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- Dahlqvist, Johanna, et al.
(author)
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Congenital ichthyosis : mutations in ichthyin are associated with specific structural abnormalities in the granular layer of epidermis
- 2007
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In: Journal of Medical Genetics. - : BMJ. - 0022-2593 .- 1468-6244. ; 44:10, s. 615-620
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Journal article (peer-reviewed)abstract
- Background: Autosomal recessive congenital ichthyosis (ARCI) is a heterogeneous group of skin disorders. Several mutant genes have been identified in ARCI, but the association between genotype and phenotype is poorly understood. Methods: To investigate genotype–phenotype correlations in ARCI, we selected 27 patients from 18 families with specific ultrastructural features of the epidermis. The characteristic findings using electron microscopy (EM) were abnormal lamellar bodies and elongated membranes in the stratum granulosum, classified as ARCI EM type III. DNA samples from a subset of affected individuals were screened for homozygous genomic regions, and a candidate gene region was identified on chromosome 5q33. The region coincides with the ichthyin gene, previously reported as mutated in ARCI. Results: Mutation screening of ichthyin revealed missense or splice-site mutations in affected members from 16 of 18 (89%) families with characteristics of ARCI EM type III. In a control group of 18 patients with ARCI without EM findings consistent with type III, we identified one patient homozygous for a missense mutation in ichthyin. Discussion: Our findings indicate a strong association between ultrastructural abnormalities in the granular layer of epidermis and ichthyin mutations. The results also suggest that EM provides a tool for specific diagnosis in a genetically homogenous subgroup of patients with ARCI.
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| 5. |
- Melin, Malin, et al.
(author)
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A founder mutation for ichthyosis prematurity syndrome restricted to 76 kb by haplotype association
- 2006
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In: Journal of Human Genetics. - : Springer Science and Business Media LLC. - 1434-5161 .- 1435-232X. ; 51:10, s. 864-871
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Journal article (peer-reviewed)abstract
- Autosomal recessive congenital ichthyosis (ARCI) is a group of keratinisation disorders that includes the ichthyosis prematurity syndrome (IPS). IPS is rare and almost exclusively present in a restricted region in the middle of Norway and Sweden, which indicates a founder effect for the disorder. We recently reported linkage of IPS to chromosome 9q34, and we present here the subsequent fine-mapping of this region with known and novel microsatellite markers as well as single nucleotide polymorphisms (SNPs). Allelic association, evaluated with Fisher's exact test and P (excess), was used to refine the IPS haplotype to approximately 1.6 Mb. On the basis of the average length of the haplotype in IPS patients, we calculated the age of a founder mutation to approximately 1,900 years. The IPS haplotype contains a core region of 76 kb consisting of four marker alleles shared by 97.7% of the chromosomes associated with IPS. This region spans four known genes, all of which are expressed in mature epidermal cells. We present the results from the analysis of these four genes and their corresponding transcripts in normal and patient-derived samples.
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| 6. |
- Pigg, Maritta, et al.
(author)
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Haplotype association and mutation analysis of the transglutaminase 1 gene for prenatal exclusion of lamellar ichthyosis
- 2000
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In: Prenatal Diagnosis. - 0197-3851 .- 1097-0223. ; 20:2, s. 132-7
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Journal article (peer-reviewed)abstract
- Lamellar ichthyosis (LI) is an autosomal recessive keratinization disorder of the skin. Genetic heterogeneity has been shown for the disease and there is evidence for the involvement of the transglutaminase 1 (TGM1) gene on chromosome 14q11. We have previously identified chromosome 14q11 haplotypes associated with ichthyosis in the Norwegian population. In this paper we describe antenatal exclusion of ichthyosis in two Norwegian families by chromosome 14q11 haplotype association and direct mutation analysis. In one pregnancy, the 11-week old fetus at risk for LI was found to share only one disease-associated haplotype. A subsequent mutation analysis of the TGM1 gene in fetal DNA revealed that the fetus carried a novel 3795A-->T transversion. The affected proband was compound heterozygous for the mutations 3795A-->T and 3239G-->C resulting in an Asp430Val and a Val379Leu, respectively. In another LI family, the 11-week old fetus was found to be heterozygous for the 14q11 haplotype associated with the disease. Subsequent mutation analysis revealed that the fetus was heterozygous for the 2526A-->G transition in the splice site of intron 5 whereas the proband was homozygous for the same mutation. Our results show that haplotyping can be a useful tool for prenatal diagnosis in diseases with genetic heterogeneity.
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| 7. |
- Pigg, Maritta, et al.
(author)
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Strong founder effect for a transglutaminase 1 gene mutation in lamellar ichthyosis and congenital ichthyosiform erythroderma from Norway
- 1998
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In: European Journal of Human Genetics. - 1018-4813 .- 1476-5438. ; 6:6, s. 589-96
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Journal article (peer-reviewed)abstract
- Autosomal recessive congenital ichthyosis (ARCI) is a clinically heterogeneous disorder of keratinisation. It was recently shown that mutations in the transglutaminase 1 (TGM1) gene may be associated with the clinical subtypes lamellar ichthyosis (LI) and non-bullous congenital ichthyosiform erythroderma (CIE). Thirty-six Norwegian families with LI and seven with non-bullous CIE were studied with microsatellite markers linked to the TGMI gene. One common haplotype for two markers was found on 74% of disease associated chromosomes. Three individuals homozygous for the common haplotype, two affected by LI and one affected by CIE, were analysed for mutations in the TGM1 gene. All three patients were found homozygous for a single A to G transition located in the canonical splice acceptor site of intron 5. Probands from the remaining 40 families with LI and CIE were screened for this mutation and the A to G transition was found on 61 out of 72 alleles associated with LI and on 9 out of 15 alleles associated with CIE. These findings suggest a single founder mutation for the majority of patients with LI and CIE in Norway. The 2526A-->G mutation results in the insertion of a guanosine at position 877 (876insG) in the mature cDNA and the frame shift creates a premature termination at codon 293. The mutation was previously observed in one family with a resulting cDNA that included the entire intron 5. These results suggest that the mutation can result in variant transcripts in different individuals.
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| 8. |
- Örlén, Hanna, et al.
(author)
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SPG11 mutations cause Kjellin syndrome, a hereditary spastic paraplegia with thin corpus callosum and central retinal degeneration.
- 2009
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In: American Journal of Medical Genetics. Part B, Neuropsychiatric Genetics. - : Wiley. - 1552-485X .- 1552-4841. ; 150B:7, s. 984-992
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Journal article (peer-reviewed)abstract
- Autosomal recessive hereditary spastic paraplegia (ARHSP) with thin corpus callosum (TCC) is genetically heterogenous and approximately 35% of patients carry mutations in either of the SPG11 or SPG15 genes. Disease onset is during the first three decades of life with spastic paraplegia and mental impairment. Peripheral neuropathy and amyotrophy may occur. Kjellin syndrome is characterized by central retinal degeneration in addition to ARHSP-TCC and the disease is associated with mutations in the SPG15 gene. We identified five patients in four unrelated kindreds with spastic paraplegia and mental impairment. Magnetic resonance imaging revealed TCC, atrophy elsewhere in the brain and increased T2 signal intensity in the periventricular white matter. Probands from the four kindreds were screened for mutations in the SPG11 gene. All patients were found homozygous or compound heterozygous for truncating SPG11 mutations of which four are reported for the first time. Ophthalmological investigations revealed that the four index cases have central retinal degeneration consistent with Kjellin syndrome. PET examinations with N-[11C-methyl]-L-deuterodeprenyl (DED) and fluor-18 2-fluorodeoxyglucose (FDG) were performed in two patients with Kjellin syndrome. We observed a reduced glucose uptake in the thalami, anterior cingulum, and sensorimotor cortex indicating neuronal loss, and an increased DED binding in the thalami and pons which suggests astrogliosis. From our results we extend the SPG11 associated phenotype to comprise also Kjellin syndrome, previously found to be associated with mutations in the SPG15 gene. We anticipate that degeneration of the central retina is a common and previously unrecognized feature in SPG11 related disease.
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| 9. |
- Akram, Talia, et al.
(author)
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Aberrant splicing due to a novel RPS7 variant causes Diamond-Blackfan Anemia associated with spontaneous remission and meningocele
- 2020
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In: International Journal of Hematology. - : Springer Science and Business Media LLC. - 0925-5710 .- 1865-3774. ; 112:6, s. 894-899
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Journal article (peer-reviewed)abstract
- Diamond-Blackfan Anemia (DBA) is a congenital pure red cell aplasia caused by heterozygous variants in ribosomal protein genes. The hematological features associated with DBA are highly variable and non-hematological abnormalities are common. We report herein on an affected mother and her daughter presenting with transfusion-dependent anemia. The mother showed mild physical abnormalities and entered spontaneous remission at age 13 years. Her daughter was born with occipital meningocele. Exome sequencing of DNA from the mother revealed a heterozygous novel splice site variant (NM_001011.4:c.508-3T > G) in the Ribosomal Protein S7 gene (RPS7) inherited by the daughter. Functional analysis of the RPS7 variant expressed from a mini-gene construct revealed that the exon 7 acceptor splice site was replaced by a cryptic splice resulting in a transcript missing 64 bp of exon 7 (p.Val170Serfs*8). Our study confirms a pathogenic effect of a novel RPS7 variant in DBA associated with spontaneous remission in the mother and meningocele in her daughter, thus adding to the genotype-phenotype correlations in DBA.
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| 10. |
- Ali, Zafar, et al.
(author)
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Homozygous GRID2 missense mutation predicts a shift in the D-serine binding domain of GluD2 in a case with generalized brain atrophy and unusual clinical features
- 2017
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In: BMC Medical Genetics. - : Springer Science and Business Media LLC. - 1471-2350. ; 18:1
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Journal article (peer-reviewed)abstract
- BACKGROUND: Spinocerebellar ataxias comprise a large and heterogeneous group of disorders that may present with isolated ataxia, or ataxia in combination with other neurologic or non-neurologic symptoms. Monoallelic or biallelic GRID2 mutations were recently reported in rare cases with cerebellar syndrome and variable degree of ataxia, ocular symptoms, hypotonia and developmental delay.CASE PRESENTATION: We report on a consanguineous family with autosomal recessive childhood onset of slowly progressive cerebellar ataxia and delayed psychomotor development in three siblings. MRI of an adult and affected family member revealed slightly widened cerebral and cerebellar sulci, suggesting generalized brain atrophy, and mild cerebellar atrophy. Using whole exome sequencing we identified a novel homozygous missense variant [c.2128C > T, p.(Arg710Trp)] in GRID2 that segregates with the disease. The missense variant is located in a conserved region encoding the extracellular serine-binding domain of the GluD2 protein and predicts a change in conformation of the protein.CONCLUSION: The widespread supratentorial brain abnormalities, absence of oculomotor symptoms, increased peripheral muscle tone and the novel missense mutation add to the clinical and genetic variability in GRID2 associated cerebellar syndrome. The neuroradiological findings in our family indicate a generalized neurodegenerative process to be taken into account in other families segregating complex clinical features and GRID2 mutations.
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