosed BBS families can harbor disease-causing variants in these three genes, which highlights the importance of chaperone defects as pathogenic factors even for genetically heterogeneous syndromes such as BBS. In addition, it is interesting to note that BBS families with deleterious variants in MKKS/BBS6, BBS10 or BBS12 genes generally display more severe phenotypes than families with changes in other BBS genes. The chaperonin-like BBS proteins have structural homology to the CCT family of group II chaperonins, although they are believed to conserve neither the ATP-dependent folding activity of canonical CCT chaperonins nor the ability to form CCT-like oligomeric complexes. Thus, they play an important role in the initial steps of assembly of the BBSome, which is a multiprotein complex essential for mediating the ciliary trafficking activity. In this review, we present a comprehensive review of those genetic, functional and evolutionary aspects concerning chaperonin-like BBS proteins, trying to provide a new perspective that expands the classical conception of BBS only from a ciliary point of view.
| S-EPMC5534436 | biostudies-literature
Project description:Bardet-Biedl Syndrome (BBS) is an autosomal recessive systemic disorder characterized by retinitis pigmentosa, polydactyly, obesity, intellectual disability, renal impairments, and hypogonadism. The purpose of this study was to determine the ocular characteristics of a boy with BBS caused by a novel homozygous variant in the ARL6 (alternative named BBS3) gene who had been originally diagnosed with retinitis punctata albescens. This was an observational case study. The patient underwent ophthalmological examinations, electroretinography, and genetic analyses using whole-exome sequencing. A 7-year-old boy was examined in our hospital with complaints of a progressive reduction of his visual acuity and night blindness in both eyes. There was no family history of eye diseases and no consanguineous marriage. Fundus examinations showed numerous white spots in the deep retina and retinal pigment epithelium. Fundus autofluorescence showed hypofluorescence consistent with these spots. Both the scotopic and photopic components of the full-field electroretinographies were non-detectable. Based on these clinical findings, this boy was suspected to have retinitis punctata albescens. Subsequent genetic testing using whole-exome sequencing revealed a novel homozygous variants in the ARL6/BBS3 gene (NM_001278293.3:c.528G>A, (p.Trp176Ter)). A systemic examination by the pediatric department revealed that this boy had a history of a surgical excision of polydactyly on his left foot when he was born, and that he was mildly obese. There were no prominent intellectual or gonadal dysfunctions, no craniofacial or dental abnormalities, no congenital heart disease, and no hearing impairment. He was then clinically and genetically diagnosed with BBS. In children with night blindness and progressive visual dysfunction, it is important for ophthalmologists to consult clinical geneticists and pediatricians to rule out the possibility of systemic diseases such as BBS.
| S-EPMC9771268 | biostudies-literature
Project description:The Bardet-Biedl syndrome (BBS) is a significant genetic cause of chronic and end-stage renal failure in children. Despite being a relatively rare recessive condition, BBS has come to prominence during the past few years owing to revelations of primary cilia dysfunction underlying pathogenesis. The study of this multi-system disorder, which includes obesity, cognitive impairment, genito-urinary tract malformations and limb deformities, is beginning to reveal insights into several aspects of mammalian development and organogenesis. Involvement of BBS proteins in disparate pathways such as the non-canonical Wnt and Sonic Hedgehog pathways is highlighting their interplay in disease pathogenesis. Here we review the recent developments in this emerging field, with the emphasis on the renal component of the syndrome and potential future directions.
| S-EPMC6904379 | biostudies-literature
Project description:The aim of this study was to explore kidney failure (KF) in Bardet-Biedl syndrome (BBS), focusing on high-risk gene variants, demographics, and morbidity. We employed the Clinical Registry Investigating BBS (CRIBBS) to identify 44 (7.2%) individuals with KF out of 607 subjects. Molecularly confirmed BBS was identified in 37 KF subjects and 364 CRIBBS registrants. KF was concomitant with recessive causal variants in 12 genes, with BBS10 the most predominant causal gene (26.6%), while disease penetrance was highest in SDCCAG8 (100%). Two truncating variants were present in 67.6% of KF cases. KF incidence was increased in genes not belonging to the BBSome or chaperonin-like genes (p < 0.001), including TTC21B, a new candidate BBS gene. Median age of KF was 12.5 years, with the vast majority of KF occurring by 30 years (86.3%). Females were disproportionately affected (77.3%). Diverse uropathies were identified, but were not more common in the KF group (p = 0.672). Kidney failure was evident in 11 of 15 (73.3%) deaths outside infancy. We conclude that KF poses a significant risk for premature morbidity in BBS. Risk factors for KF include female sex, truncating variants, and genes other than BBSome/chaperonin-like genes highlighting the value of comprehensive genetic investigation.
| S-EPMC9311438 | biostudies-literature
Project description:Bardet-Biedl syndrome (BBS) is a rare disorder with a frequency of 1:1,60,000. The disease is inherited in an autosomal recessive manner. Less than 15 cases have been reported from India. We present a case of Bardet-Biedl syndrome presenting to the medical emergency with acute breathlessness because of de-compensated renal failure and salient features such as marked polydactyly, central obesity, retinitis pigmentosa, end-stage renal diseases, and mental retardation. Genetic study showed that the patient had BBS genetic variant 9 (MIM#615896), VUS variant. The patient was primarily treated for end-stage chronic renal failure with hemodialysis. We are reporting this case for its rarity and the presence of a novel genetic variant of an unidentified significance as per genome mapping. BBS is often not diagnosed at all or diagnosed late until end-stage renal failure sets in. Timely diagnosis might not help treat the condition but surely improve the quality of life for the patient.
| S-EPMC9872935 | biostudies-literature
Project description:Bardet-Biedl syndrome (BBS) is a pleiotropic and multisystemic disorder characterized by rod-cone dystrophy, polydactyly, learning difficulties, renal abnormalities, obesity and hypogonadism. This disorder is genetically heterogeneous. Until now, a total of nineteen genes have been identified for BBS whose mutations explain more than 80% of diagnosed cases. Recently, the development of next generation sequencing (NGS) technology has accelerated mutation screening of target genes, resulting in lower cost and less time consumption. Here, we screened the most common BBS genes (BBS1-BBS13) using NGS in an Iranian family of a proposita displaying symptoms of BBS. Among the 18 mutations identified in the proposita, one (BBS12 c.56T>G and BBS12 c.1156C>T) was novel. This compound heterozygosity was confirmed by Sanger sequencing in the proposita and her parents. Although our data were presented as a case report, however, we suggest a new probable genetic mechanism other than the conventional autosomal recessive inheritance of BBS. Additionally, given that in some Iranian provinces, like Khuzestan, consanguineous marriages are common, designing mutational panels for genetic diseases is strongly recommended, especially for those with an autosomal recessive inheritance pattern.
| S-EPMC5893301 | biostudies-literature