C. Gellera

High frequency of TARDBP gene mutations in Italian patients with amyotrophic lateral sclerosis

Recent studies identified rare missense mutations in amyotrophic lateral sclerosis (ALS) patients in the TARDBP gene encoding TAR DNA binding protein (TDP)‐43, the major protein of the ubiquitinated inclusions (UBIs) found in affected motor neurons (MNs). The aim of this study was to further define the spectrum of TARDBP mutations in a large cohort of 666 Italian ALS patients (125 familial and 541 sporadic cases). The entire coding region was sequenced in 281 patients, while in the remaining 385 cases only exon 6 was sequenced. In 18 patients, of which six are familial, we identified 12 different heterozygous missense mutations (nine novel) all locating to exon 6, which were absent in 771 matched controls. The c.1144G>A (p.A382T) variation was observed in seven patients, thus representing the most frequent TARDBP mutation in ALS. Analysis of microsatellites surrounding the TARDBP gene indicated that p.A382T was inherited from a common ancestor in 5 of the 7 patients. Altogether, the frequency of TARDBP gene mutations appears to be particularly high in Italian ALS patients compared to individuals of mainly Northern European origin (2.7% vs. 1%). Western blot analysis of lymphocyte extracts from two patients carrying the p.A382T and p.S393L TARDBP mutations showed the presence of lower molecular weight TDP‐43 bands, which were more abundant than observed in healthy controls and patients negative for TARDBP mutations. In conclusion, this report contributes to the demonstration of the causative role of the TARDBP gene in ALS pathogenesis and indicates that mutations may affect the stability of the protein even in nonneuronal tissues. Hum Mutat 0, 1–7, 2009.

The first reported generation of several induced pluripotent stem cell lines from homozygous and heterozygous Huntington's disease patients demonstrates mutation related enhanced lysosomal activity

Neuronal disorders, like Huntingtons disease (HD), are difficult to study, due to limited cell accessibility, late onset manifestations, and low availability of material. The establishment of an in vitro model that recapitulates features of the disease may help understanding the cellular and molecular events that trigger disease manifestations. Here, we describe the generation and characterization of a series of induced pluripotent stem (iPS) cells derived from patients with HD, including two rare homozygous genotypes and one heterozygous genotype. We used lentiviral technology to transfer key genes for inducing reprogramming. To confirm pluripotency and differentiation of iPS cells, we used PCR amplification and immunocytochemistry to measure the expression of marker genes in embryoid bodies and neurons. We also analyzed teratomas that formed in iPS cell-injected mice. We found that the length of the pathological CAG repeat did not increase during reprogramming, after long term growth in vitro, and after differentiation into neurons. In addition, we observed no differences between normal and mutant genotypes in reprogramming, growth rate, caspase activation or neuronal differentiation. However, we observed a significant increase in lysosomal activity in HD-iPS cells compared to control iPS cells, both during self-renewal and in iPS-derived neurons. In conclusion, we have established stable HD-iPS cell lines that can be used for investigating disease mechanisms that underlie HD. The CAG stability and lysosomal activity represent novel observations in HD-iPS cells. In the future, these cells may provide the basis for a powerful platform for drug screening and target identification in HD.

Ataxia with isolated vitamin E deficiency: neurological phenotype, clinical follow-up and novel mutations in TTPAgene in Italian families

Abstract.Ataxia with vitamin E deficiency (AVED) is a rare autosomal recessive neurodegenerative disorder due to mutations in the alpha-tocopherol transfer protein (TTPA) gene on chromosome 8q13. AVED patients have progressive spinocerebellar symptoms and markedly reduced plasma levels of vitamin E. We studied neurological phenotype at diagnosis, and long-term effect of vitamin E supplementation in 16 patients from 12 Italian families. The most common mutations were the 744delA and 513insTT. Two novel TTPA mutations were identified: a severe truncating mutation (219insAT) in a homozygous patient, and a Gly246Arg missense mutation (G246R) in a compound heterozygous patient. The missense mutation was associated with a mild and slowly progressive form of the disease. Vitamin E supplementation therapy allowed a stabilization of the neurological conditions in most of the patients. However, development of spasticity and retinitis pigmentosa was noted in a few patients during therapy. Prompt genetic characterization of AVED patients may allow an effective early treatment and an adequate genetic counseling.

Novel optineurin mutations in patients with familial and sporadic amyotrophic lateral sclerosis

Background Optineurin (OPTN), a causative gene of hereditary primary open-angle glaucoma, has been recently associated with amyotrophic lateral sclerosis (ALS) with mainly autosomal recessive, but also dominant, traits. To further define the contribution of OPTN gene in ALS, we performed a mutational screening in a large cohort of Italian patients. Methods A group of 274 ALS patients, including 161 familial (FALS) and 113 sporadic (SALS) cases, were screened for OPTN mutations by direct sequencing of its coding sequence. All patients fulfilled the El Escorial criteria for probable or definite ALS and were negative for mutations in SOD1, ANG, TARDBP and FUS/TLS genes. Results The genetic analysis revealed six novel variants in both FALS and SALS patients, all occurring in an heterozygous state. We identified three missense (c.844A→C p.T282P, c.941A→T p.Q314L, c.1670A→C p.K557T), one nonsense (c.67G→T p.G23X) and two intronic mutations (c.552+1delG, c.1401+4A→G). The intronic c.552+1delG variant determined a splicing defect as demonstrated by mRNA analysis. All mutations were absent in 280 Italian controls and over 6800 worldwide glaucoma patients and controls screened so far. The clinical phenotype of OPTN-mutated patients was heterogeneous for both age of onset and disease duration but characterised by lower-limb onset and prevalence of upper motor neuron signs. Conclusion In this cohort, OPTN mutations were present both in FALS (2/161), accounting for 1.2% cases, and in SALS patients (4/113), thereby extending the spectrum of OPTN mutations associated with ALS. The study further supports the possible pathological role of optineurin protein in motor neuron disease.

The complex clinical and genetic classification of inherited ataxias. II. Autosomal recessive ataxias

Abstract. Autosomal recessive ataxias are a heterogeneous group of rare neurodegenerative diseases characterized by early onset cerebellar ataxia associated with various neurologic, ophthalmolgic and systemic signs. In comparison with autosomal dominant ataxias, the group of recessive ataxias is less extensively characterized. In fact, only a few conditions have been genetically characterized. The pathogenesis of these forms is associated with a “loss of function” of specific cellular proteins involved in metabolic homeostasis, cell cycle, and DNA repair/protection processing. The two most common autosomal recessive ataxias, in European countries, are Friedreichs ataxia and ataxia telangiectasia. Other forms are much less frequent, and include ataxia with vitamin E deficiency, abetalipoproteinemia. Refsums disease, spastic ataxia, infantile onset spinocerebellar ataxia, and ataxia with oculomotor apraxia. These pathological conditions, although extremely rare, have nevertheless to be carefully considered in differential diagnosis, not only for correct nosographical classification, but particularly, for specific prognostic and therapeutic implications. Some of these diseases exhibit a peculiar regional distribution. An updated review of the clinical, genetic, and pathogenic aspects of recessive ataxias is presented. Specific management problems with respect to diagnosis and genetic counseling are discussed.

Paroxysmal movement disorders in GLUT1 deficiency syndrome

Glucose transporter type I deficiency syndrome ( GLUT1 DS OMIM No. 606777) is an inborn error of glucose transport characterized by seizures, developmental delay, spasticity, acquired microcephaly, and ataxia.1 In addition, in many patients paroxysmal events other than epilepsy have been described,2 but limited information is available regarding their phenomenology and classification. We report on clinical and genetic features of three unrelated Italian female patients with GLUT1 DS, diagnosed in early adulthood, all presenting with paroxysms of abnormal movements as the most relevant and disabling symptom.nn### Methods.nnMedical history was obtained from interviews of patients and their relatives and from medical records. Patients were diagnosed with GLUT1 DS according to the established clinical and biochemical criteria and confirmed by genetic testing.1 Patients and healthy relatives’ DNA was extracted from venous peripheral blood lymphocytes according to standard procedures. All exons and intron-exons boundaries (exon 1–10) of the GLUT1 gene were tested for mutations by direct sequence analysis using an automated sequencing system (ABI Prism 3100 Genetic Analyzer; Applied Biosystems). Real time PCR was performed (7300 Real-Time PCR System, …

Superoxide dismutase gene mutations in Italian patients with familial and sporadic amyotrophic lateral sclerosis: identification of three novel missense mutations

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder affecting motor neurons. The majority of the patients are sporadic cases (SALS), while 5-10% of the patients have a family history of ALS (familial ALS or FALS). Mutations in the gene coding for cytoplasmic Cu/Zn superoxide dismutase (SOD1) have been identified in about 20% of FALS cases. We found SOD1-gene mutations in five of 34 unrelated FALS, and in two of 44 SALS patients. Three FALS patients carried the previously described A4V (two cases) and L84F mutations (one case), while two FALS patients carried new missense mutations: a G12R substitution in exon 1, and a F45C substitution in exon 2, respectively. The newly identified mutations were both associated with a slowly progressive disease course. Two SALS patients carried the homozygous D90A and the heterozygous I113T mutation, respectively. In addition, in one SALS patient we identified an A95T amino acid substitution, that is apparently a non-pathogenic SOD1 variant. Our study increases the number of ALS-associated SOD1 gene mutations.

Relative Frequencies of CAG Expansions in Spinocerebellar Ataxia and Dentatorubropallidoluysian Atrophy in 116 Italian Families

Two hundred and forty-eight patients from 116 Italian families with dominant ataxia were studied for CAG expansion within SCA1, 2, 3, 6, 7 (spinocerebellar ataxia) and DRPLA (dentatorubropallidoluysian atrophy) genes. Fifty-six percent of the families originated from Southern, 19% from Central and 25% from Northern Italy. SCA2 was the commonest mutation, accounting for 47% of the families, followed by SCA1 (24%), SCA6 (2%), SCA7 (2%) and DRPLA (1%). No SCA3 family was found. Twenty-four percent of the families carried a still unidentified mutation. When occurrence of mutations was evaluated according to the geographic origin, SCA1 was the commonest in Northern (72%), whereas SCA2 was prevalent (63%) in Southern Italy. The number of CAG repeats in SCA1 normal alleles was higher in Northern than in Central-Southern Italy.

Age and founder effect of SOD1 A4V mutation causing ALS

Background: The alanine to valine mutation at codon 4 (A4V) of SOD1 causes a rapidly progressive dominant form of amyotrophic lateral sclerosis (ALS) with exclusively lower motor neuron disease and is responsible for 50% of SOD1 mutations associated with familial ALS in North America. This mutation is rare in Europe. The authors investigated the origin (geographic and time) of the A4V mutation. Methods: Several cohorts were genotyped: North American patients with confirmed A4V mutation (n = 54), Swedish (n = 3) and Italian (n = 6) A4V patients, patients with ALS with SOD1 non-A4V mutations (n = 66) and patients with sporadic ALS (n = 96), healthy white (n = 96), African American (n = 17), Chinese (n = 53), Amerindian (n = 11), and Hispanic (n = 12) subjects. High-throughput SNP genotyping was performed using Taqman assay in 384-well format. A novel biallelic CA repeat in exon 5 of SOD1, tightly linked to A4V, was genotyped on sequencing gels. Association statistics were estimated using Haploview. p Values less than 0.05 were considered significant. Age of A4V was estimated using a novel method based on r2 degeneration with genetic distance and a Bayesian method incorporated in DMLE+. Results: A single haplotype of 10 polymorphisms across a 5.86-cM region was associated with A4V (p = 3.0e-11) when white controls were used, suggesting a founder effect. The strength of association of this haplotype progressively decreased when African American, Chinese, Hispanic, and Amerindian subjects were used as controls. The associated European haplotype was different from the North American haplotype, indicating two founder effects for A4V (Amerindian and European). The estimated age of A4V with the r2 degeneration method was 458 ± 59 years (range 398–569) and in agreement with the Bayesian method (554–734 years with 80–90% posterior probability). Conclusions: North American SOD1 alanine to valine mutation at codon 4 descended from two founders (Amerindian and European) 400–500 years ago.

Spinocerebellar ataxia type 17 (SCA17): Oculomotor phenotype and clinical characterization of 15 Italian patients

SCA17 is a rare type of autosomal dominant spinocerebellar ataxia caused by a CAG/CAA expansion in the gene encoding the TATA-binding protein (TBP).We screened for triplet expansion in the TBP gene 110 subjects with progressive cerebellar ataxia and 94 subjects with Huntington-like phenotype negative at specific molecular tests. SCA17 mutation-positive subjects were found in both groups of patients. Expanded alleles with ≥ 44 CAG/CAA repeats were identified in 11 individuals and in 4 non-symptomatic relatives. Eleven de novo diagnosed patients and four patients previously reported underwent extensive clinical, neuroradiological and oculographic examination. Cerebellar signs and symptoms were present in all cases; 80% of the patients had mild to severe cognitive deficits; 66% of patients showed choreic movements; pyramidal signs, bradykinesia and dystonia were observed in approx 50% of the cases. MRI demonstrated cortical and cerebellar atrophy in all patients, whereas neurophysiological examination excluded signs of peripheral nervous system involvement. Oculographic examinations were performed in 9 out of 15 patients and showed a distinct pattern of oculomotor abnormalities, characterized by impairment of smooth pursuit, defects in the saccade accuracy, normal saccade velocity, hyperreflexia of vestibuloocular reflexes, and absence of nystagmus.In summary, this study presents one of the largest series of SCA17 patients in Europe. In our group of patients, SCA17 represents the third most frequent SCA genotype. Our clinical data confirm the large variability in SCA17 phenotypic presentation, and indicate that a peculiar combination of neuroradiological, electrophysiological and oculomotor findings is recognizable in SCA17.