Frequency of Cardiovascular Genetic Risk Factors in a Calabrian Population and Their Effects on Dementia.

BACKGROUND: Several genetic variants playing a key role in cholesterol levels, blood pressure, and vascular dysfunction influence the risk of Alzheimer's disease (AD) and vascular dementia (VaD). The many meta-analysis studies carried out on large numbers of samples in different populations have not provided clear results to date, because a trans-ethnic shift of risk genotypes in different populations is often observed. OBJECTIVES: To determine genotypes allele frequencies of the polymorphisms most frequently identified to be correlated with cardio-cerebrovascular disease and AD in a Southern Italy population and to investigate their possible association with dementia. METHODS: The genotype and allele frequencies of 13 cardio-cerebrovascular risk polymorphisms were assessed and their possible association with dementia was investigated in a case-control study, including 221 consecutive unrelated subjects diagnosed with dementia (120 subjects affected by AD, 55 by frontotemporal dementia, and 33 by vascular dementia) and 218 matched controls of Calabrian origin. RESULTS: Carriers of at least one APOEɛ4 allele resulted to be at higher risk of AD [OR(95% CI) = 2.721(1.477-5.011)] and VaD [OR(95% CI) = 6.205(2.356-16.342)] compared to non-carriers. Individuals with the IV genotype of the CETP polymorphism were more likely to have AD [OR(95% CI) = 2.427(1.364-4.319)] and VaD [OR(95% CI) = 3.649(1.455-9.152)] compared to subjects with the II-VV genotypes. CONCLUSION: CETP I405V polymorphism is likely a risk factor for AD and VaD in our cohort, independent of APOEɛ4 status. Unmodifiable genetic risk factors should be taken into account to promote a healthy lifestyle to prevent dementia.

The novel PSEN1 M84V mutation associated to frontal dysexecutive syndrome, spastic paraparesis, and cerebellar atrophy in a dominant Alzheimer's disease family.

We identified the novel PSEN1 pathogenic mutation M84V in 3 patients belonging to a large kindred affected by autosomal dominant Alzheimer's disease (AD). The clinical phenotype was characterized by early onset dementia in 14 affected subjects over 3 generations. Detailed clinical, imaging and genetic assessment was performed. We highlighted the presence of unusual symptoms such as frontal executive syndrome, psychosis and spastic paraparesis in these patients. Spastic paraparesis has been reported in other PSEN1 mutations in adjacent codons, suggesting that the position of the genetic defect may affect the clinical expression, although this phenotype can occur in mutations throughout the whole PSEN1 gene. Brain magnetic resonance imaging showed diffuse cortical atrophy, but also atrophy of cerebellar lobules, mainly involving Crus I, in 2 patients without cerebellar motor deficits. These neuroimaging results were consistent with recent findings about the association between sporadic AD and distinct and circumscribed cerebellar atrophy. The present work acknowledged the novel PSEN1 pathogenic mutation M84V and might contribute to the ongoing debate about the involvement of cerebellum in AD.

Role of Niemann-Pick Type C Disease Mutations in Dementia.

BACKGROUND: Several neurological and systemic diseases can cause dementia, beyond Alzheimer's disease. Rare genetic causes are often responsible for dementia with atypical features. Recently, mutations causative for Niemann-Pick type C disease (NPC) have also been implicated in neurodegenerative diseases. NPC is an autosomal recessive lipid storage disorder caused by mutations in NPC1 and NPC2 genes. In adults, clinical presentation mimicking other neurodegenerative diseases makes diagnosis difficult. Recent evidence suggests that heterozygous mutations in NPC genes may take on etiological significance. OBJECTIVE: To investigate the presence of NPC1 and NPC2 mutations in adults affected by neurodegenerative dementia plus. METHODS: We performed a genetic screening on 50 patients using a wide clinical and biochemical approach to characterize the phenotype of mutated patients. RESULTS: Sequencing analysis revealed four different and known heterozygous mutations in NPC1 and NPC2 genes. Patient 1 carried the p. F284LfsX26 in NPC1 and was affected by progressive supranuclear palsy-like syndrome. The remaining three patients showed a corticobasal syndrome and harbored the c.441+1G>A variant of NPC2 (patient 2), the missense p.N222 S mutation associated with the c.1947+8G>C variant in the splice region of intron 12 in NPC1 (patient 3), and the p.V30M mutation in NPC2 (patient 4), respectively. Filipin staining was abnormal in patients 1 and 2. mRNA analysis revealed an altered splicing of the NPC2 gene in patient 2. CONCLUSIONS: Heterozygous mutations of NPC1 and NPC2 genes could contribute to dementia plus, at least in a subset of patients. We highlight the occurrence of NPC1 and NPC2 heterozygous variants in dementia-plus as pathological event.

Homozygous carriers of APP A713T mutation in an autosomal dominant Alzheimer disease family.

OBJECTIVE: To report, for the first time, a large autosomal dominant Alzheimer disease (AD) family in which the APP A713T mutation is present in the homozygous and heterozygous state. To date, the mutation has been reported as dominant, and in the heterozygous state associated with familial AD and cerebrovascular lesions. METHODS: The family described here has been genealogically reconstructed over 6 generations dating back to the 19th century. Plasma ß-amyloid peptide was measured. Sequencing of causative AD genes was performed. RESULTS: Twenty-one individuals, all but 1 born from 2 consanguineous unions, were studied: 8 were described as affected through history, 5 were studied clinically and genetically, and 8 were asymptomatic at-risk subjects. The A713T mutation was detected in the homozygous state in 3 patients and in the heterozygous state in 8 subjects (6 asymptomatic and 2 affected). CONCLUSIONS: Our findings, also supported by the ß-amyloid plasma assay, confirm (1) the pathogenic role of the APP A713T mutation, (2) the specific phenotype (AD with cerebrovascular lesions) associated with this mutation, and (3) the large span of age at onset, not influenced by APOE, TOMM40, and TREM2 genes. No substantial differences concerning clinical phenotype were evidenced between heterozygous and homozygous patients, in line with the classic definition of dominance. Therefore, in this study, AD followed the classic definition of a dominant disease, contrary to that reported in a previously described AD family with recessive APP mutation. This confirms that genetic AD may be considered a disease with dominant and recessive traits of inheritance.

Novel N-terminal domain mutation in prion protein detected in 2 patients diagnosed with frontotemporal lobar degeneration syndrome.

Prion protein gene mutations have been associated with clinical pictures mimicking neurodegenerative diseases different from inherited prion diseases (IPD). We report a novel missense P39L mutation in the N-terminal domain of prion protein in 2 patients affected by frontotemporal lobar degeneration syndrome, negative for mutations in genes causative of dementia. Neither the first carrier, a 67-year-old male in which the onset was a progressive non-fluent aphasia, nor the second carrier, a 78-year-old male affected by frontotemporal dementia and parkinsonism, showed any clinical or instrumental findings suggestive of IPD. Genetic screening of healthy controls and in silico analysis provide support for the potential pathogenicity of this variant. Patient phenotypes, unclassifiable as prion disease, may depend on the location of the mutation in the N-terminal domain, outside the amyloid core of pathologic prion protein, although further functional studies are required to determine whether and how this mutation exerts its pathogenic effect. However, genetic screening of prion protein gene becomes relevant in familial degenerative dementia, particularly in geographical areas with high IPD prevalence.

Identification of three novel LRRK2 mutations associated with Parkinson's disease in a Calabrian population.

BACKGROUND: LRRK2 mutations are common in familial and sporadic Parkinson's disease (PD) cases. OBJECTIVE: We present a screening of the most frequently mutated exons of LRRK2 in Calabrian population. METHODS: Eighty-eight PD patients diagnosed according to standard criteria, underwent screening for LRRK2 mutations in exons 19, 21, 24, 25, 27, 29, 31, 32, 33, 35, 38, 40, 41, and 48. RESULTS: Eight LRRK2 variations were identified in nine patients affected by PD, including three novel missense variations (p.Phe1227Leu, p.Gly1520Ala, p.Ile2020Ser) and five previously identified mutations (p.Ala1151Thr, IVS31+3A>G, p.Arg1514Gln, p.Gly2019Ser, p.Thr2356Ile). LRRK2 frequency mutations were approximately 10.2% in all PD patients, 12% in familial, 8% in sporadic cases. The p.Gly2019Ser mutation was found in 2.3% of the total cohort and in 3.2% of sporadic cases. The clinical features of LRRK2-associated with PD in our patients were similar to those of idiopathic PD although most LRRK2 mutated patients presented with bradykinesia instead of tremor; 33.3% developed dementia. CONCLUSIONS: We identified three novel LRRK2 mutations and reported a higher frequency in Calabria compared to previously reported data possibly due to the relative genetic isolation of the Calabrian population. These findings contribute to the understanding of the role of LRKK2 variations in PD and provide additional genetic insight into this disease.

Role of TOMM40 rs10524523 polymorphism in onset of alzheimer's disease caused by the PSEN1 M146L mutation.

We investigated the association between TOMM40 rs10524523, age of onset, and memory performance in patients with the PSEN1 M146L mutation in a large familial Alzheimer's disease Calabrian kindred, with a wide variability of onset not attributable to APOE. APOE33/TOMM40VL/VL patients showed a tendency for an earlier age at onset compared to those with APOE33/TOMM40VL/S and APOE33/TOMM40S/S. Moreover, TOMM40VL/VL patients had better memory performance, when compared to TOMM40S/S but not to TOMM40VL/S patients, so there is not a dose-dependent effect. Our results suggest that, in the presence of the PSEN1 mutation, the slight difference in age of onset together with memory performance could be influenced by TOMM40 genotypes.

A novel pathogenic PSEN1 mutation in a family with Alzheimer's disease: phenotypical and neuropathological features.

We report a novel presenilin1 (PSEN1) gene mutation (I143 V) in a four-generation family with Alzheimer's disease. Clinical, molecular, and neuropathological examinations were performed on index patient; thirteen affected subjects were also identified. The index patient presented at 55 with personality changes, apathy, reduction of verbal fluency, and temporal and spatial disorientation. At 68, she showed visual hallucinations; blurred language, and rigidity. She became bedridden and died at 75. A novel mutation at codon 143 was found in PSEN1 gene, changing isoleucine to valine. The brain showed severe atrophy of the frontal and temporal lobes. Parenchymal amyloid-ß (Aß) deposits were abundant, diffuse to grey structures and contained Aß42, but very few Aß40. Amyloid angiopathy was absent. Neurofibrillary changes were severe. Our study confirms that PSEN1 mutations can be associated with unusual phenotypes. The peculiarity of the age at onset (not very early), the long course, and the frontal involvement, together with the rather complete absence of Aß40 and of amyloid angiopathy, widen the spectrum of PSEN1-linked phenotypes.

Novel MAPT Val75Ala mutation and PSEN2 Arg62Hys in two siblings with frontotemporal dementia.

A clinical and molecular overlap between Alzheimer's disease (AD) and frontotemporal dementia (FTD) has been reported. Presenilins have been associated with FTD or with FTD-like phenotype, while mutations in the MAPT gene have been linked to a clinical phenotype of AD. We performed a clinical and genetic examination in two FTD siblings and their family tree has been reconstructed. We identified a novel Val75Ala MAPT mutation in one patient and in the other the Arg62His Presenilin2 mutation. The DNA variations identified, defined mutations by frequency, per se are not causative of the disease. These mutations, possibly in association with other unknown environmental and genetic factors, may contribute to neurodegeneration. In this family, the disease might result from a genetically interconnected spectrum of altered pathways that could link most neurodegenerative disorders. Moreover, the novel mutation identified merits further functional studies that would contribute to the unravelling of such a complex field.

AbetaPP A713T mutation in late onset Alzheimer's disease with cerebrovascular lesions.

Mutations in the amyloid-beta protein precursor (AbetaPP) gene can cause autosomal dominant early-onset Alzheimer's disease, or Alzheimer's disease (AD) associated with cerebral amyloid angiopathy (CAA), cerebral hemorrhage, or both. We have previously reported that the AbetaPP A713T mutation is associated with AD and subcortical ischemic lesions at magnetic resonance imaging in a large family which neuropathology confirmed CAA, stroke, and AD lesions. The objective of this clinical and molecular study was to investigate AbetaPP gene mutations in 59 patients affected by AD with cerebrovascular lesions (CVLs) and a family history of dementia. We identified three affected subjects with the AbetaPP A713T mutation. Since the prevalence of this mutation worldwide is very low, a common founder could exist in southern Italy. The pathogenicity of this mutation was confirmed and the clinical AD phenotype with CVLs seems to be a distinctive feature in the southern Italian population. The identification of these patients suggests that genetic epidemiology in large cohorts of familial late onset AD with CVLs would increase the probability of identifying AbetaPP mutations.