Francesca Bertola

IDUA mutational profiling of a cohort of 102 European patients with mucopolysaccharidosis type I: identification and characterization of 35 novel α-L-iduronidase (IDUA) alleles

Mutational analysis of the IDUA gene was performed in a cohort of 102 European patients with mucopolysaccharidosis type I. A total of 54 distinct mutant IDUA alleles were identified, 34 of which were novel including 12 missense mutations, 2 nonsense mutations, 12 splicing mutations, 5 micro‐deletions, 1 micro‐duplication 1 translational initiation site mutation, and 1 ‘no‐stop’ change (p.X654RextX62). Evidence for the pathological significance of all novel mutations identified was sought by means of a range of methodological approaches, including the assessment of evolutionary conservation, RT‐PCR/in vitro splicing analysis, MutPred analysis and visual inspection of the 3D‐model of the IDUA protein. Taken together, these data not only demonstrate the remarkable mutational heterogeneity characterizing type 1 mucopolysaccharidosis but also illustrate our increasing ability to make deductions pertaining to the genotype‐phenotype relationship in disorders manifesting a high degree of allelic heterogeneity.

Analysis of vesicular monoamine transporter 2 polymorphisms in Parkinson’s disease

Generation of reactive oxygen species during dopamine (DA) oxidation could be one of the factors leading to the selective loss of nigral dopaminergic neurons in Parkinson’s disease (PD). Vesicular monoamine transporter type 2 (VMAT2) proteins in nerve terminals uptake dopamine into synaptic vesicles, preventing its cytoplasmic accumulation and toxic damage to nigral neurons. Polymorphisms in VMAT2 gene and in its regulatory regions might therefore serve as genetic risk factors for PD. In the present study, we have analyzed 8 single-nucleotide polymorphisms (SNPs) located within/around the VMAT2 gene for association with PD in an Italian cohort composed of 704 PD patients and 678 healthy controls. Among the 8 SNPs studied, only the 2 located within the promoter region (rs363371 and rs363324) were significantly associated with PD. In the dominant model, odds ratios were 0.72 (95% confidence interval [CI]: 0.6–0.9, p < 0.005) for rs363371 and 0.76 (95% CI: 0.6–0.9, p = 0.01) for rs363324; in the additive model, odds ratios were 0.78 (95% CI: 0.65–0.94, p = 0.008) for rs363371 and 0.85 (95% CI: 0.7–20.92, p = 0.04) for rs363324. There were no significant relationships between the remaining SNPs (rs363333, rs363399, rs363387, rs363343, rs4752045, and rs363236) and the risk of sporadic PD in any genetic model. This study adds to the previous evidence suggesting that variability in VMAT2 promoter region may confer a reduced risk of developing PD, presumably via mechanisms of gene overexpression.

Novel mutations of the ferroportin gene (SLC40A1) : analysis of 56 consecutive patients with unexplained iron overload

The aim of this study was to search for SLC40A1 mutations in iron overloaded patients, which tested negative for HFE mutations and other iron‐related genes. After a careful differential diagnosis, we selected 56 patients with unexplained iron overload whose phenotype could suggest the ferroportin disease. Iron overload was assessed by liver biopsy or by superconducting quantum interference device. SLC40A1 exons and intron–exon boundaries were amplified by polymerase chain reaction and sequenced. We also evaluated the presence of the insulin‐resistance hepatic iron overload and of non‐alcoholic fatty liver disease. Iron status was assessed in 44 families. We identified two novel mutations (D157N and V72F) at the heterozygous state in two probands. Phenotype heterogeneity was observed in both families, suggesting variable penetrance and expression. Including the two affected ones, 25 of the 44 families (57%) available for the iron study had one or more relatives with increased serum iron indices. Our findings not only suggest that the presence of major alterations of serum iron parameters in probands’ relatives is a main criteria to improve the power of the genetic testing for ferroportin disease but also indicate that a number of patients exists in which the etiology of iron overload remains still undefined.

Homozygous deletion of HFE: the Sardinian hemochromatosis?

To the editor: Type 1 hemochromatosis is generally due to homozygous p.C282Y mutation in HFE .[1][1],[2][2] We report the case of a young woman with a classical hemochromatosis phenotype due to a homozygous deletion in the 6p chromosome region containing HFE . The proband is a 29-year-old woman of

Higher than expected progranulin mutation rate in a case series of Italian FTLD patients.

To the Editor: Frontotemporal Lobar Degeneration (FTLD) recognizes a high familial incidence, with up to 50% of patients reporting a positive family history for cognitive impairment. Mutations within the progranulin (PGRN) gene have been reported to be a major cause of FTLD worldwide, accounting for 5%-10% of sporadic FTLD cases, and for 20%-25% of the familial ones. Nevertheless, Borroni and colleagues, recently published a study based on an Italian sample, challenging these data, and supporting a lower frequency of PGRN mutations in 243 FTLD patients, being 1.64% the overall value, and 6.6% when separately analyzing only the familial cases. Considering this discrepancy, we decided to assess the incidence of PGRN and tau (MAPT) mutations in our FTLD patient population (MonzaBrianza area, Northern Italy). We consecutively recruited from our Memory Clinic 22 FTLD outpatients diagnosed according to the ‘‘Neary’’ criteria (2 familial and 20 sporadic cases, ie, without family history of dementia), testing them for both PGRN and MAPT mutations. The clinical phenotype encompassed mainly the frontal behavioral subtype of FTLD (16 cases), followed by Progressive Non Fluent Aphasia (PNFA) (4 cases), and by semantic dementia (2 cases); mean age at disease onset (±SD) was 64 years (±5.6). The familial cases were affected, one by the behavioral variant, and the other by semantic dementia; for both patients, several related family members had been clinically diagnosed as having either FTLD, or the frontal variant of Alzheimer’s disease. All of our patients were found to be negative for MAPT mutations. On the other hand, 2 FTLD patients (the behavioral familial case and 1 sporadic PNFA case) were found positive as heterozygous carriers of the c.813_816delCACT (exon 7) PGRN mutation, corresponding to 9% of cases overall, and 5% of (apparently) sporadic cases. The age of onset for the familial positive case was 63 years (current age 70), whereas for the sporadic positive case was 61 years (the patient died at age 66). This mutation has been recently identified for the first time in 2 independent Italian pedigrees with clinical presentations ranging from FTLD to corticobasal syndrome. Thus, our finding further supports the idea that such a mutation might indeed represent a novel, significant genetic determinant of FTLD in Northern Italy. Moreover, here we report for the first time the occurrence of this mutation in an apparently sporadic setting. Our report refers to a few patients, all originating from the same, relatively small geographical area, so that we cannot exclude that the present data might be biased by the limited sample size and they need to be confirmed. Nevertheless, our data suggest that, at least in our area, the PGRN mutation rate might be higher than expected for an Italian case series, and more similar to that reported worldwide, confirming that searching for PGRN mutations might be useful even in sporadic FTLD cases. Note: For both PGRN and MAPT, several polymorphisms were identified in our population. PGRN: IVS2+21G>A (n=6 patients); IVS2 +7G>A (n=2, novel finding); IVS347_-46insGTCA (n=8); c.384T>C (n=1); IVS4+24G>A (n=10); IVS7 +7G>A (n=4); 3’UTR+78C>T (n=2); p.G23 (n=1). MAPT: p. A227 (n=8); p.N255 (n=9); p.P270 (n=1); IVS11+34G>A (n=12).

First report of PSEN2 mutation presenting as posterior cortical atrophy.

Posterior cortical atrophy (PCA) is a neurodegenerative dementing disorder affecting mainly visuospatial and visuoperceptual skills and showing elements of Balint and Gerstmann’s syndrome. Atrophy of parieto-occipital areas is usually evident at neuroimaging. The underlying histopathology is Alzheimer disease (AD) in at least 80% of the cases.1 In contrast to AD, the genetic bases of PCA are still quite elusive and only 4 cases have been described so far, with highly heterogenous mutations, albeit all with an autosomal dominant pattern of transmission. Two genetic PCA cases track back to 2 different AD-related presenilin 1 mutations: I211M and Q223R.2,3 The third report relates to an entire PCA family harboring a 5-octarepeat motif insertional mutation into the N-terminal region of the prion protein gene.4 Finally, a PCA patient carrying the V363I mutation in the microtubule-associated protein tau gene has been reported very recently.5 Herein, we describe the first PCA case due to a rare mutation within the presenilin 2 (PSEN2) gene.

Association analysis of PARP1 polymorphisms with Parkinson's disease.

Alpha-synuclein accumulation in intracellular inclusions, oxidative stress and microglia-mediated inflammation in the substantia nigra are crucial events in the pathogenesis of Parkinson’s disease (PD). Poly (ADP-ribose) polymerase-1 (PARP1), a DNA-binding enzyme and transcriptional regulator, plays an important role in modulating the cellular response to oxidative stress, inflammatory stimuli, and in apoptotic cell death. Inhibition of PARP1 results in significant neuroprotection in PD animal models; moreover PARP1 has a physiological role in the regulation of alpha-synuclein expression. A previous study had demonstrated that variants located within the PARP1 gene promoter reduce the risk of PD and delay the disease age at onset. In light of these data, we carried out an association study to investigate whether variability within this gene is associated with PD risk and disease age at onset in an Italian cohort composed of 600 PD patients and 592 healthy controls. To this purpose, we used a comprehensive tag SNP approach spanning the entire gene and the upstream and downstream regions. We did not detect any significant association of the PARP1 gene with PD either at genotypic or haplotypic level; none of the 11 genotyped SNPs was significantly associated with PD age at onset. We conclude that, despite previous evidence, PARP1 is not a susceptibility gene for PD in our population.

Forgetful and robotic: tap on a gene!

A 41 year-old male patient with a two-year history of cognitive impairment involving episodic memory and apraxic features came to our attention. Besides global and multidomain compromised cognition (MMSE: 21/30), spastic paraparesis with increased deep tendon reflexes and sustained bilateral ankle clonus was evident at neurological examination. Past medical history was significant only for episodic migraine without aura since the age of 20. Family history was negative for either neurological or psychiatric disorders. HIV and HTLV-1 virus serology were negative. A brain MR scan showed mild white matter disease, particularly marked in the left fronto-temporal area and biparietal cortical atrophy (Fig. 1). A lumbar puncture was performed and genetic testing consequently asked for,