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SCA12 is an autosomal dominant cerebellar ataxia characterized by onset in the fourth decade of life with action tremor of arms and head, mild ataxia, dysmetria, and hyperreflexia. The disease is caused by an expansion of ≥51 CAGs in the 5′ region of the brain- specific phosphatase 2 regulatory subunit B-beta isoform ( PPP2R2B) gene. SCA12 is very rare, except for a single ethnic group in India. We screened 159 Italian ataxic patients for SCA12 and identified two families that segregated an expanded allele of 57 to 58 CAGs, sharing a common haplotype. The age at onset, phenotype, and variability of symptoms were compatible with known cases. In one family, the disease was apparently sporadic due to possible incomplete penetrance and/or late age at onset. Our data indicate that SCA12 is also present in Italian patients, and its genetic testing should be applied to both sporadic and familial ataxias. © 2010 Movement Disorder Society [ABSTRACT FROM AUTHOR]

Ataxia is a frequently reported symptom in prion diseases (PD) and it is characteristic of Gerstmann-Sträussler-Scheinker syndrome (GSS), a genetic PD mainly related to the P102L mutation in the PRNP gene. Our aim was to screen for the P102L and other six known PRNP gene mutations (P105L, A117V, Y145X, E200K, D202N, and V210I) a group of 206 consecutive patients diagnosed with adult-onset cerebellar ataxia of unknown origin. The patients, negative for the most common acquired and genetic forms, were analyzed using a combination of restriction endonuclease digestion and pyrosequencing; eight, affected by ataxia and cognitive dysfunction, were also sequenced for the PRNP gene. One patient resulted to be heterozygous for the P102L mutation. Retrospectively, the clinical picture was consistent with a 'classical' GSS phenotype. In conclusion, the screening for the P102L mutation, or even the sequencing of the PRNP gene should be taken in consideration in patients with late-onset ataxia (>50 years). © 2008 Movement Disorder Society [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to an article about mutations in the POLG1 gene as irrelevant cause of cerebellar ataxia in Italy by Claudia Cagnoli and colleagues in the 2006 issue.

Background: SCA28 is an autosomal dominant ataxia associated with AFG3L2 gene mutations. We performed a whole genome expression profiling using lymphoblastoid cell lines (LCLs) from four SCA28 patients and six unrelated healthy controls matched for sex and age. Methods: Gene expression was evaluated with the Affymetrix GeneChip Human Genome U133A 2.0 Arrays and data were validated by real-time PCR. Results: We found 66 genes whose expression was statistically different in SCA28 LCLs, 35 of which were up-regulated and 31 down-regulated. The differentially expressed genes were clustered in five functional categories: (1) regulation of cell proliferation; (2) regulation of programmed cell death; (3) response to oxidative stress; (4) cell adhesion, and (5) chemical homeostasis. To validate these data, we performed functional experiments that proved an impaired SCA28 LCLs growth compared to controls (p < 0.005), an increased number of cells in the G0/G1 phase (p < 0.001), and an increased mortality because of apoptosis (p < 0.05). We also showed that respiratory chain activity and reactive oxygen species levels was not altered, although lipid peroxidation in SCA28 LCLs was increased in basal conditions (p < 0.05). We did not detect mitochondrial DNA large deletions. An increase of TFAM, a crucial protein for mtDNA maintenance, and of DRP1, a key regulator of mitochondrial dynamic mechanism, suggested an alteration of fission/fusion pathways. Conclusions: Whole genome expression profiling, performed on SCA28 LCLs, allowed us to identify five altered functional categories that characterize the SCA28 LCLs phenotype, the first reported in human cells to our knowledge. [ABSTRACT FROM AUTHOR]

Allele-specific silencing by RNA interference (ASP-siRNA) holds promise as a therapeutic strategy for downregulating a single mutant allele with minimal suppression of the corresponding wild-type allele. This approach has been effectively used to target autosomal dominant mutations and single nucleotide polymorphisms linked with aberrantly expanded trinucleotide repeats. Here, we propose ASP-siRNA as a preferable choice to target duplicated disease genes, avoiding potentially harmful excessive downregulation. As a proof-of-concept, we studied autosomal dominant adult-onset demyelinating leukodystrophy (ADLD) due to lamin B1 (LMNB1) duplication, a hereditary, progressive and fatal disorder affecting myelin in the CNS. Using a reporter system, we screened the most efficient ASP-siRNAs preferentially targeting one of the alleles at rs1051644 (average minor allele frequency: 0.45) located in the 3' untranslated region of the gene. We identified four siRNAs with a high efficacy and allele-specificity, which were tested in ADLD patient-derived fibroblasts. Three of the small interfering RNAs were highly selective for the target allele and restored both LMNB1 mRNA and protein levels close to control levels. Furthermore, small interfering RNA treatment abrogates the ADLD-specific phenotypes in fibroblasts and in two disease-relevant cellular models: murine oligodendrocytes overexpressing human LMNB1, and neurons directly reprogrammed from patients' fibroblasts. In conclusion, we demonstrated that ASP-silencing by RNA interference is a suitable and promising therapeutic option for ADLD. Moreover, our results have a broad translational value extending to several pathological conditions linked to gene-gain in copy number variations. [ABSTRACT FROM AUTHOR]

Abstract Spinocerebellar ataxia 28 is an autosomal dominant neurodegenerative disorder caused by missense mutations affecting the proteolytic domain of AFG3L2, a major component of the mitochondrial m -AAA protease. However, little is known of the underlying pathogenetic mechanisms or how to treat patients with SCA28. Currently available Afg3l2 mutant mice harbour deletions that lead to severe, early-onset neurological phenotypes that do not faithfully reproduce the late-onset and slowly progressing SCA28 phenotype. Here we describe production and detailed analysis of a new knock-in murine model harbouring an Afg3l2 allele carrying the p.Met665Arg patient-derived mutation. Heterozygous mutant mice developed normally but adult mice showed signs of cerebellar ataxia detectable by beam test. Although cerebellar pathology was negative, electrophysiological analysis showed a trend towards increased spontaneous firing in Purkinje cells from heterozygous mutants with respect to wild-type controls. As homozygous mutants died perinatally with evidence of cardiac atrophy, for each genotype we generated mouse embryonic fibroblasts (MEFs) to investigate mitochondrial function. MEFs from mutant mice showed altered mitochondrial bioenergetics, with decreased basal oxygen consumption rate, ATP synthesis and mitochondrial membrane potential. Mitochondrial network formation and morphology was altered, with greatly reduced expression of fusogenic Opa1 isoforms. Mitochondrial alterations were also detected in cerebella of 18-month-old heterozygous mutants and may be a hallmark of disease. Pharmacological inhibition of de novo mitochondrial protein translation with chloramphenicol caused reversal of mitochondrial morphology in homozygous mutant MEFs, supporting the relevance of mitochondrial proteotoxicity for SCA28 pathogenesis and therapy development. Graphical abstract Unlabelled Image Highlights • We generated a knock-in mouse model of SCA28 harbouring a p.Met665Arg -Afg3l2 allele. • Homozygous mutants died perinatally with evidence of cardiac atrophy. • Heterozygous mice developed normally but presented late-onset cerebellar ataxia. • MEFs showed altered mitochondrial bioenergetics and dynamics. • Proteotoxicity is suggested to be responsible for SCA28 pathogenesis. [ABSTRACT FROM AUTHOR]

Karyotyping and aCGH are routinely used to identify genetic determinants of major congenital malformations (MCMs) in fetal deaths or terminations of pregnancy after prenatal diagnosis. Pathogenic rearrangements are found with a variable rate of 9-39% for aCGH. We collected 33 fetuses, 9 with a single MCM and 24 with MCMs involving 2-4 organ systems. aCGH revealed copy number variants in 14 out of 33 cases (42%). Eight were classified as pathogenic which account for a detection rate of 24% (8/33) considering fetuses with 1 or more MCMs and 33% (8/24) taking into account fetuses with multiple malformations only. Three of the pathogenic variants were known microdeletion syndromes (22q11.21 deletion, central chromosome 22q11.21 deletion, and TAR syndrome) and 5 were large rearrangements, adding up to >11 Mb per subject and comprising strong phenotype-related genes. One of those was a de novo complex rearrangement, and the remaining 4 duplications and 2 deletions were 130-900 kb in size, containing 1-7 genes, and were classified as variants of unknown clinical significance. Our study confirms aCGH as a powerful technique to ascertain the genetic etiology of fetal major congenital malformations. © 2015 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Mutations in COL4A1 , encoding one of the six collagen type IV proteins, cover a wide spectrum of autosomal dominant overlapping phenotypes including porencephaly, small-vessel disease and hemorrhagic stroke, leukoencephalopathy, hereditary angiopathy with nephropathy, aneurysms and muscle cramp (HANAC) syndrome, and Walker–Warburg syndrome. Over 50 mutations are known, mainly being missense changes. Intra- and inter-familial variability has been reported. We studied two Italian families in which the proband had a clinical diagnosis of COL4A1 -related disorder. We found two novel mutations (c.1249G>C; p.Gly417Arg and c.2662G>C; p.Gly888Arg). Both involved highly conserved amino acids and were predicted as being deleterious by bioinformatics tools. The c.1249G>C (p.Gly417Arg) segregated in four subjects with variable neurological phenotypes, namely leukoencephalopathy with muscle symptoms, brain small-vessel disease, and mild infantile encephalopathy. A fourth case was a carrier of the mutation without any neurological symptoms and an MRI with a specific white matter anomaly. The c.2662G>C (p.Gly888Arg) mutation was de novo in the proband. After a temporary motor impairment at age 14, the subject complained of mild imbalance at age 30, during the third trimester of her twin pregnancy, when an anomaly of the left brain hemisphere was documented in one fetus. Both her male dizygotic twins presented a severe motor delay, early convulsions, and leukoencephalopathy, and were carriers of the mutation. In summary, we confirm that high intra-familial variability of COL4A1 mutations with very mild phenotypes, the apparent incomplete penetrance, and de novo changes may become a “dilemma” for clinicians and genetic counselors. [ABSTRACT FROM AUTHOR]

Autosomal recessive inherited ataxias are a growing group of genetic disorders. We report two Italian siblings presenting in their mid-50s with difficulty in walking, dysarthria and progressive cognitive decline. Visual loss, ascribed to glaucoma, manifested a few years before the other symptoms. Brain MRI showed severe cerebellar atrophy, prevalent in the vermis, with marked cortical atrophy of both hemispheres. Exome sequencing identified a novel homozygous mutation (c.935G > A;p.Ser312Asn) in the ceroid neuronal lipofuscinosis type 5 gene ( CLN5). Bioinformatics predictions and in vitro studies showed that the mutation was deleterious and likely affects ER-lysosome protein trafficking. Our findings support CLN5 hypomorphic mutations cause autosomal recessive cerebellar ataxia, confirming other reports showing CLN mutations are associated with adult-onset neurodegenerative disorders. We suggest CLN genes should be considered in the molecular analyses of patients presenting with adult-onset autosomal recessive cerebellar ataxia. [ABSTRACT FROM AUTHOR]

In spinocerebellar ataxias, age at onset is negatively correlated with the size of causative (CAG)n expansions. In an analysis of 1255 patients, Tezenas du Montcel et al. identify threshold effects, interactions between alleles in trans, and relationships between (CAG)n-containing genes. Partial replication is achieved in independent Caucasian and Asian samples.Polyglutamine-coding (CAG)n repeat expansions in seven different genes cause spinocerebellar ataxias. Although the size of the expansion is negatively correlated with age at onset, it accounts for only 50–70% of its variability. To find other factors involved in this variability, we performed a regression analysis in 1255 affected individuals with identified expansions (spinocerebellar ataxia types 1, 2, 3, 6 and 7), recruited through the European Consortium on Spinocerebellar Ataxias, to determine whether age at onset is influenced by the size of the normal allele in eight causal (CAG)n-containing genes (ATXN1–3, 6–7, 17, ATN1 and HTT). We confirmed the negative effect of the expanded allele and detected threshold effects reflected by a quadratic association between age at onset and CAG size in spinocerebellar ataxia types 1, 3 and 6. We also evidenced an interaction between the expanded and normal alleles in trans in individuals with spinocerebellar ataxia types 1, 6 and 7. Except for individuals with spinocerebellar ataxia type 1, age at onset was also influenced by other (CAG)n-containing genes: ATXN7 in spinocerebellar ataxia type 2; ATXN2, ATN1 and HTT in spinocerebellar ataxia type 3; ATXN1 and ATXN3 in spinocerebellar ataxia type 6; and ATXN3 and TBP in spinocerebellar ataxia type 7. This suggests that there are biological relationships among these genes. The results were partially replicated in four independent populations representing 460 Caucasians and 216 Asian samples; the differences are possibly explained by ethnic or geographical differences. As the variability in age at onset is not completely explained by the effects of the causative and modifier sister genes, other genetic or environmental factors must also play a role in these diseases. [ABSTRACT FROM PUBLISHER]

A recently described genetic disorder has been associated with 13q12.3 microdeletion spanning three genes, namely, KATNAL1, LINC00426, and HMGB1. Here, we report a new case with similar clinical features that we have followed from birth to 5 years old. The child carried a complex rearrangement with a double translocation: 46,XX,t(7;13)(p15;q14),t(11;15)(q23;q22). Array-CGH identified a de novo microdeletion at 13q12.2q13.1 spanning 3-3.4 Mb and overlapping 13q12.3 critical region. Clinical features resembling those reported in the literature confirm the existence of a distinct 13q12.3 microdeletion syndrome and provide further evidence that is useful to characterize its phenotypic expression during the 5 years of development. [ABSTRACT FROM AUTHOR]

This paper reports a case of recurrent miscarriage in a patient affected by a variant phenotype of sperm macrocephaly syndrome (SMS). SMS is usually related to specific sperm characteristics (large head, multiple tail) and homozygous mutations in the aurora kinase C gene (AURKC). However, the present case observed large-headed spermatozoa with no flagellar abnormalities and no mutations detectable by AURKC sequencing. Furthermore, the patient had repeatedly conceived by intracytoplasmic sperm injection, but pregnancy always aborted. This study performed morphological analysis (Papanicotau staining), annexin V/propidium iodide staining, sperm chromatin structure assay (SCSA), fluorescence in-situ hybridization (FISH) and transmission electron microscopy. This study observed large-headed, mono-tailed, mono-centriolar spermatozoa characterized by abnormal chromatin and swollen mitochondria. SCSA revealed a high ratio of late apoptotic cells with fairly intact amount of DNA. The FISH analysis showed 100% disomy rate. As far as is known, this is the first study to include gene sequencing, TEM, cytogenetic analysis and sperm DNA fragmentation in a case of SMS and also to report recurrent miscarriage related to this specific condition. SMS may be associated with important abnormalities of the sperm subcellular structure and with disomy even in the absence of mutations in the AURKC coding sequence. Sperm macrocephaly syndrome (SMS) is a rare condition that affects spermatozoa and is related to infertility. It is characterized by a specific phenotype of large-headed, multi-tailed spermatozoa with an abnormal chromosomal status. A very few pregnancies have been obtained so far in SMS patients by means of IVF procedures. We present a case of SMS that differs from the classical syndrome as we observed large-headed spermatozoa without tail abnormalities. The affected patient had achieved three pregnancies following IVF, but art aborted. We carried out a detailed examination of the patient's spermatozoa - morphological, cytogenetic, DNA fragmentation and ultrastructural analysis - and we observed that his spermatozoa are characterized by a large head whose texture appears apoptotic, a single tail and a midpiece whose mitochondria appear swollen. The DNA content within the spermatozoa was altered, as well as the chromosomal status, suggesting that some error must have occurred during spermatogenesis. Interestingly, the genetic sequencing of the specific gene usually related to SMS syndrome (AURKC) revealed no mutations in our patient, suggesting that other genes may be involved in determining this syndrome. As far as is known, this is the first study in which spermatozoa of a SMS patient have been observed using morphological analysis, ultrastructural analysis, cytogenetic analysis and sperm DNA fragmentation analysis together. Moreover, it is believed that this is first report of recurrent miscarriage due to this specific syndrome. [ABSTRACT FROM AUTHOR]

Autosomal dominant spinocerebellar ataxias (SCAs) are genetically heterogeneous neurological disorders characterized by cerebellar dysfunction mostly due to Purkinje cell degeneration. Here we show that AFG3L2 mutations cause SCA type 28. Along with paraplegin, which causes recessive spastic paraplegia, AFG3L2 is a component of the conserved m-AAA metalloprotease complex involved in the maintenance of the mitochondrial proteome. We identified heterozygous missense mutations in five unrelated SCA families and found that AFG3L2 is highly and selectively expressed in human cerebellar Purkinje cells. m-AAA–deficient yeast cells expressing human mutated AFG3L2 homocomplex show respiratory deficiency, proteolytic impairment and deficiency of respiratory chain complex IV. Structure homology modeling indicates that the mutations may affect AFG3L2 substrate handling. This work identifies AFG3L2 as a novel cause of dominant neurodegenerative disease and indicates a previously unknown role for this component of the mitochondrial protein quality control machinery in protecting the human cerebellum against neurodegeneration. [ABSTRACT FROM AUTHOR]

Spinocerebellar ataxia type15 (SCA15) is a pure ataxia characterized by very slow progression. Only seven families have been identified worldwide, in which partial deletions and a missense mutation of the inositol triphosphate receptor type I gene ( ITPR1) have been reported. We examined a four-generation Italian family segregating an autosomal dominant cerebellar ataxia, in which linkage analysis was positive for the SCA15 locus. We performed a genomic real-time polymerase chain reaction to search for ITPR1 gene deletions in this family and in 60 SCA index cases negative for mutations in the SCA1–3, 6–8, 10, 12, and dentatorubral-pallidoluysian atrophy genes. The deleted segments were characterized using a custom array comparative genomic hybridization analysis. We have identified two families with an ITPR1 gene deletion: in one, the deletion involved ITPR1 only, while in the other both sulfatase-modifying factor 1 and ITPR1. Clinical data of ten patients and brain MRI (available for six) showed that the phenotype substantially overlapped known SCA15 cases, but we also noted buccolingual dyskinesias, facial myokymias, and pyramidal signs never reported in SCA15. ITPR1 expression analysis of two deleted cases showed a half dose. Our results further support ITPR1 gene as causative of SCA15. The families reported show that SCA15 is present in Italy and has a greater variability in the age at onset and clinical features than previously reported. We propose that the search for ITPR1 deletions is mandatory in the clinical hypothesis of SCA15 and that ITPR1-reduced expression in blood may be a useful marker to identify SCA15 patients harboring genomic deletions and possibly point mutations causing reduction of mRNA level. [ABSTRACT FROM AUTHOR]

Ataxia is a frequently reported symptom in prion diseases (PD) and it is characteristic of Gerstmann-Sträussler-Scheinker syndrome (GSS), a genetic PD mainly related to the P102L mutation in the PRNP gene. Our aim was to screen for the P102L and other six known PRNP gene mutations (P105L, A117V, Y145X, E200K, D202N, and V210I) a group of 206 consecutive patients diagnosed with adult-onset cerebellar ataxia of unknown origin. The patients, negative for the most common acquired and genetic forms, were analyzed using a combination of restriction endonuclease digestion and pyrosequencing; eight, affected by ataxia and cognitive dysfunction, were also sequenced for the PRNP gene. One patient resulted to be heterozygous for the P102L mutation. Retrospectively, the clinical picture was consistent with a "classical" GSS phenotype. In conclusion, the screening for the P102L mutation, or even the sequencing of the PRNP gene should be taken in consideration in patients with late-onset ataxia (>50 years). [ABSTRACT FROM AUTHOR]

Microphthalmia with limb anomalies (MLA, OMIM, 206920) is a rare autosomal-recessive disease caused by biallelic pathogenic variants in the SMOC1 gene. It is characterized by ocular disorders (microphtalmia or anophtalmia) and limb anomalies (oligodactyly, syndactyly, and synostosis of the 4th and 5th metacarpals), variably associated with long bone hypoplasia, horseshoe kidney, venous anomalies, vertebral anomalies, developmental delay, and intellectual disability. Here, we report the case of a woman who interrupted her pregnancy after ultrasound scans revealed a depression of the frontal bone, posterior fossa anomalies, cerebral ventricular enlargement, cleft spine involving the sacral and lower-lumbar vertebrae, and bilateral microphthalmia. Micrognathia, four fingers in both feet and a slight tibial bowing were added to the clinical picture after fetal autopsy. Exome sequencing identified two variants in the SMOC1 gene, each inherited from one of the parents: c.709G>T - p.(Glu237*) on exon 8 and c.1223G>A - p.(Cys408Tyr) on exon 11, both predicted to be pathogenic by different bioinformatics software. Brain histopathology showed an abnormal cortical neuronal migration, which could be related to the SMOC1 protein function, given its role in cellular signaling, proliferation and migration. Finally, we summarize phenotypic and genetic data of known MLA cases showing that our case has some unique features (Chiari II malformation; focal neuropathological alterations) that could be part of the variable phenotype of SMOC1-associated diseases. [ABSTRACT FROM AUTHOR]