Dataset Information

Cellular ciliary phenotyping indicates pathogenicity of novel variants in IFT140 and confirms a Mainzer-Saldino syndrome diagnosis.

ABSTRACT:

Background

Mainzer-Saldino syndrome (MZSDS) is a skeletal ciliopathy and part of the short-rib thoracic dysplasia (SRTD) group of ciliary disorders. The main characteristics of MZSDS are short limbs, mild narrow thorax, blindness, and renal failure. Thus far, variants in two genes are associated with MZSDS: IFT140, and IFT172. In this study, we describe a 1-year-old girl presenting with mild skeletal abnormalities, Leber congenital amaurosis, and bilateral hearing difficulties. For establishing an accurate diagnosis, we combined clinical, molecular, and functional analyses.

Methods

We performed diagnostic whole-exome sequencing (WES) analysis to determine the genetic cause of the disease and analyzed two gene panels, containing all currently known genes in vision disorders, and in hearing impairment. Upon detection of the likely causative variants, ciliary phenotyping was performed in patient urine-derived renal epithelial cells (URECs) and rescue experiments were performed in CRISPR/Cas9-derived Ift140 knock out cells to determine the pathogenicity of the detected variants in vitro. Cilium morphology, cilium length, and intraflagellar transport (IFT) were evaluated by immunocytochemistry.

Results

Diagnostic WES revealed two novel compound heterozygous variants in IFT140, encoding IFT140. Thorough investigation of WES data did not reveal any variants in candidate genes associated with hearing impairment. Patient-derived URECs revealed an accumulation of IFT-B protein IFT88 at the ciliary tip in 41% of the cells indicative of impaired retrograde IFT, while this was absent in cilia from control URECs. Furthermore, transfection of CRISPR/Cas9-derived Ift140 knock out cells with an IFT140 construct containing the patient mutation p.Tyr923Asp resulted in a significantly higher percentage of IFT88 tip accumulation than transfection with the wild-type IFT140 construct.

Conclusions

By combining the clinical, genetic, and functional data from this study, we could conclude that the patient has SRTD9, also called Mainzer-Saldino syndrome, caused by variants in IFT140. We suggest the possibility that variants in IFT140 may underlie hearing impairment. Moreover, we show that urine provides an excellent source to obtain patient-derived cells in a non-invasive manner to study the pathogenicity of variants detected by genetic testing.

SUBMITTER: Oud MM

PROVIDER: S-EPMC6247778 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Cellular ciliary phenotyping indicates pathogenicity of novel variants in <i>IFT140</i> and confirms a Mainzer-Saldino syndrome diagnosis.

Oud Machteld M MM Latour Brooke L BL Bakey Zeineb Z Letteboer Stef J SJ Lugtenberg Dorien D Wu Ka Man KM Cornelissen Elisabeth A M EAM Yntema Helger G HG Schmidts Miriam M Roepman Ronald R Bongers Ernie M H F EMHF

Cilia 20180223

<h4>Background</h4>Mainzer-Saldino syndrome (MZSDS) is a skeletal ciliopathy and part of the short-rib thoracic dysplasia (SRTD) group of ciliary disorders. The main characteristics of MZSDS are short limbs, mild narrow thorax, blindness, and renal failure. Thus far, variants in two genes are associated with MZSDS: <i>IFT140,</i> and <i>IFT172</i>. In this study, we describe a 1-year-old girl presenting with mild skeletal abnormalities, Leber congenital amaurosis, and bilateral hearing difficult ...[more]

PMID: 30479745

Similar Datasets

Project description:The ciliopathies represent an umbrella group of >50 clinical entities that share both clinical features and molecular etiology underscored by structural and functional defects of the primary cilium. Despite the advances in gene discovery, this group of entities continues to pose a diagnostic challenge, in part due to significant genetic and phenotypic heterogeneity and variability. We consulted a pediatric case from asymptomatic, non-consanguineous parents who presented as a suspected ciliopathy due to a constellation of retinal, renal, and skeletal findings.Although clinical panel sequencing of genes implicated in nephrotic syndromes yielded no likely causal mutation, an oligo-SNP microarray identified a ~20-Mb region of homozygosity, with no altered gene dosage, on chromosome 16p13. Intersection of the proband's phenotypes with known disease genes within the homozygous region yielded a single candidate, IFT140, encoding a retrograde intraflagellar transport protein implicated previously in several ciliopathies, including the phenotypically overlapping Mainzer-Saldino syndrome (MZSDS). Sanger sequencing yielded a maternally inherited homozygous c.634G>A; p.Gly212Arg mutation altering the exon 6 splice donor site. Functional studies in cells from the proband showed that the locus produced two transcripts: a majority message containing a mis-splicing event that caused a premature termination codon and a minority message homozygous for the p.Gly212Arg allele. Zebrafish in vivo complementation studies of the latter transcript demonstrated a loss of function effect. Finally, we conducted post-hoc trio-based whole exome sequencing studies to (a) test the possibility of other causal loci in the proband and (b) explain the Mendelian error of segregation for the IFT140 mutation. We show that the proband harbors a chromosome 16 maternal heterodisomy, with segmental isodisomy at 16p13, likely due to a meiosis I error in the maternal gamete.Using clinical phenotyping combined with research-based genetic and functional studies, we have characterized a recurrent IFT140 mutation in the proband; together, these data are consistent with MZSDS. Additionally, we report a rare instance of a uniparental isodisomy unmasking a deleterious mutation to cause a ciliary disorder.

Project description:Backgroundartificial intelligence (AI) for cellular phenotyping diagnosis of nasal polyps by whole-slide imaging (WSI) is lacking. We aim to establish an AI chronic rhinosinusitis evaluation platform 2.0 (AICEP 2.0) to obtain the proportion of inflammatory cells for cellular phenotyping diagnosis of nasal polyps and to explore the clinical significance of different phenotypes of nasal polyps on the WSI.Methodsa total of 453 patients were enrolled in our study. For the development of AICEP 2.0, 179 patients (WSIs) were obtained from the Third Affiliated Hospital of Sun Yat-Sen University (3HSYSU) from January 2008 to December 2018. A total of 24,625 patches were automatically extracted from the regions of interest under a 400× HPF by Openslide and the number of inflammatory cells in these patches was counted by two pathologists. For the application of AICEP 2.0 in a prospective cohort, 158 patients aged 14-70 years old with chronic rhinosinusitis with nasal polyps (CRSwNP) who had undergone endoscopic sinus surgery at 3HSYSU from June 2020 to December 2020 were included for preoperative demographic characteristics. For the application of AICEP 2.0 in a retrospective cohort, 116 patients with CRSwNP who had undergone endoscopic sinus surgery from May 2016 to June 2017 were enrolled for the recurrence rate. The proportion of inflammatory cells of these patients on WSI was calculated by our AICEP 2.0.Findingsfor AICEP 2.0, the mean absolute errors of the ratios of eosinophils, lymphocytes, neutrophils, and plasma cells were 1.64%, 2.13%, 1.06%, and 1.22%, respectively. The four phenotypes of nasal polyps were significantly different in clinical characteristics (including asthma, itching, sneezing, total IgE, peripheral eosinophils%, tissue eosinophils%, tissue neutrophils%, tissue lymphocytes%, tissue plasma cells%, and recurrence rate; P <0.05), but there were no significant differences in age distribution, onset time, total VAS score, Lund-Kennedy score, or Lund-Mackay score. The percentage of peripheral eosinophils was positively correlated with the percentage of tissue eosinophils (r = 0.560, P <0.001) and negatively correlated with tissue lymphocytes% (r = -0.489, P <0.001), tissue neutrophils% (r = -0.225, P = 0.005), and tissue plasma cells% (r = -0.266, P = 0.001) in WSIs.

Project description:The goal of this project is to understand the etiology and pathology of host-pathogen interaction using high-throughput cellular phenotyping. By combining the expertise in pathogen biology, informatics and stem cell biology across the institute, this project will use targeted genetic modification in mouse embryonic stem cells to identify functions of host genes in innate immunity. We will also explore the biology of mouse embryonic stem cells and their differentiation into immune competent cells. To this end we will generate homozygous and inducible knockout lines in mouse embryonic stem cells, which will be differentiated into immune competent cells, such as macrophages or dendritic cells. These will be subjected to a panel of immune challenge and stimulation assays to characterise the functions of the disrupted genes. To identify new functions for mammalian genes in innate immunity we will:\Generate a panel of homozygous inducible gene knockout mouse ES cell lines working from a list of ca. 80 candidate genes (MGP phenotyping and GWAS hits). \Scale up differentiation protocols for immune challenge and stimulation assays.\Benchmark in vitro differentiated ES cell models against primary immune cells from selected MGP mouse lines and eventually against human iPS cells.\Screen a panel of 30 genetically modified cell lines in immunological challenge and stimulation assays, defining phenotypes at the cellular level by high content imaging, biochemically by assaying cytokine production, and at the molecular level by transcriptome analysis.\Define novel gene functions in innate immunity through network analysis of gene expression data from all challenged cell lines.\In the longer term scale up the production and phenotyping of genetically modified cell lines (mouse or human as appropriate).This data is part of a pre-publication release. For information on the proper use of pre-publication data shared by the Wellcome Trust Sanger Institute (including details of any publication moratoria), please see http://www.sanger.ac.uk/datasharing/

Project description:Ciliopathies are rare congenital disorders, caused by defects in the cilium, that cover a broad clinical spectrum. A subgroup of ciliopathies showing significant phenotypic overlap are known as skeletal ciliopathies and include Jeune asphyxiating thoracic dysplasia (JATD), Mainzer-Saldino syndrome (MZSDS), cranioectodermal dysplasia (CED), and short-rib polydactyly (SRP). Ciliopathies are heterogeneous disorders with >187 associated genes, of which some genes are described to cause more than one ciliopathy phenotype. Both the clinical and molecular overlap make accurate diagnosing of these disorders challenging. We describe two unrelated Polish patients presenting with a skeletal ciliopathy who share the same compound heterozygous variants in IFT140 (NM_014,714.4) r.2765_2768del; p.(Tyr923Leufs*28) and exon 27-30 duplication; p.(Tyr1152_Thr1394dup). Apart from overlapping clinical symptoms the patients also show phenotypic differences; patient 1 showed more resemblance to a Mainzer-Saldino syndrome (MZSDS) phenotype, while patient 2 was more similar to the phenotype of cranioectodermal dysplasia (CED). In addition, functional testing in patient-derived fibroblasts revealed a distinct cilium phenotyps for each patient, and strikingly, the cilium phenotype of CED-like patient 2 resembled that of known CED patients. Besides two variants in IFT140, in depth exome analysis of ciliopathy associated genes revealed a likely-pathogenic heterozygous variant in INTU for patient 2 that possibly affects the same IFT-A complex to which IFT140 belongs and thereby could add to the phenotype of patient 2. Taken together, by combining genetic data, functional test results, and clinical findings we were able to accurately diagnose patient 1 with "IFT140-related ciliopathy with MZSDS-like features" and patient 2 with "IFT140-related ciliopathy with CED-like features". This study emphasizes that identical variants in one ciliopathy associated gene can lead to a variable ciliopathy phenotype and that an in depth and integrated analysis of clinical, molecular and functional data is necessary to accurately diagnose ciliopathy patients.