| 1. |
- Lindstrand, Anna, et al.
(författare)
-
From cytogenetics to cytogenomics : whole-genome sequencing as a first-line test comprehensively captures the diverse spectrum of disease-causing genetic variation underlying intellectual disability
- 2019
-
Ingår i: Genome Medicine. - : BMC. - 1756-994X .- 1756-994X. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- BackgroundSince different types of genetic variants, from single nucleotide variants (SNVs) to large chromosomal rearrangements, underlie intellectual disability, we evaluated the use of whole-genome sequencing (WGS) rather than chromosomal microarray analysis (CMA) as a first-line genetic diagnostic test.MethodsWe analyzed three cohorts with short-read WGS: (i) a retrospective cohort with validated copy number variants (CNVs) (cohort 1, n=68), (ii) individuals referred for monogenic multi-gene panels (cohort 2, n=156), and (iii) 100 prospective, consecutive cases referred to our center for CMA (cohort 3). Bioinformatic tools developed include FindSV, SVDB, Rhocall, Rhoviz, and vcf2cytosure.ResultsFirst, we validated our structural variant (SV)-calling pipeline on cohort 1, consisting of three trisomies and 79 deletions and duplications with a median size of 850kb (min 500bp, max 155Mb). All variants were detected. Second, we utilized the same pipeline in cohort 2 and analyzed with monogenic WGS panels, increasing the diagnostic yield to 8%. Next, cohort 3 was analyzed by both CMA and WGS. The WGS data was processed for large (>10kb) SVs genome-wide and for exonic SVs and SNVs in a panel of 887 genes linked to intellectual disability as well as genes matched to patient-specific Human Phenotype Ontology (HPO) phenotypes. This yielded a total of 25 pathogenic variants (SNVs or SVs), of which 12 were detected by CMA as well. We also applied short tandem repeat (STR) expansion detection and discovered one pathologic expansion in ATXN7. Finally, a case of Prader-Willi syndrome with uniparental disomy (UPD) was validated in the WGS data.Important positional information was obtained in all cohorts. Remarkably, 7% of the analyzed cases harbored complex structural variants, as exemplified by a ring chromosome and two duplications found to be an insertional translocation and part of a cryptic unbalanced translocation, respectively.ConclusionThe overall diagnostic rate of 27% was more than doubled compared to clinical microarray (12%). Using WGS, we detected a wide range of SVs with high accuracy. Since the WGS data also allowed for analysis of SNVs, UPD, and STRs, it represents a powerful comprehensive genetic test in a clinical diagnostic laboratory setting.
|
|
| 2. |
|
|
| 3. |
- Tham, Emma, et al.
(författare)
-
A novel phenotype in N-glycosylation disorders: Gillessen-Kaesbach-Nishimura skeletal dysplasia due to pathogenic variants in ALG9.
- 2015
-
Ingår i: European Journal of Human Genetics. - : Springer Science and Business Media LLC. - 1476-5438 .- 1018-4813.
-
Tidskriftsartikel (refereegranskat)abstract
- A rare lethal autosomal recessive syndrome with skeletal dysplasia, polycystic kidneys and multiple malformations was first described by Gillessen-Kaesbach et al and subsequently by Nishimura et al. The skeletal features uniformly comprise a round pelvis, mesomelic shortening of the upper limbs and defective ossification of the cervical spine. We studied two unrelated families including three affected fetuses with Gillessen-Kaesbach-Nishimura syndrome using whole-exome and Sanger sequencing, comparative genome hybridization and homozygosity mapping. All affected patients were shown to have a novel homozygous splice variant NM_024740.2: c.1173+2T>A in the ALG9 gene, encoding alpha-1,2-mannosyltransferase, involved in the formation of the lipid-linked oligosaccharide precursor of N-glycosylation. RNA analysis demonstrated skipping of exon 10, leading to shorter RNA. Mass spectrometric analysis showed an increase in monoglycosylated transferrin as compared with control tissues, confirming that this is a congenital disorder of glycosylation (CDG). Only three liveborn children with ALG9-CDG have been previously reported, all with missense variants. All three suffered from intellectual disability, muscular hypotonia, microcephaly and renal cysts, but none had skeletal dysplasia. Our study shows that some pathogenic variants in ALG9 can present as a lethal skeletal dysplasia with visceral malformations as the most severe phenotype. The skeletal features overlap with that previously reported for ALG3- and ALG12-CDG, suggesting that this subset of glycosylation disorders constitutes a new diagnostic group of skeletal dysplasias.European Journal of Human Genetics advance online publication, 13 May 2015; doi:10.1038/ejhg.2015.91.
|
|
| 4. |
|
|
| 5. |
- Krýsl, David, et al.
(författare)
-
Stereoelectroencephalography - a safe and effective procedure for epilepsy surgery evaluation : Stereo-EEG – en effektiv metod för att utreda svårbehandlad epilepsi.
- 2021
-
Ingår i: Lakartidningen. - 1652-7518. ; 118
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we report our experiences from the first 30 patients investigated with stereoelectroencephalography (SEEG) at Sahlgrenska University Hospital, Gothenburg, Sweden. Clinical, neurophysiological, and imaging data were reviewed. Twelve children and 18 adults with drug-resistant epilepsy underwent 33 SEEG procedures. 53% of the patients had normal brain MRI. In total, 347 SEEG electrodes were implanted (median 12 per patient). Twenty patients subsequently had resective surgery based on SEEG findings. Focal cortical dysplasia was found in all cases. In 45% of the patients, vicinity of eloquent cortex limited resections. Epilepsy surgery based on SEEG resulted in seizure freedom in 58% of the cases. Minor complications were seen in eight patients, all of which resolved without sequelae. No major complications were seen. SEEG is a safe and effective method to delineate cortical areas involved in seizure generation.
|
|
| 6. |
- Kvarnung, Malin, et al.
(författare)
-
Ataxia in Patients With Bi-Allelic NFASC Mutations and Absence of Full-Length NF186
- 2019
-
Ingår i: Frontiers in Genetics. - : Frontiers Media SA. - 1664-8021. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- The etiology of hereditary ataxia syndromes is heterogeneous, and the mechanisms underlying these disorders are often unknown. Here, we utilized exome sequencing in two siblings with progressive ataxia and muscular weakness and identified a novel homozygous splice mutation (c.3020-1G > A) in neurofascin (NFASC). In RNA extracted from fibroblasts, we showed that the mutation resulted in inframe skipping of exon 26, with a deprived expression of the full-length transcript that corresponds to NFASC isoform NF186. To further investigate the disease mechanisms, we reprogrammed fibroblasts from one affected sibling to induced pluripotent stem cells, directed them to neuroepithelial stem cells and finally differentiated to neurons. In early neurogenesis, differentiating cells with selective depletion of the NF186 isoform showed significantly reduced neurite outgrowth as well as fewer emerging neurites. Furthermore, whole-cell patch-clamp recordings of patient-derived neuronal cells revealed a lower threshold for openings, indicating altered Na+ channel kinetics, suggesting a lower threshold for openings as compared to neuronal cells without the NFASC mutation. Taken together, our results suggest that loss of the full-length NFASC isoform NF186 causes perturbed neurogenesis and impaired neuronal biophysical properties resulting in a novel early-onset autosomal recessive ataxia syndrome.
|
|
| 7. |
- Lindstrand, Anna, et al.
(författare)
-
Genome sequencing is a sensitive first-line test to diagnose individuals with intellectual disability
- 2022
-
Ingår i: Genetics in Medicine. - : ELSEVIER SCIENCE INC. - 1098-3600 .- 1530-0366. ; 24:11, s. 2296-2307
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: Individuals with intellectual disability (ID) and/or neurodevelopment disorders (NDDs) are currently investigated with several different approaches in clinical genetic diagnostics. Methods: We compared the results from 3 diagnostic pipelines in patients with ID/NDD: genome sequencing (GS) first (N = 100), GS as a secondary test (N = 129), or chromosomal microarray (CMA) with or without FMR1 analysis (N = 421). Results: The diagnostic yield was 35% (GS -first), 26% (GS as a secondary test), and 11% (CMA/FMR1). Notably, the age of diagnosis was delayed by 1 year when GS was performed as a secondary test and the cost per diagnosed individual was 36% lower with GS first than with CMA/FMR1. Furthermore, 91% of those with a negative result after CMA/FMR1 analysis (338 individuals) have not yet been referred for additional genetic testing and remain undiagnosed. Conclusion: Our findings strongly suggest that genome analysis outperforms other testing strategies and should replace traditional CMA and FMR1 analysis as a first-line genetic test in individuals with ID/NDD. GS is a sensitive, time-and cost-effective method that results in a confirmed molecular diagnosis in 35% of all referred patients. (c) 2022 The Authors. Published by Elsevier Inc. on behalf of American College of Medical Genetics and Genomics. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
|
|
| 8. |
- Magnusson, Måns, et al.
(författare)
-
Loqusdb : added value of an observations database of local genomic variation
- 2020
-
Ingår i: BMC Bioinformatics. - : Springer Nature. - 1471-2105. ; 21:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background Exome and genome sequencing is becoming the method of choice for rare disease diagnostics. One of the key challenges remaining is distinguishing the disease causing variants from the benign background variation. After analysis and annotation of the sequencing data there are typically thousands of candidate variants requiring further investigation. One of the most effective and least biased ways to reduce this number is to assess the rarity of a variant in any population. Currently, there are a number of reliable sources of information for major population frequencies when considering single nucleotide variants (SNVs) and small insertion and deletions (INDELs), with gnomAD as the most prominent public resource available. However, local variation or frequencies in sub-populations may be underrepresented in these public resources. In contrast, for structural variation (SV), the background frequency in the general population is more or less unknown mostly due to challenges in calling SVs in a consistent way. Keeping track of local variation is one way to overcome these problems and significantly reduce the number of potential disease causing variants retained for manual inspection, both for SNVs and SVs. Results Here, we present loqusdb, a tool to solve the challenge of keeping track of any type of variant observations from genome sequencing data. Loqusdb was designed to handle a large flow of samples and unlike other solutions, samples can be added continuously to the database without rebuilding it, facilitating improvements and additions. We assessed the added value of a local observations database using 98 samples annotated with information from a background of 888 unrelated individuals. Conclusions We show both how powerful SV analysis can be when filtering for population frequencies and how the number of apparently rare SNVs/INDELs can be reduced by adding local population information even after annotating the data with other large frequency databases, such as gnomAD. In conclusion, we show that a local frequency database is an attractive, and a necessary addition to the publicly available databases that facilitate the analysis of exome and genome data in a clinical setting.
|
|
| 9. |
- Rasi, Chiara, et al.
(författare)
-
PatientMatcher : A customizable Python-based open-source tool for matching undiagnosed rare disease patients via the Matchmaker Exchange network
- 2022
-
Ingår i: Human Mutation. - : Wiley. - 1059-7794 .- 1098-1004. ; 43:6, s. 708-716
-
Tidskriftsartikel (refereegranskat)abstract
- The amount of data available from genomic medicine has revolutionized the approach to identify the determinants underlying many rare diseases. The task of confirming a genotype–phenotype causality for a patient affected with a rare genetic disease is often challenging. In this context, the establishment of the Matchmaker Exchange (MME) network has assumed a pivotal role in bridging heterogeneous patient information stored on different medical and research servers. MME has made it possible to solve rare disease cases by “matching” the genotypic and phenotypic characteristics of a patient of interest with patient data available at other clinical facilities participating in the network. Here, we present PatientMatcher (https://github.com/Clinical-Genomics/patientMatcher), an open-source Python and MongoDB-based software solution developed by Clinical Genomics facility at the Science for Life Laboratory in Stockholm. PatientMatcher is designed as a standalone MME server, but can easily communicate via REST API with external applications managing genetic analyses and patient data. The MME node is being implemented in clinical routine in collaboration with the Genomic Medicine Center Karolinska at the Karolinska University Hospital. PatientMatcher is written to implement the MME API and provides several customizable settings, including a custom-fit similarity score algorithm and adjustable matching results notifications.
|
|
| 10. |
- Schuy, Jakob, et al.
(författare)
-
Partial Monosomy 21 Mirrors Gene Expression of Trisomy 21 in a Patient-Derived Neuroepithelial Stem Cell Model
- 2022
-
Ingår i: Frontiers in Genetics. - : Frontiers Media SA. - 1664-8021. ; 12
-
Tidskriftsartikel (refereegranskat)abstract
- Induced pluripotent stem cells (iPSCs) from patients are an attractive disease model to study tissues with poor accessibility such as the brain. Using this approach, we and others have shown that trisomy 21 results in genome-wide transcriptional dysregulations. The effects of loss of genes on chromosome 21 is much less characterized. Here, we use patient-derived neural cells from an individual with neurodevelopmental delay and a ring chromosome 21 with two deletions spanning 3.8 Mb at the terminal end of 21q22.3, containing 60 protein-coding genes. To investigate the molecular perturbations of the partial monosomy on neural cells, we established patient-derived iPSCs from fibroblasts retaining the ring chromosome 21, and we then induced iPSCs into neuroepithelial stem cells. RNA-Seq analysis of NESCs with the ring chromosome revealed downregulation of 18 genes within the deleted region together with global transcriptomic dysregulations when compared to euploid NESCs. Since the deletions on chromosome 21 represent a genetic “contrary” to trisomy of the corresponding region, we further compared the dysregulated transcriptomic profile in with that of two NESC lines with trisomy 21. The analysis revealed opposed expression changes for 23 genes on chromosome 21 as well as 149 non-chromosome 21 genes. Taken together, our results bring insights into the effects on the global and chromosome 21 specific gene expression from a partial monosomy of chromosome 21qter during early neuronal differentiation.
|
|
