Giuseppe Borghero

A hexanucleotide repeat expansion in C9ORF72 is the cause of chromosome 9p21-linked ALS-FTD

The chromosome 9p21 amyotrophic lateral sclerosis-frontotemporal dementia (ALS-FTD) locus contains one of the last major unidentified autosomal-dominant genes underlying these common neurodegenerative diseases. We have previously shown that a founder haplotype, covering the MOBKL2b, IFNK, and C9ORF72 genes, is present in the majority of cases linked to this region. Here we show that there is a large hexanucleotide (GGGGCC) repeat expansion in the first intron of C9ORF72 on the affected haplotype. This repeat expansion segregates perfectly with disease in the Finnish population, underlying 46.0% of familial ALS and 21.1% of sporadic ALS in that population. Taken together with the D90A SOD1 mutation, 87% of familial ALS in Finland is now explained by a simple monogenic cause. The repeat expansion is also present in one-third of familial ALS cases of outbred European descent, making it the most common genetic cause of these fatal neurodegenerative diseases identified to date.

Frequency of the C9orf72 hexanucleotide repeat expansion in patients with amyotrophic lateral sclerosis and frontotemporal dementia: A cross-sectional study

Summary Background We aimed to accurately estimate the frequency of a hexanucleotide repeat expansion in C9orf72 that has been associated with a large proportion of cases of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Methods We screened 4448 patients diagnosed with ALS (El Escorial criteria) and 1425 patients with FTD (Lund-Manchester criteria) from 17 regions worldwide for the GGGGCC hexanucleotide expansion using a repeat-primed PCR assay. We assessed familial disease status on the basis of self-reported family history of similar neurodegenerative diseases at the time of sample collection. We compared haplotype data for 262 patients carrying the expansion with the known Finnish founder risk haplotype across the chromosomal locus. We calculated age-related penetrance using the Kaplan-Meier method with data for 603 individuals with the expansion. Findings In patients with sporadic ALS, we identified the repeat expansion in 236 (7·0%) of 3377 white individuals from the USA, Europe, and Australia, two (4·1%) of 49 black individuals from the USA, and six (8·3%) of 72 Hispanic individuals from the USA. The mutation was present in 217 (39·3%) of 552 white individuals with familial ALS from Europe and the USA. 59 (6·0%) of 981 white Europeans with sporadic FTD had the mutation, as did 99 (24·8%) of 400 white Europeans with familial FTD. Data for other ethnic groups were sparse, but we identified one Asian patient with familial ALS (from 20 assessed) and two with familial FTD (from three assessed) who carried the mutation. The mutation was not carried by the three Native Americans or 360 patients from Asia or the Pacific Islands with sporadic ALS who were tested, or by 41 Asian patients with sporadic FTD. All patients with the repeat expansion had (partly or fully) the founder haplotype, suggesting a one-off expansion occurring about 1500 years ago. The pathogenic expansion was non-penetrant in individuals younger than 35 years, 50% penetrant by 58 years, and almost fully penetrant by 80 years. Interpretation A common Mendelian genetic lesion in C9orf72 is implicated in many cases of sporadic and familial ALS and FTD. Testing for this pathogenic expansion should be considered in the management and genetic counselling of patients with these fatal neurodegenerative diseases. Funding Full funding sources listed at end of paper (see Acknowledgments).

Clinical characteristics of patients with familial amyotrophic lateral sclerosis carrying the pathogenic GGGGCC hexanucleotide repeat expansion of C9ORF72

A large hexanucleotide (GGGGCC) repeat expansion in the first intron of C9ORF72, a gene located on chromosome 9p21, has been recently reported to be responsible for ~40% of familial amyotrophic lateral sclerosis cases of European ancestry. The aim of the current article was to describe the phenotype of amyotrophic lateral sclerosis cases carrying the expansion by providing a detailed clinical description of affected cases from representative multi-generational kindreds, and by analysing the age of onset, gender ratio and survival in a large cohort of patients with familial amyotrophic lateral sclerosis. We collected DNA and analysed phenotype data for 141 index Italian familial amyotrophic lateral sclerosis cases (21 of Sardinian ancestry) and 41 German index familial amyotrophic lateral sclerosis cases. Pathogenic repeat expansions were detected in 45 (37.5%) patients from mainland Italy, 12 (57.1%) patients of Sardinian ancestry and nine (22.0%) of the 41 German index familial amyotrophic lateral sclerosis cases. The disease was maternally transmitted in 27 (49.1%) pedigrees and paternally transmitted in 28 (50.9%) pedigrees (P = non-significant). On average, children developed disease 7.0 years earlier than their parents [children: 55.8 years (standard deviation 7.9), parents: 62.8 (standard deviation 10.9); P = 0.003]. Parental phenotype influenced the type of clinical symptoms manifested by the child: of the 13 cases where the affected parent had an amyotrophic lateral sclerosis-frontotemporal dementia or frontotemporal dementia, the affected child also developed amyotrophic lateral sclerosis-frontotemporal dementia in nine cases. When compared with patients carrying mutations of other amyotrophic lateral sclerosis-related genes, those with C9ORF72 expansion had commonly a bulbar onset (42.2% compared with 25.0% among non-C9ORF72 expansion cases, P = 0.03) and cognitive impairment (46.7% compared with 9.1% among non-C9ORF72 expansion cases, P = 0.0001). Median survival from symptom onset among cases carrying C9ORF72 repeat expansion was 3.2 years lower than that of patients carrying TARDBP mutations (5.0 years; 95% confidence interval: 3.6-7.2) and longer than those with FUS mutations (1.9 years; 95% confidence interval: 1.7-2.1). We conclude that C9ORF72 hexanucleotide repeat expansions were the most frequent mutation in our large cohort of patients with familial amyotrophic lateral sclerosis of Italian, Sardinian and German ancestry. Together with mutation of SOD1, TARDBP and FUS, mutations of C9ORF72 account for ~60% of familial amyotrophic lateral sclerosis in Italy. Patients with C9ORF72 hexanucleotide repeat expansions present some phenotypic differences compared with patients with mutations of other genes or with unknown mutations, namely a high incidence of bulbar-onset disease and comorbidity with frontotemporal dementia. Their pedigrees typically display a high frequency of cases with pure frontotemporal dementia, widening the concept of familial amyotrophic lateral sclerosis.

Large proportion of amyotrophic lateral sclerosis cases in sardinia due to a single founder mutation of the TARDBP gene

OBJECTIVE To perform an extensive screening for mutations of amyotrophic lateral sclerosis (ALS)-related genes in a consecutive cohort of Sardinian patients, a genetic isolate phylogenically distinct from other European populations. DESIGN Population-based, prospective cohort study. PATIENTS A total of 135 Sardinian patients with ALS and 156 healthy control subjects of Sardinian origin who were age- and sex-matched to patients. INTERVENTION Patients underwent mutational analysis for SOD1, FUS, and TARDBP. RESULTS Mutational screening of the entire cohort found that 39 patients (28.7%) carried the c.1144G>A (p.A382T) missense mutation of the TARDBP gene. Of these, 15 had familial ALS (belonging to 10 distinct pedigrees) and 24 had apparently sporadic ALS. None of the 156 age-, sex-, and ethnicity-matched controls carried the pathogenic variant. Genotype data obtained for 5 ALS cases carrying the p.A382T mutation found that they shared a 94-single-nucleotide polymorphism risk haplotype that spanned 663 Kb across the TARDBP locus on chromosome 1p36.22. Three patients with ALS who carry the p.A382T mutation developed extrapyramidal symptoms several years after their initial presentation with motor weakness. CONCLUSIONS The TARDBP p.A382T missense mutation accounts for approximately one-third of all ALS cases in this island population. These patients share a large risk haplotype across the TARDBP locus, indicating that they have a common ancestor.

C9ORF72 hexanucleotide repeat expansions in the Italian sporadic ALS population.

It has been recently reported that a large proportion of patients with familial amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are associated with a hexanucleotide (GGGGCC) repeat expansion in the first intron of C9ORF72. We have assessed 1757 Italian sporadic ALS cases, 133 from Sardinia, 101 from Sicily, and 1523 from mainland Italy. Sixty (3.7%) of 1624 mainland Italians and Sicilians and 9 (6.8%) of the 133 Sardinian sporadic ALS cases carried the pathogenic repeat expansion. None of the 619 regionally matched control samples (1238 chromosomes) carried the expansion. Twenty-five cases (36.2%) had behavioral FTD in addition to ALS. FTD or unspecified dementia was also detected in 19 pedigrees (27.5%) in first-degree relatives of ALS patients. Cases carrying the C9ORF72 hexanucleotide expansion survived 1 year less than cases who did not carry this mutation. In conclusion, we found that C9ORF72 hexanucleotide repeat expansions represents a sizeable proportion of apparent sporadic ALS in the Italian and Sardinian population, representing by far the most common mutation in Italy and the second most common in Sardinia.

Lithium carbonate in amyotrophic lateral sclerosis: lack of efficacy in a dose-finding trial

Background: A neuroprotective effect of lithium in amyotrophic lateral sclerosis (ALS) has been recently reported. We performed a multicenter trial with lithium carbonate to assess its tolerability, safety, and efficacy in patients with ALS, comparing 2 different target blood levels (0.4–0.8 mEq/L, therapeutic group [TG], vs 0.2–0.4 mEq/L, subtherapeutic group [STG]). Methods: The study was a multicenter, single-blind, randomized, dose-finding trial, conducted from May 2008 to November 2009 in 21 Italian ALS centers. The trial was registered with the public database of the Italian Agency for Drugs (http://oss-sper-clin.agenziafarmaco.it/) (EudraCT number 2008–001094-15). Results: As of October 2009, a total of 171 patients had been enrolled, 87 randomized to the TG and 84 to the STG. The interim data analysis, performed per protocol, showed that 117 patients (68.4%) discontinued the study because of death/tracheotomy/severe disability, adverse events (AEs)/serious AEs (SAEs), or lack of efficacy. The Data Monitoring Committee recommended stopping the trial on November 2, 2009. Conclusions: Lithium was not well-tolerated in this cohort of patients with ALS, even at subtherapeutic doses. The 2 doses were equivalent in terms of survival/severe disability and functional data. The relatively high frequency of AEs/SAEs and the reduced tolerability of lithium raised serious doubts about its safety in ALS. Classification of evidence: The study provides Class II evidence that therapeutic (0.4–0.8 mEq/L) vs subtherapeutic (0.2–0.4 mEq/L) lithium carbonate did not differ in the primary outcome of efficacy (survival/loss of autonomy) in ALS. Both target levels led to dropouts in more than 30% of participants due to patient-perceived lack of efficacy and AEs.

ALS/FTD phenotype in two Sardinian families carrying both C9ORF72 and TARDBP mutations

Background In the isolated population of Sardinia, a Mediterranean island, ∼25% of ALS cases carry either a p.A382T mutation of the TARDBP gene or a GGGGCC hexanucleotide repeat expansion in the first intron of the C9ORF72 gene. Objective To describe the co-presence of two genetic mutations in two Sardinian ALS patients. Methods We identified two index ALS cases carrying both the p.A382T missense mutation of TARDBP gene and the hexanucleotide repeat expansion of C9ORF72 gene. Results The index case of Family A had bulbar ALS and frontemporal dementia (FTD) at 43. His father, who carried the hexanucleotide repeat expansion of C9ORF72 gene, had spinal ALS and FTD at 64 and his mother, who carried the TARDBP gene p.A382T missense mutation, had spinal ALS and FTD at 69. The index case of Family B developed spinal ALS without FTD at 35 and had a rapid course to respiratory failure. His parents are healthy at 62 and 63. The two patients share the known founder risk haplotypes across both the C9ORF72 9p21 locus and the TARDBP 1p36.22 locus. Conclusions Our data show that in rare neurodegenerative causing genes can co-exist within the same individuals and are associated with a more severe disease course.

Amyotrophic Lateral Sclerosis–Frontotemporal Lobar Dementia in 3 Families With p.Ala382Thr TARDBP Mutations

BACKGROUND TAR DNA-binding protein 43, encoded by the TARDBP gene, has been identified as the major pathological protein of frontotemporal lobar dementia (FTLD) with or without amyotrophic lateral sclerosis (ALS) and sporadic ALS. Subsequently, mutations in the TARDBP gene have been detected in 2% to 3% of patients with ALS (both familial and sporadic ALS). However, to our knowledge, there is only 1 description of 2 patients with FTLD and TARDBP gene mutations who later developed motor neuron disease. OBJECTIVE To describe cognitive abnormalities in 3 Italian families with familial ALS and TARDBP gene mutations. DESIGN, SETTING, AND PARTICIPANTS Genetic, neuropsychological, and neuroimaging analyses in 36 patients with familial non-superoxide dismutase 1 gene (SOD1) ALS and 280 healthy controls. Main Outcome Measure We identified 3 index cases of familial ALS carrying the p.Ala382Thr missense mutation of the TARDBP gene and with clinical, neuroimaging, and neuropsychological features of FTLD. RESULTS The p.Ala382Thr missense mutation of the TARDBP gene was absent in the 280 controls. It was present in all affected members of the 3 families for whom DNA was available. All affected members of the 3 families developed FTLD after the onset of ALS, confirmed by neuropsychological testing and hypometabolism in frontal associative areas assessed with fludeoxyglucose F 18 positron emission tomography and computed tomography. CONCLUSIONS Three apparently unrelated families with familial ALS carrying the p.Ala382Thr TARDBP missense mutation developed FTLD. In these families, FTLD cosegregates with ALS. Patients with ALS carrying TARDBP mutations may develop FTLD.

Frontotemporal dementia with psychosis, parkinsonism, visuo-spatial dysfunction, upper motor neuron involvement associated to expansion of C9ORF72: a peculiar phenotype?

Dear Sirs, From 2006, a locus on chromosome 9p21 has been associated with a large proportion of ALS and FTD [1–3]. Recently, two independent groups have identified a hexanucleotide repeat expansion in noncoding region of the C9ORF72 gene as the cause of chromosome 9p21-linked ALS-FTD [4, 5]. We report the case of a 64-year-old man who presented with a 3-year history of delusional mystic thoughts, auditive, visual, and olfactory hallucinations, and hyperreligiosity. The patient later developed progressive apathy, dysphoric mood, hyperphagia, self-care reduction, and progressive cognitive decline with motor retardation. The mans father had died at age 68 after committing suicide, and his older brother developed parkinsonism associated with behavioral disturbances at age 60 and died 2 years later. Neuropsychological assessment of this patient, performed 3 years after the onset of neurological symptoms, demonstrated bradyphrenia, marked impairment of attention and executive functions, marked constructional apraxia, mild visual and verbal long-term memory deficit, mild anomia, emotional lability, fatuity, and mild utilization behavior. Blood exams, thyroid antibodies and hormones, vitamin B12, folic acid, and TPHA were all normal. Neurological examination revealed symmetric akinetic-rigid syndrome characterized by hypomimia, dysarthria, camptocormia with anterocollis, and diffuse bradykinesia. Brain MRI documented atrophy mainly frontotemporal but with consistent posterior region involvement (Fig. 1). Perfusion SPECT with 99Tc-ethylene cystine dimer (ECD) showed a marked reduction of the uptake in the frontotemporal and parietal regions bilaterally (Fig. 1). A few months after the first neurological assessment, the patient had a rapid progression to a severe dementia and developed marked pyramidal involvement of upper and lower limbs with an inability to walk. The patient became anarthric, dysphagic, and developed constipation. The nature of the dysarthria was both pseudobulbar and extrapyramidal. Lower motor neuron signs or symptoms were not present. Later the patient was admitted to a surgical department for intestinal sub-occlusion; during the hospitalization, a pulmonary embolism (PE) occurred. The patient died 4 years after the first neurological manifestations. Mutations of TARDBP, MAPT, and PGRN genes were excluded. The patient has been found positive for a GGGGCC hexanucleotide repeat expansion in the first intron of C9ORF72 gene (>50). Our patient developed a dementia with prominent behavioral disturbances at presentation, characterized mostly by psychosis with mystic themes. The neuropsychological evaluation demonstrated a marked cognitive impairment with predominant frontal syndrome. An important involvement of visuo-spatial functions was also found (Fig. 2). This cognitive impairment, associated with multimodal hallucinations and parkinsonism, which presented before the onset of upper motor neuron signs, raised a differential diagnosis between FTD and dementia with Lewy bodies (DLB). A few cases have been reported with similar diagnostic difficulties [6]. The parkinsonism was not drug-induced. The dementia profile of our patient was consistent with a behavioral variant of FTD. He presented a positive family history for similar disturbances. Some features of our case are atypical for FTD, like psychosis, constructional apraxia associated with the frontal syndrome, atrophy, and perfusional deficit extended to posterior cortical areas. Hallucinations are possible but not common in FTD [7], whereas they are a core clinical feature in the diagnostic criteria of DLB [8]. Of note, some clinical aspects of our case have been reported in patients with ALS-FTD linked to the locus 9p21, such as the presence of parkinsonism, psychosis, visuo-spatial impairment, and brain atrophy with parietal and occipital lobe involvement [9, 10]. We propose that delusions with multimodal hallucinations at presentation, visuo-spatial dysfunction, and frontotemporal brain atrophy also involving posterior areas could be aspects of a possible distinctive phenotype of FTD-parkinsonism-upper motor neuron disease linked to the C9ORF72 gene hexanucleotide expansions. Fig. 1 a–c Brain MRI T1-weighted transversal scans showing bilateral frontotemporal and posterior cerebral areas atrophy. d–f Perfusion single-photon emission computed tomography (SPECT) with 99Tc-ethylene cystine dimer (ECD). The transversal ... Fig. 2 Severe constructional apraxia demonstrated by the copy of a simple drawing

Genetic architecture of ALS in Sardinia

Conserved populations, such as Sardinians, displaying elevated rates of familial or sporadic amyotrophic lateral sclerosis (ALS) provide unique information on the genetics of the disease. Our aim was to describe the genetic profile of a consecutive series of ALS patients of Sardinian ancestry. All ALS patients of Sardinian ancestry, identified between 2008 and 2013 through the Italian ALS Genetic Consortium, were eligible to be included in the study. Patients and controls underwent the analysis of TARDBP, C9ORF72, SOD1, and FUS genes. Genetic mutations were identified in 155 out of 375 Sardinian ALS cases (41.3%), more commonly the p.A382T and p.G295S mutations of TARDBP and the GGGGCC hexanucleotide repeat expansion of C9ORF72. One patient had both p.G295S and p.A382T mutations of TARDBP and 8 carried both the heterozygous p.A382T mutation of TARDBP and a repeat expansion of C9ORF72. Patients carrying the p.A382T and the p.G295S mutations of TARDBP and the C9ORF72 repeat expansion shared distinct haplotypes across these loci. Patients with cooccurrence of C9ORF72 and TARDBP p.A382T missense mutation had a significantly lower age at onset and shorter survival. More than 40% of all cases on the island of Sardinia carry a mutation of an ALS-related gene, representing the highest percentage of ALS cases genetically explained outside of Scandinavia. Clinical phenotypes associated with different genetic mutations show some distinctive characteristics, but the heterogeneity between and among families carrying the same mutations implies that ALS manifestation is influenced by other genetic and nongenetic factors.