Marianne Schwartz

Alzheimer disease-like clinical phenotype in a family with FTDP-17 caused by a MAPT R406W mutation.

We report clinical, molecular, neuroimaging and neuropathological features of a Danish family with autosomal dominant inherited dementia, a clinical phenotype resembling Alzheimer’s disease and a pathogenic mutation (R406W) in the microtubule associated protein tau (MAPT) gene. Pre‐symptomatic and affected family members underwent multidisciplinary (clinical, molecular, neuroimaging and neuropathological) examinations. Treatment with memantine in a family member with early symptoms, based on the clinical phenotype and the lack of specific treatment, appears to stabilize the disease course and increase the glucose metabolism in cortical and subcortical areas, as determined by serial [F18]FDG‐PET scanning before and after initiation of treatment. Neuropathological examination of a second affected and mutation‐positive family member showed moderate atrophy of the temporal lobes including the hippocampi. Microscopy revealed abundant numbers of tau‐positive neurofibrillary tangles in all cortical areas and in some brainstem nuclei corresponding to a diagnosis of frontotemporal lobe degeneration on the basis of a MAPT mutation. The clinical and genetic heterogeneity of autosomal dominant inherited dementia must be taken into account in the genetic counselling and genetic testing of families with autosomal dominantly inherited dementia in general.

A novel missense mutation in SUCLG1 associated with mitochondrial DNA depletion, encephalomyopathic form, with methylmalonic aciduria

Mitochondrial DNA depletion, encephalomyopathic form, with methylmalonic aciduria is associated with mutations in SUCLA2, the gene encoding a β subunit of succinate-CoA ligase, where 17 patients have been reported. Mutations in SUCLG1, encoding the α subunit of the enzyme, have been reported in only one family, where a homozygous 2xa0bp deletion was associated with fatal infantile lactic acidosis. We here report a patient with a novel homozygous missense mutation in SUCLG1, whose phenotype is similar to that of patients with SUCLA2 mutations.

Genetic testing in familial AD and FTD: Mutation and phenotype spectrum in a Danish cohort

Autosomal dominantly transmitted Alzheimers disease (AD) and frontotemporal dementia (FTD) are genetically heterogeneous disorders. To date, three genes have been identified in which mutations cause early‐onset autosomal dominant inherited AD: APP, PSEN1, and PSEN2. Mutations in two genes on chromosome 17, the MAPT and the PGRN genes, are associated with autosomal dominant inherited FTD. The aim of this study was to characterize the mutation spectrum and describe genotype‐phenotype correlations in families with inherited dementia. The identification of novel mutations and/or atypical genotype‐phenotype correlations contributes to further characterizing the disorders. DNA‐samples from the 90 index cases from a Danish referral‐based cohort representing families with presumed autosomal dominant inherited AD or FTD were screened for mutations in the known genes with sequencing, denaturing high‐performance liquid chromatography (DHPLC) and multiplex ligation‐dependent probe amplification (MLPA) techniques. Seven presumed pathogenic mutations (two PSEN1, one PSEN2, one APP, one MAPT, and two PGRN) were identified, including a novel PSEN2 mutation (V393M). No dosage aberrations were identified.

A novel presenilin 2 mutation (V393M) in early‐onset dementia with profound language impairment

Background:u2002 Mutations in the Presenilin 2 gene (PSEN2) are rare causes of Alzheimer’s disease (AD). Pathogenic mutations in the genes associated with autosomal dominant inherited AD have been shown to alter processing of the amyloid precursor protein (APP) resulting in a relative increase of the amount of Aβ42 peptide.

Phenotypic and genetic spectrum of Danish patients with ABCA4-related retinopathy

Background: Pathogenic variations in the ABCA4 gene were originally recognized as genetic background for the autosomal recessive disorders Stargardt disease and fundus flavimaculatus, but have expanded to embrace a diversity of retinal diseases, giving rise to the new diagnostic term, ABCA4-related retinopathy. Diagnostic genotyping of ABCA4 is complicated by the large size of the gene and the existence of approximately 600 known pathogenic variations, along with numerous rare polymorphisms. A commercial diagnostic array-based assay has been developed targeting known mutations, however a conclusive genetic diagnosis must rely on a comprehensive genetic screening as the mutation spectrum of ABCA4-related retinopathies continues to expand. Material and methods: Among 161 patients with a Stargardt-related phenotype previously assessed with the commercial ABCA4 mutation microarray, we analyzed the ABCA4 gene with High-resolution melting (HRM) in patients in whom the array analysis identified either a heterozygous mutation (nu2009=u200950) or no mutation (nu2009=u200930). Results: The HRM method detected each of the already known mutations and polymorphisms. We identified the second ABCA4 mutation in 31 of 50 heterozygous patients (62%). Several novel mutations were identified of which four were identified multiple times. The recurrent novel mutations were subsequently assessed among the 30 patients with possible ABCA4-related diseases, previously found to be negative for known ABCA4 mutations by array analysis. In total, 30 different mutations were identified of which 21 have not been described before. Conclusion: Scandinavian patients with ABCA4-related retinopathy appear to have a distinct mutation spectrum, which can be identified in patients of diverse clinical phenotypes.

Atypical early-onset Alzheimer's disease caused by the Iranian APP mutation.

BACKGROUNDnApproximately 1% of all cases of Alzheimers disease are inherited autosomal dominantly, and to date, three causative genes have been found, the Presenilin 1 (PSEN1) gene, the Presenilin 2 (PSEN2) gene and the Amyloid precursor protein (APP) gene. We describe atypical phenotypic features in a family with a pathogenic APP gene mutation and discuss possible explanations for these atypical features.nnnMETHODS AND RESULTSnWe report a family with a history of dementia compatible with autosomal dominant transmission. The disease course in the proband was not typical for Alzheimers disease as the diagnosis was preceded by 8 years of an isolated amnesia. Further, the proband had epilepsy with complex partial seizures and central degenerative autonomic failure as determined by clinical physiology. Sequencing the three known causative Alzheimer genes revealed a pathogenic missense mutation, APP Thr714Ala (the Iranian mutation).nnnCONCLUSIONSnThe atypical clinical phenotype with long prodromal phase, autonomic failure and seizures in this new proband with the APP Thr714Ala mutation illustrates the clinical heterogeneity in families with identical pathogenic mutations.

Detection and exclusion of carriers of ornithine transcarbamylase deficiency by RFLP analysis

By examining a restriction fragment length polymorphism (RFLP) detected by a gene specific DNA probe of ornithine transcarbamylase (OTC), we have been able to follow the segregation of the defective gene in a family with OTC deficiency. We have identified three sisters of the proband as carriers, and excluded a fourth as a carrier.

P1-314: A novel PSEN2 mutation in early-onset dementia with profound semantic loss

The common apolipoprotein E (APOE) e4 allele is strongly associated with risk of dementia and age at onset, but studies are inconclusive as to whether the e4 allele affects rate of progression or survival in demented patients. Furthermore, previous observations suggest a contribution of two APOE promoter polymorphisms (-491 A/T and -219 G/T) in dementia, but the influence of these two polymorphisms on survival in demented patients have not been evaluated yet.