Alexander disease with a novel GFAP insertion-deletion mutation mimicking progressive supranuclear palsy.

This report presents a case of Alexander disease showing clinical characteristics mimicking progressive supranuclear palsy (PSP). A 67-year-old woman complaining of motor disturbance exhibited severe atrophy of medulla, spinal cord, and midbrain tegmentum, as well as periventricular hyperintensity on cerebral MRI. Genetic analysis identified a novel in-frame deletion/insertion mutation in the exon 3 of the GFAP gene. Interestingly, neurological findings and decreased striatal uptake in dopamine transporter SPECT were suggestive of PSP. A novel GFAP gene mutation found in the present case may cause the unique clinical phenotype, which should be differentiated from PSP.

Type I Alexander disease: Update and validation of the clinical evolution-based classification.

BACKGROUND AND OBJECTIVES: Alexander disease (AxD) is a rare progressive leukodystrophy caused by autosomal dominant mutations in the Glial Fibrillary Acidic Protein (GFAP) gene. Three main disease classifications are currently in use, the traditional one defined by the age of onset, and two other based on clinical features at onset and brain MRI findings. Recently, we proposed a new classification, which is based on taking into consideration not only the presenting features, but also data related to the clinical course. In this study, we tried to apply this modified classification system to the cases of pediatric-onset AxD described in literature. METHODS: A literature review was conducted in PubMed for articles published between 1949 to date. Articles that reported no patient's medical history and the articles about Adult-onset AxD were excluded. We included patients with a confirmed diagnosis of pediatric-onset AxD and of whom information about age and symptoms at onset, developmental milestones and loss of motor and language skills was available. RESULTS: Clinical data from 205 patients affected with pediatric-onset AxD were retrospectively reviewed. Among these, we identified 65 patients, of whom we had enough information about the clinical course and developmental milestones, and we assessed their disease evolutionary trajectories over time. DISCUSSION: Our results confirm that patients with Type I AxD might be classified into four subgroups (Ia, Ib, Ic, Id) basing on follow up data. In fact, despite the great variability of phenotypes in AxD, there are some shared trajectories of the disease evolution over time.

Identification of a novel de novo pathogenic variant in GFAP in an Iranian family with Alexander disease by whole-exome sequencing.

BACKGROUND: Alexander disease (AxD) is a rare leukodystrophy with an autosomal dominant inheritance mode. Variants in GFAP lead to this disorder and it is classified into three distinguishable subgroups: infantile, juvenile, and adult-onset types. OBJECTIVE: The aim of this study is to report a novel variant causing AxD and collect all the associated variants with juvenile and adult-onset as well. METHODS: We report a 2-year-old female with infantile AxD. All relevant clinical and genetic data were evaluated. Search strategy for all AxD types was performed on PubMed. The extracted data include total recruited patients, number of patients carrying a GFAP variant, nucleotide and protein change, zygosity and all the clinical symptoms. RESULTS: A novel de novo variant c.217A > G: p. Met73Val was found in our case by whole-exome sequencing. In silico analysis categorized this variant as pathogenic. Totally 377 patients clinically diagnosed with juvenile or adult-onset forms were recruited in these articles, among them 212 patients were affected with juvenile or adult-onset form carrier of an alteration in GFAP. A total of 98 variants were collected. Among these variants c.262C > T 11/212 (5.18%), c.1246C > T 9/212 (4.24%), c.827G > T 8/212 (3.77%), c.232G > A 6/212 (2.83%) account for the majority of reported variants. CONCLUSION: This study highlighted the role of genetic in AxD diagnosing. It also helps to provide more information in order to expand the genetic spectrum of Iranian patients with AxD. Our literature review is beneficial in defining a better genotype-phenotype correlation of AxD disorder.

A novel in-frame GFAP p.E138_L148del mutation in Type II Alexander disease with atypical phenotypes.

Alexander disease (AxD) is a neurodegenerative astrogliopathy caused by mutation in the glial fibrillary acidic protein (GFAP) gene. A 42-year-old Korean man presented with temporary gait disturbance and psychiatric regression after a minor head trauma in the absence of bulbar symptoms and signs. Magnetic resonance images of the brain and spinal cord showed significant atrophy of the medulla oblongata and the entire spinal cord as well as contrast-enhanced T2 hypointensity in the basal ganglia. DNA sequencing revealed a novel 33-bp in-frame deletion mutation (p.Glu138_Leu148del) within the 1B rod domain of GFAP, which was predicted to be deleterious by PROVEAN analysis. To test whether the deletion mutant is disease-causing, we performed in vitro GFAP assembly and sedimentation assays, and GFAP aggregation assays in human adrenal carcinoma SW13 (Vim-) cells and rat primary astrocytes. All the assays revealed that GFAP p.Glu138_Leu148del is aggregation prone. Based on these findings, we diagnosed the patient with Type II AxD. This is a report that demonstrates the pathogenicity of InDel mutation of GFAP through functional studies. This patient's atypical presentation as well as the discrepancy between clinical symptoms and radiologic findings may extend the scope of AxD.

Type II Alexander disease with fragile X mental retardation 1 gene mutation.

Alexander disease (AxD) is a rare, autosomal dominant genetic disorder with an incidence of approximately 1 in 27,00.000. It is caused by a missense mutation in the GFAP gene encoding the glial fibrillary acidic protein. Fragile X-associated tremor/ataxia syndrome (FXTAS) is an X-linked dominant genetic disease, usually caused by a pre-mutation: an unmethylated expansion in the range of 50-200 CGG repeats in the fragile X mental retardation 1 (FMR1) gene. The clinical manifestations of these two diseases are complex and have some similarities. Both type II AxD and FXTAS may have ataxia as the first symptom. Here, we describe a case of type II AxD with ataxia as the first symptom accompanying a hemizygous mutation in the FMR1 gene (NM_001185081, exon13, c 0.1256C>T, p.T419M, g 0.147026507C>T). A sporadic genetic mutation led us to misdiagnose the patient with FXTAS initially. Whole-genome sequencing confirmed a heterozygous mutation in the GFAP gene (NM_002055.5, exon4, c 0.1158C>A, p.N386K, g 0.6310C>A). This report indicates that when the patient's clinical manifestation is ataxia, and imaging results suggest that the midbrain, medulla oblongata, and other subcerebellar structures are atrophied, AxD should be considered. Whole-genome sequencing is thus feasible to avoid missed diagnoses and misdiagnoses.

Does genetic anticipation occur in familial Alexander disease?

Alexander Disease (AxD) is a rare leukodystrophy caused by missense mutations of glial fibrillary acidic protein (GFAP). Primarily seen in infants and juveniles, it can present in adulthood. We report a family with inherited AxD in which the mother presented with symptoms many years after her daughter. We reviewed the age of onset in all published cases of familial AxD and found that 32 of 34 instances of parent-offspring pairs demonstrated an earlier age of onset in offspring compared to the parent. We suggest that genetic anticipation occurs in familial AxD and speculate that genetic mosaicism could explain this phenomenon.

[A case of Alexander disease presented with dystonia of lower limb and decreased dopaminergic uptake in dopamine transporter scintigraphy].

A 50-year-old woman developed gait disturbances and dysarthria since the past 2 years. She also presented with dystonia and hypokinesia of her left lower limb, and orthostatic hypotension. The dopamine transporter SPECT with 123I ioflupane showed abnormal scans in bilateral striatum. Cerebral MRI revealed atrophy and signal changes in the medulla and spinal cord, from which Alexander disease (AxD) was suspected. Consequently, we checked the Glial fibrillary acidic protein (GFAP) gene. The analysis of the gene detected a heterozygous c.219G>T mutation, which was the first mutation reported in Japan, and finally she was diagnosed with AxD. Dystonia is relatively rare in AxD patients, but this case demonstrated that AxD should be listed in the differential diagnosis of extrapyramidal syndromes with abnormalities of the medulla and spinal cord on MRI.

Clinical characteristics of Alexander disease.

Alexander disease (ALXDRD) is a primary astrocyte disease caused by GFAP gene mutation. The clinical features of ALXDRD vary from infantile-onset cerebral white matter involvement to adult-onset brainstem involvement. Several studies revealed that the level of GFAP overexpression is correlated with disease severity, and basic research on therapies to reduce abnormal GFAP accumulation has recently been published. Therefore, the accumulation of clinical data to advance understanding of the natural history is essential for clinical trials expected in the future. This review focuses on the clinical characteristics of ALXDRD including the clinical symptoms, imaging findings and genetics to provide diagnostic information useful in daily clinical practice.

[Clinical characteristics and diagnostic criteria on Alexander disease].

Alexander disease (ALXDRD) is a primary astrocyte disease caused by glial fibrillary acidic protein (GFAP) gene mutation. ALXDRD had been clinically regarded as a cerebral white matter disease that affects only children for about 50 years since the initial report in 1949; however, in the early part of the 21st century, case reports of adult-onset ALXDRD with medulla and spinal cord lesions increased. Basic research on therapies to reduce abnormal GFAP accumulation, such as drug-repositioning and antisense oligonucleotide suppression, has recently been published. The accumulation of clinical data to advance understanding of natural history is essential for clinical trials expected in the future. In this review, I classified ALXDRD into two subtypes: early-onset and late-onset, and detail the clinical symptoms, imaging findings, and genetic characteristics as well as the epidemiology and historical changes in the clinical classification described in the literature. The diagnostic criteria based on Japanese ALXDRD patients that are useful in daily clinical practice are also mentioned.

Site-specific phosphorylation and caspase cleavage of GFAP are new markers of Alexander disease severity.

Alexander disease (AxD) is a fatal neurodegenerative disorder caused by mutations in glial fibrillary acidic protein (GFAP), which supports the structural integrity of astrocytes. Over 70 GFAP missense mutations cause AxD, but the mechanism linking different mutations to disease-relevant phenotypes remains unknown. We used AxD patient brain tissue and induced pluripotent stem cell (iPSC)-derived astrocytes to investigate the hypothesis that AxD-causing mutations perturb key post-translational modifications (PTMs) on GFAP. Our findings reveal selective phosphorylation of GFAP-Ser13 in patients who died young, independently of the mutation they carried. AxD iPSC-astrocytes accumulated pSer13-GFAP in cytoplasmic aggregates within deep nuclear invaginations, resembling the hallmark Rosenthal fibers observed in vivo. Ser13 phosphorylation facilitated GFAP aggregation and was associated with increased GFAP proteolysis by caspase-6. Furthermore, caspase-6 was selectively expressed in young AxD patients, and correlated with the presence of cleaved GFAP. We reveal a novel PTM signature linking different GFAP mutations in infantile AxD.

A novel mutation in the GFAP gene expands the phenotype of Alexander disease.

BACKGROUND: Alexander disease, an autosomal dominant leukodystrophy, is caused by missense mutations in GFAP. Although mostly diagnosed in children, associated with severe leukoencephalopathy, milder adult forms also exist. METHODS: A family affected by adult-onset spastic paraplegia underwent neurological examination and cerebral MRI. Two patients were sequenced by whole exome sequencing (WES). A candidate variant was functionally tested in an astrocytoma cell line. RESULTS: The novel variant in GFAP (Glial Fibrillary Acidic Protein) N-terminal head domain (p.Gly18Val) cosegregated in multiple relatives (LOD score: 2.7). All patients, even those with the mildest forms, showed characteristic signal changes or atrophy in the brainstem and spinal cord MRIs, and abnormal MRS. In vitro, this variant did not cause significant protein aggregation, in contrast to most Alexander disease mutations characterised so far. However, cell area analysis showed larger size, a feature previously described in patients and mouse models. CONCLUSION: We suggest that this variant causes variable expressivity and an attenuated phenotype of Alexander disease type II, probably associated with alternative pathogenic mechanisms, that is, astrocyte enlargement. GFAP analysis should be considered in adult-onset neurological presentations with pyramidal and bulbar symptoms, in particular when characteristic findings, such as the tadpole sign, are present in MRI. WES is a powerful tool to diagnose atypical cases.

Adult-onset Alexander disease with a heterozygous D128N GFAP mutation: a pathological study.

The various forms of Alexander disease (AD) have been linked to heterozygous point mutations in the coding region of the human Glial Fibrillary Acidic Protein (GFAP) gene. The aim of this study was to confirm and characterise an adult variant of AD based on the presence of Rosenthal fibres, which were identified at brain autopsy. We performed histological and immunohistochemical studies and mutation screening by cycle sequencing of exons 1, 4, 6, and 8. A heterozygous D128N GFAP mutation, previously described in three other cases of adult-onset AD (AOAD), was genetically confirmed. The mutation was seemingly sporadic. Symptoms of the female, 65-year-old patient started with occasionally asymmetric motor impairment and concluded, 23 months later, with a lack of spontaneous movement in all four limbs, reduced consciousness, an acute respiratory problem, and eventually lethal exitus. The most striking characteristics were a cerebellar syndrome with subsequent clinical signs due to brainstem and spinal cord involvement. The final diagnosis was based on a complete autopsy, detection of Rosenthal fibres, GFAP, vimentin, alpha B-crystallin, ubiquitin, hsp27, neurofilament, and synaptophysin, and the identification of the corresponding GFAP gene mutation. Blood analyses were positive for ANA and rheumatoid factor. In conclusion, this work describes sporadic, rapidly advancing AOAD in a female patient and links it with other published cases with the same mutation. Reflections are provided on the influence of vasculitis and ANA in AD as well as the presence of Rosenthal fibres in the neurohypophysis.

[A case of Alexander disease with dropped head syndrome].

A 51-year-old woman presented with progressive weakness of the neck extensor muscles and gait disturbances since the past 6 years. In addition, she presented with symptoms such as dysarthria, dysphagia, bladder, and rectal disturbances. Bilateral plantar reflex was positive. Her gait was short-stepped-spastic. Brain and cervical MRI showed atrophy of the medulla and spinal cord. As these imaging features were suggestive of Alexander disease (AxD), we sequenced the GFAP gene. We identified a heterozygous c.368T>C missense mutation of the GFAP gene in the patient. This was the first case of the mutation in Japanese patients, and subsequently, she was diagnosed with AxD type 2. There are a few studies which reported that patients with AxD complained of dropped head syndrome. Dropped head syndrome can be the initial manifestation of AxD.