Familial frontotemporal dementia with neuronal intranuclear inclusions is not a polyglutamine expansion disease

Neuronal intranuclear inclusion disease mimicking acute cerebellitis: A case report

BACKGROUND

Neuronal intranuclear inclusion disease (NIID) is an unusual autosomal dominant, chronic progressive neurodegenerative disease. The clinical manifestations of NIID are complex and varied, complicating its clinical diagnosis. To the best of our knowledge, this report is the first to document sporadic adult-onset NIID mimicking acute cerebellitis (AC) that was finally diagnosed by imaging studies, skin biopsy, and genetic testing.

CASE SUMMARY

A 63-year-old man presented with fever, gait unsteadiness, dysarthria, and an episode of convulsion. His serum levels of white blood cells and C-reactive protein were significantly elevated. T2-weighted brain magnetic resonance imaging and fluid attenuation inversion recovery sequences showed bilateral high-intensity signals in the medial part of the cerebellar hemisphere beside the vermis. While we initially considered a diagnosis of AC, the patient’s symptoms improved significantly without special treatment, prompting our consideration of NIID. Diffusion-weighted imaging showed hyperintensity in the corticomedullary junction. Skin biopsy revealed eosinophilic inclusions positive for anti-p62 in epithelial sweat-gland cells. GGC repeat expansions in the Notch 2 N-terminal like C gene confirmed the diagnosis of NIID.

CONCLUSION

For patients with clinical manifestations mimicking AC, the possibility of underlying NIID should be considered along with prompt rigorous examinations.

Cognitive impairment in lacunar strokes: the SPS3 trial

OBJECTIVE

Lacunar strokes are a leading cause of cognitive impairment and vascular dementia. However, adequate characterization of cognitive impairment is lacking. The aim of this study was to estimate the prevalence and characterize the neuropsychological impairment in lacunar stroke patients.

METHODS

All English-speaking participants in the Secondary Prevention of Small Subcortical Strokes (SPS3) trial (National Clinical Trial 00059306) underwent neuropsychological testing at baseline. Raw scores were converted to z scores using published norms. Those with impairment (z ≤ -1.5) in memory and/or nonmemory domains were classified as having mild cognitive impairment (MCI).

RESULTS

Among the 1,636 participants, average z scores on all tests were < 0, with the largest deficits seen on tests of episodic memory (range of means, -0.65 to -0.92), verbal fluency (mean, -0.89), and motor dexterity (mean, -2.5). Forty-seven percent were classified as having MCI (36% amnestic, 37% amnestic multidomain, 28% nonamnestic). Of those with modified Rankin score 0-1 and Barthel score = 100, 41% had MCI. Younger age (odds ratio [OR] per 10-year increase, 0.87), male sex (OR, 1.3), less education (OR, 0.13-0.66 for higher education levels compared to 0-4 years education), poststroke disability (OR, 1.4), and impaired activities of daily living (OR, 1.8) were independently associated with MCI.

INTERPRETATION

In this large, well-characterized cohort of lacunar stroke patients, MCI was present in nearly half, including many with minimal or no physical disabilities. Cognitive dysfunction in lacunar stroke patients may commonly be overlooked in clinical practice but may be as important as motor and sensory sequelae.

Maternal transmission of Alzheimer's disease: prodromal metabolic phenotype and the search for genes

After advanced age, having a parent affected with Alzheimer's disease (AD) is the most significant risk factor for developing AD among cognitively normal (NL) individuals. Although rare genetic mutations have been identified among the early-onset forms of familial AD (EOFAD), the genetics of the more common forms of late-onset AD (LOAD) remain elusive. While some LOAD cases appear to be sporadic in nature, genetically mediated risk is evident from the familial aggregation of many LOAD cases. The patterns of transmission and biological mechanisms through which a family history of LOAD confers risk to the offspring are not known. Brain imaging studies using 2-[ (18) F]fluoro-2-deoxy-D-glucose positron emission tomography ((18)F-FDG PET) have shown that NL individuals with a maternal history of LOAD, but not with a paternal family history, express a phenotype characterised by a pattern of progressive reductions of brain glucose metabolism, similar to that in AD patients. As maternally inherited AD may be associated with as many as 20 per cent of the total LOAD population, understanding the causes and mechanisms of expression of this form of AD is of great relevance. This paper reviews known genetic mutations implicated in EOFAD and their effects on brain chemistry, structure and function; epidemiology and clinical research findings in LOAD, including in vivo imaging findings showing selective patterns of hypometabolism in maternally inherited AD; possible genetic mechanisms involved in maternal transmission of AD, including chromosome X mutations, mitochondrial DNA and imprinting; and genetic mechanisms involved in other neurological disorders with known or suspected maternal inheritance. The review concludes with a discussion of the potential role of brain imaging for identifying endophenotypes in NL individuals at risk for AD, and for directing investigation of potential susceptibility genes for AD.

Neuroanatomic profile of polyglutamine immunoreactivity in Huntington disease brains

A pathologic hallmark of Huntington disease (HD) is the presence of intraneuronal aggregates of polyglutamine-containing huntingtin protein fragments. Monoclonal antibody 1C2 is a commercial antibody to normal human TATA-binding protein that detects long stretches of glutamine residues. Using 1C2 as a surrogate marker formutant huntingtin protein, we immunostained 19 HD cases, 10 normal controls, and 10 cases of frontotemporal degeneration with ubiquitinated inclusions as diseased controls. In the HD cases, there was consistent 1C2 immunoreactivity in the neocortex, striatum, hippocampus, lateral geniculate body, basis pontis, medullary reticular formation, and cerebellar dentate nucleus. The normal and diseased controls demonstrated 1C2 immunoreactivity only in the substantia nigra, locus coeruleus, and pituitary gland. Staining of 5 HD cases and 5 normal controls revealed a less consistent and less diagnostically useful morphologic immunoreactivity profile. These results indicate that widespread 1C2 immunoreactivity is present in diverse central nervous system areas in HD, and that in the appropriate setting, 1C2 staining can be a useful tool in the postmortem diagnosis of HD when neuromelanin-containing neuronal populations are avoided.

Molecular characterization of novel progranulin (GRN) mutations in frontotemporal dementia

Frontotemporal dementia (FTD) is a clinical term encompassing dementia characterized by the presence of two major phenotypes: 1) behavioral and personality disorder, and 2) language disorder, which includes primary progressive aphasia and semantic dementia. Recently, the gene for familial frontotemporal lobar degeneration (FTLD) with ubiquitin-positive, tau-negative inclusions (FTLD-U) linked to chromosome 17 was cloned. In the present study, 62 unrelated patients from the Washington University Alzheimer's Disease Research Center and the Midwest Consortium for FTD with clinically diagnosed FTD and/or neuropathologically characterized cases of FTLD-U with or without motor neuron disease (MND) were screened for mutations in the progranulin gene (GRN; also PGRN). We discovered two pathogenic mutations in four families: 1) a single-base substitution within the 3' splice acceptor site of intron 6/exon 7 (g.5913A>G [IVS6-2A>G]) causing skipping of exon 7 and premature termination of the coding sequence (PTC); and 2) a missense mutation in exon 1 (g.4068C>A) introducing a charged amino acid in the hydrophobic core of the signal peptide at residue 9 (p.A9D). Functional analysis in mutation carriers for the splice acceptor site mutation revealed a 50% decrease in GRN mRNA and protein levels, supporting haploinsufficiency. In contrast, there was no significant difference in the total GRN mRNA between cases and controls carrying the p.A9D mutation. Further, subcellular fractionation and confocal microscopy indicate that although the mutant protein is expressed, it is not secreted, and appears to be trapped within an intracellular compartment, possibly resulting in a functional haploinsufficiency.