PolyQ Database-an integrated database on polyglutamine diseases.

Polyglutamine (polyQ) diseases are neurodegenerative disorders caused by abnormally expanded Cytosine, Adenine, Guanine (CAG) triplet repeat sequences in the coding region of otherwise unrelated genes. Until now, nine different polyQ diseases have been described: Huntington's disease, dentatorubral-pallidoluysian atrophy, spinal and bulbar muscular atrophy and six types of spinocerebellar ataxias-1, 2, 3, 6, 7 and 17. The pathogenic expansion translates into an aberrant tract of glutamines in the encoded proteins, compromising several cellular functions and biological processes. There is currently no cure available for the progressive neurodegenerative disorders caused by the ensuing cytotoxic alterations. Although each disease is considered rare, polyQ diseases constitute the largest group of monogenic neurodegenerative disorders. Information about these disorders is scattered among several books, articles and general databases, hindering exploration by students and researchers, but also by patients and their families. Therefore, we aimed to develop a free online database to fill this gap, by centralizing relevant available information. The PolyQ Database is a platform that focuses on all nine polyQ diseases and offers information about topics that are pertinent for scientists, clinicians and the general public, including epidemiology, the characteristics of the causative genes and the codified proteins, the pathophysiology of the diseases and the main clinical manifestations. The database is available at https://polyq.pt/, and it is the first of its kind, focusing exclusively on this group of rare diseases. The database was conceived to be continuously updated and allow incorporation and dissemination of the latest information on polyQ diseases.

A novel INPP4A mutation with pontocerebellar hypoplasia, myoclonic epilepsy, microcephaly, and severe developmental delay.

BACKGROUND: The inositol polyphosphate 4-phosphatase intracellular signaling pathway is susceptible to genetic or epigenetic alterations that may result in major neurological illnesses with clinically significant pons and cerebellum involvement. CASE REPORTS: A seven-year-old girl with pontocerebellar hypoplasia, resistant myoclonic epilepsy with axial hypotonia, microcephaly, atypical facial appearance, nystagmus, ophthalmoplegia, hyperactive tendon reflexes, spasticity, clonus, extensor plantar response, contractures in wrists and ankles and growth retardation, whole-exome sequencing was performed and a homozygous "NM_001134225.2:c.646C > T, p.(Arg216Ter)" variant was found in the INPP4A gene. CONCLUSION: INPP4A mutations should be kept in mind in cases with severely delayed psychomotor development, progressive microcephaly, resistant myoclonic epilepsy, isolated cerebellum, and pons involvement.

TSEN54 Gene-Related Pontocerebellar-Hypoplasia and Role of Prenatal MR Imaging: Besides the Common Posterior Fossa Cystic Malformations.

Pontocerebellar-hypoplasia (PCH) related to TSEN54-gene mutation, a rare autosomal recessive disorder, can be associated with three different phenotypes: PCH2A, PCH4 and PCH5. Prenatal imaging features are very scant, in particular for PCH4 and PCH5. The aim of this letter is to illustrate key role of prenatal MR imaging in better evaluation of the cerebellar vermis-hemispheres and pons, which may lead to the differential diagnosis between three PCH TSEN54-related phenotypes already at mid-gestation based on the pattern of the degree of involvement of the vermis and the cerebellar cortex respectively.

Common Variants Near ZIC1 and ZIC4 in Autopsy-Confirmed Multiple System Atrophy.

BACKGROUND: Multiple System Atrophy is a rare neurodegenerative disease with alpha-synuclein aggregation in glial cytoplasmic inclusions and either predominant olivopontocerebellar atrophy or striatonigral degeneration, leading to dysautonomia, parkinsonism, and cerebellar ataxia. One prior genome-wide association study in mainly clinically diagnosed patients with Multiple System Atrophy failed to identify genetic variants predisposing for the disease. OBJECTIVE: Since the clinical diagnosis of Multiple System Atrophy yields a high rate of misdiagnosis when compared to the neuropathological gold standard, we studied only autopsy-confirmed cases. METHODS: We studied common genetic variations in Multiple System Atrophy cases (N = 731) and controls (N = 2898). RESULTS: The most strongly disease-associated markers were rs16859966 on chromosome 3, rs7013955 on chromosome 8, and rs116607983 on chromosome 4 with P-values below 5 × 10-6 , all of which were supported by at least one additional genotyped and several imputed single nucleotide polymorphisms. The genes closest to the chromosome 3 locus are ZIC1 and ZIC4 encoding the zinc finger proteins of cerebellum 1 and 4 (ZIC1 and ZIC4). INTERPRETATION: Since mutations of ZIC1 and ZIC4 and paraneoplastic autoantibodies directed against ZIC4 are associated with severe cerebellar dysfunction, we conducted immunohistochemical analyses in brain tissue of the frontal cortex and the cerebellum from 24 Multiple System Atrophy patients. Strong immunohistochemical expression of ZIC4 was detected in a subset of neurons of the dentate nucleus in all healthy controls and in patients with striatonigral degeneration, whereas ZIC4-immunoreactive neurons were significantly reduced inpatients with olivopontocerebellar atrophy. These findings point to a potential ZIC4-mediated vulnerability of neurons in Multiple System Atrophy. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

[Analysis of genetic variant in a fetus featuring pontocerebellar hypoplasia type 6].

OBJECTIVE: To explore the genetic basis for a fetus with cerebellar dysplasia and widened lateral ventricles. METHODS: The couple have elected induced abortion after careful counseling. Skin tissue sample from the abortus and peripheral venous blood samples from both parents were collected for the extraction of genomic DNA, which was then subjected to whole exome sequencing. Candidate variant was verified by Sanger sequencing. RESULTS: Prenatal ultrasonography showed increased nuchal translucency (0.4 cm) and widened lateral ventricles. Magnetic resonance imaging revealed infratentorial brain dysplasia. By DNA sequencing, the fetus was found to carry compound heterozygous variants c.1A>G and c.1564G>A of the RARS2 gene, which were inherited from its father and mother, respectively. Among these, c.1A>G was known to be pathogenic, but the pathogenicity of c.1564G>A was unreported previously. Based on the American College of Medical Genetics and Genomics guidelines, the c.1564G>A variant of RARS2 gene was predicted to be likely pathogenic(PM2+PM3+PP3+PP4). CONCLUSION: The compound heterozygous variants c.1A>G and c.1564G>A of RARS2 gene contributed to the fetus suffering from pontocerebellar hypoplasia type 6, which expanded variant spectrum of RARS2 gene.

Expanded PCH1D phenotype linked to EXOSC9 mutation.

Pontocerebellar Hypoplasia type 1 is a rare heterogeneous neurodegenerative disorder with multiple subtypes linked to dysfunction of the exosome complex. Patients with mutations in exosome subunits exhibit a generally lethal phenotype characterized by cerebellar and pontine hypoplasia in association with spinal motor neuropathy and multiple systemic and neurologic features. Recently, two variants in the novel PCH1 associated protein EXOSC9 p.(Leu14Pro) and p.(Arg161*) have been identified in 4 unrelated patients exhibiting a severe phenotype involving cerebellar hypoplasia, axonal motor neuropathy, hypotonia, feeding difficulties, and respiratory insufficiency (PCH1D). We report clinical and molecular characterization of 2 unrelated patients exhibiting a relatively milder phenotype involving hypotonia, brachycephaly, cerebellar atrophy, psychomotor delay, as well as lactic acidosis and aberrant CNS myelination, resulting from the recurring homozygous missense mutation NM_001034194.1: c.41T>C; p.(Leu14Pro) in the EXOSC9 gene. We review the clinical picture of the EXOSC9-related PCH disorder.

New Radiologic Findings of Hypertrophic Olivary Degeneration in 2 Patients with Brainstem Lymphoma.

BACKGROUND: Hypertrophic olivary degeneration (HOD) is a rare neurological condition of trans-synaptic degeneration caused by disruption of the dentatorubro-olivary pathway. We present new radiologic findings of HOD in 2 cases of brainstem lymphoma. CASE DESCRIPTION: A 35-year-old woman (Case 1) and a 69-year-old man (Case 2) presented with remarkably similar clinical courses. The primary lesion was located at the dorsal pons extending to the midbrain. Pathologic diagnosis of diffuse large B-cell lymphoma was obtained after surgical resection. Complete remission of the primary lesion was achieved by treatment with 3 courses of high-dose methotrexate and radiotherapy. Arterial spin-labeling and T2-weighted imagings showed high signal intensity in the inferior olive (IO) at some time after the operation. Slight contrast enhancement in the IO was also found in Case 1. These radiologic findings nearly misled us into a diagnosis of recurrence of lymphoma. Signal intensity in the IO on arterial spin-labeling imaging changed with time. Normalized regional cerebral blood flow (rCBF) in the IO was defined as a percentage of rCBF to the global cerebral blood flow calculated using automated software. Chronologic change in normalized rCBF in the IO revealed a large peak in Case 1, but only a mild increase in Case 2. Neurological findings demonstrated severe oculopalatal tremor in Case 1 and mild palatal tremor in Case 2. CONCLUSIONS: Hyperperfusion and contrast enhancement in the IO were found in 2 patients with HOD. These findings may be confused with recurrence of malignant tumor.

Sarcomeric disorganization and nemaline bodies in muscle biopsies of patients with EXOSC3-related type 1 pontocerebellar hypoplasia.

INTRODUCTION: Mutations in the EXOSC3 gene are responsible for type 1 pontocerebellar hypoplasia, an autosomal recessive congenital disorder characterized by cerebellar atrophy, developmental delay, and anterior horn motor neuron degeneration. Muscle biopsies of these patients often show characteristics resembling classic spinal muscle atrophy, but to date, no distinct features have been identified. METHODS: Clinical data and muscle biopsy findings of 3 unrelated patients with EXOSC3 mutations are described. RESULTS: All patients presented as a severe congenital cognitive and neuromuscular phenotype with short survival, harboring the same point mutation (c.92G>C; p.Gly31Ala). Muscle biopsies consistently showed variable degrees of sarcomeric disorganization with myofibrillar remnants, Z-line thickening, and small nemaline bodies. CONCLUSIONS: In this uniform genetic cohort of patients with EXOSC3 mutations, sarcomeric disruption and rod structures were prominent features of muscle biopsies. In the context of neonatal hypotonia, ultrastructural studies might provide early clues for the diagnosis of EXOSC3-related pontocerebellar hypoplasia. Muscle Nerve 59:137-141, 2019.

Unilateral Symptomatic Hypertrophic Olivary Degeneration Secondary to Midline Brainstem Cavernous Angioma: A Case Report and Review of the Literature.

BACKGROUND: Hypertrophic olivary degeneration (HOD) is a rare phenomenon in the dento-rubro-olivary pathway caused by lesion or disruption of the fibers of the Guillain-Mollaret triangle. Hemorrhage of pontine and midbrain cavernous angiomas can rarely lead to HOD portending neurologic deterioration and possible concomitant life-threatening complications; for this reason, it may define a poignant consideration in planning intervention. CASE DESCRIPTION: The patient was a 57-year-old woman with known midbrain-pontine cavernous angioma. For several years, the lesion had been stable, as shown by imaging follow-up, until 10 months before the patient presented with falls, dysarthria, and headache. Imaging showed some decrease in size as well as blood product around the cavernous angioma, suggesting interim period hemorrhage and interval development of HOD. CONCLUSIONS: The literature regarding imaging recommendations for stable cavernous angioma in the midbrain-pontine junction is reviewed. The implication of HOD for patient outcome is discussed and a comment is made on how the development of HOD may affect management of the cavernous angioma.

A New Patient With Intermediate Severe Salla Disease With Hypomyelination: A Literature Review for Salla Disease.

BACKGROUND: Likely pathogenic variants in SLC17A5 results in allelic disorders of free sialic acid metabolism including (1) infantile free sialic acid storage disease with severe global developmental delay, coarse facial features, hepatosplenomegaly, and cardiomegaly; (2) intermediate severe Salla disease with moderate to severe global developmental delay, hypotonia, and hypomyelination with or without coarse facial features, and (3) Salla disease with normal appearance, mild cognitive dysfunction, and spasticity. PATIENT DESCRIPTION: This five-year-old girl presented with infantile-onset severe global developmental delay, truncal hypotonia, and generalized dystonia following normal development during her first six months of life. Brain magnetic resonance imaging showed marked hypomyelination and a thin corpus callosum at age 19 months, both unchanged on follow-up at age 28 months. Urine free sialic acid was moderately elevated. Cerebrospinal fluid free sialic acid was marginally elevated. Sequencing of SLC17A5 revealed compound heterozygous likely pathogenic variants, namely, a known missense (c.291G>A) variant and a novel truncating (c.819+1G>A) variant, confirming the diagnosis of Salla disease at age 3.5 years. CONCLUSION: We report a new patient with intermediate severe Salla disease. Normal or marginally elevated urine or cerebrospinal fluid free sialic acid levels cannot exclude Salla disease. In patients with progressive global developmental delay and hypomyelination on brain magnetic resonance imaging, Salla disease should be included into the differential diagnosis.

Progression of subcortical atrophy and iron deposition in multiple system atrophy: a comparison between clinical subtypes.

Magnetic resonance imaging (MRI) can be useful not only for the diagnosis of multiple system atrophy (MSA) itself, but also to distinguish between different clinical subtypes. This study aimed to investigate whether there are differences in the progression of subcortical atrophy and iron deposition between two variants of MSA. Two serial MRIs at baseline and follow-up were analyzed in eight patients with the parkinsonian variant MSA (MSA-P), nine patients with cerebellar variant MSA (MSA-C), and fifteen patients with Parkinson's disease (PD). The R2* values and volumes were calculated for the selected subcortical structures (caudate nucleus, putamen, globus pallidus, and thalamus) using an automated region-based analysis. In both volume and R2*, a higher rate of progression was identified in MSA-P patients. Volumetric analysis showed significantly more rapid progression of putamen and caudate nucleus in MSA-P than in MSA-C. With regard to R2* changes, a significant increase at follow-up and a higher rate of progression were identified in the putamen of MSA-P group compared to MSA-C and PD groups. This longitudinal study revealed different progression rates of MRI markers between MSA-P and MSA-C. Iron-related degeneration in the putamen may be more specific for MSA-P.

Narcolepsy is a common phenotype in HSAN IE and ADCA-DN.

We report on the extensive phenotypic characterization of five Italian patients from four unrelated families carrying dominant heterozygous DNMT1 mutations linked to two distinct autosomal dominant diseases: hereditary sensory and autonomic neuropathy with dementia and hearing loss type IE (HSAN IE) and autosomal dominant cerebellar ataxia, deafness and narcolepsy (ADCA-DN). Patients underwent genetic analysis of DNMT1 gene, neurophysiological tests investigating sleep, auditory functions and peripheral nervous system, ophthalmological studies including optical coherence tomography, lymphoscintigraphy, brain magnetic resonance and nuclear imaging, cerebrospinal fluid hypocretin-1, total tau, phosphorylated tau, amyloid-ß1-42 and 14-3-3 proteins measurement, skin, muscular and sural nerve biopsies. Exome and direct sequencing studies disclosed two different point mutations affecting exon 21 of DNMT1 gene in patients with ADCA-DN, a novel heterozygous point mutation in exon 20 in two affected HSAN IE siblings, and a trinucleotide deletion in exon 20 in the latter patient with HSAN IE. Phenotypic characterization pinpoints that ADCA-DN and HSAN IE represent two discrete clinical entities belonging to the same disease spectrum, with variable degree of overlap. Remarkably, narcolepsy with or without cataplexy with low/intermediate or normal cerebrospinal fluid hypocretin-1 is present in both diseases. The human leukocyte antigen DQB1*06:02 was absent in all patients. Other common symptoms and features observed in our cases, involving the central and peripheral nervous system, include deafness, optic neuropathy-previously not reported in HSAN IE-large and small fibres polyneuropathy and lower limbs oedema. Overall, the two syndromes share more characteristics than previously recognized and narcolepsy is common to both. HSAN IE and ADCA-DN are two extreme phenotypic manifestations of a DNMT1 methylopathy.

EXOSC3 mutations in pontocerebellar hypoplasia type 1: novel mutations and genotype-phenotype correlations.

BACKGROUND: Pontocerebellar hypoplasia (PCH) represents a group of neurodegenerative disorders with prenatal onset. Eight subtypes have been described thus far (PCH1-8) based on clinical and genetic features. Common characteristics include hypoplasia and atrophy of the cerebellum, variable pontine atrophy, and severe mental and motor impairments. PCH1 is distinctly characterized by the combination with degeneration of spinal motor neurons. Recently, mutations in the exosome component 3 gene (EXOSC3) have been identified in approximately half of the patients with PCH subtype 1. METHODS: We selected a cohort of 99 PCH patients (90 families) tested negative for mutations in the TSEN genes, RARS2, VRK1 and CASK. Patients in this cohort were referred with a tentative diagnose PCH type 1, 2, 4, 7 or unclassified PCH. Genetic analysis of the EXOSC3 gene was performed using Sanger sequencing. Clinical data, MR images and autopsy reports of patients positive for EXOSC3 mutations were analyzed. RESULTS: EXOSC3 mutations were found in twelve families with PCH subtype 1, and were not found in patients with other PCH subtypes. Identified mutations included a large deletion, nonsense and missense mutations. Examination of clinical data reveals a prolonged disease course in patients with a homozygous p.D132A mutation. MRI shows variable pontine hypoplasia in EXOSC3 mediated PCH, where the pons is largely preserved in patients with a homozygous p.D132A mutation, but attenuated in patients with other mutations. Additionally, bilateral cerebellar cysts were found in patients compound heterozygous for a p.D132A mutation and a nonsense allele. CONCLUSIONS: EXOSC3 mediated PCH shows clear genotype-phenotype correlations. A homozygous p.D132A mutation leads to PCH with possible survival into early puberty, and preservation of the pons. Compound heterozygosity for a p.D132A mutation and a nonsense or p.Y109N allele, a homozygous p.G31A mutation or a p.G135E mutation causes a more rapidly progressive course leading to death in infancy and attenuation of the ventral pons.Our findings imply a clear correlation between genetic mutation and clinical outcome in EXOSC3 mediated PCH, including variable involvement of the pons.

AMPD2 regulates GTP synthesis and is mutated in a potentially treatable neurodegenerative brainstem disorder.

Purine biosynthesis and metabolism, conserved in all living organisms, is essential for cellular energy homeostasis and nucleic acid synthesis. The de novo synthesis of purine precursors is under tight negative feedback regulation mediated by adenosine and guanine nucleotides. We describe a distinct early-onset neurodegenerative condition resulting from mutations in the adenosine monophosphate deaminase 2 gene (AMPD2). Patients have characteristic brain imaging features of pontocerebellar hypoplasia (PCH) due to loss of brainstem and cerebellar parenchyma. We found that AMPD2 plays an evolutionary conserved role in the maintenance of cellular guanine nucleotide pools by regulating the feedback inhibition of adenosine derivatives on de novo purine synthesis. AMPD2 deficiency results in defective GTP-dependent initiation of protein translation, which can be rescued by administration of purine precursors. These data suggest AMPD2-related PCH as a potentially treatable early-onset neurodegenerative disease.

The very low density lipoprotein receptor-associated pontocerebellar hypoplasia and dysmorphic features in three Turkish patients.

Pontocerebellar hypoplasia consists of a rare heterogeneous group of congenital neurodevelopmental disorders characterized by hypoplasia and atrophy of the cerebellar cortex, dentate and pontine nuclei, and inferior olives. The very low density lipoprotein receptor protein is an integral part of the reelin signaling pathway, which guides neuroblast migration in the cerebral cortex and cerebellum. Mutations in this receptor cause nonprogressive cerebellar ataxia, mental retardation, and cerebellar hypoplasia. In this report, we present 3 patients from 2 different families displaying very low density lipoprotein receptor-associated pontocerebellar hypoplasia, cortical dysplasia, mental retardation, and bipedal gait. One of the siblings has also displayed dysmorphic features, as we previously reported before the identification of the genetic defect in this family.

Pontocerebellar hypoplasia type 6 caused by mutations in RARS2: definition of the clinical spectrum and molecular findings in five patients.

Recessive mutations in the mitochondrial arginyl-transfer RNA synthetase (RARS2) gene have been associated with early onset encephalopathy with signs of oxidative phosphorylation defects classified as pontocerebellar hypoplasia 6. We describe clinical, neuroimaging and molecular features on five patients from three unrelated families who displayed mutations in RARS2. All patients rapidly developed a neonatal or early-infantile epileptic encephalopathy with intractable seizures. The long-term follow-up revealed a virtual absence of psychomotor development, progressive microcephaly, and feeding difficulties. Mitochondrial respiratory chain enzymes in muscle and fibroblasts were normal in two. Blood and CSF lactate was abnormally elevated in all five patients at early stages while appearing only occasionally abnormal with the progression of the disease. Cerebellar vermis hypoplasia with normal aspect of the cerebral and cerebellar hemispheres appeared within the first months of life at brain MRI. In three patients follow-up neuroimaging revealed a progressive pontocerebellar and cerebral cortical atrophy. Molecular investigations of RARS2 disclosed the c.25A>G/p.I9V and the c.1586+3A>T in family A, the c.734G>A/p.R245Q and the c.1406G>A/p.R469H in family B, and the c.721T>A/p.W241R and c.35A>G/p.Q12R in family C. Functional complementation studies in Saccharomyces cerevisiae showed that mutation MSR1-R531H (equivalent to human p.R469H) abolished respiration whereas the MSR1-R306Q strain (corresponding to p.R245Q) displayed a reduced growth on non-fermentable YPG medium. Although mutations functionally disrupted yeast we found a relatively well preserved arginine aminoacylation of mitochondrial tRNA. Clinical and neuroimaging findings are important clues to raise suspicion and to reach diagnostic accuracy for RARS2 mutations considering that biochemical abnormalities may be absent in muscle biopsy.

Generation of induced pluripotent stem cells from skin fibroblasts of a patient with olivopontocerebellar atrophy.

Generation of induced pluripotent stem (iPS) cells from somatic cells of patients represents a powerful tool for disease modeling, and they may have a wide range of applications in cell therapies. Olivopontocerebellar atrophy (OPCA) is a rare and debilitating neurologic disease of insidious onset, characterized by atrophy of the cerebellum pons and inferior olivary nuclei with concomitant ambulation deficits and dyscoordination. Here, we report the generation of iPS cells from skin fibroblasts of a 56-year-old female patient with familial OPCA. OPCA is classified in the autosomal dominant ataxia that is also named spinocerebellar ataxia (SCA) 7. The disease allele of SCA7 gene of the patient contains 45 CAG trinucleotide repeats, the number of which is larger than the normal repeat number (4 to 36 CAG repeats). The OPCA-iPS cells were generated via ectopic expression of four transcription factors: OCT4, SOX2, KLF4 and c-MYC. The OPCA-iPS cells expressed the pluripotency markers, and they can be differentiated into various somatic cell types in vitro and in vivo. Furthermore, the iPS cells also can be committed to differentiate into neural cells. Therefore, the OPCA-iPS cells offer an unprecedented cell model to investigate disease mechanisms, discover novel drugs, and develop new therapies for OPCA.

Identification of a novel in-frame de novo mutation in SPTAN1 in intellectual disability and pontocerebellar atrophy.

Heterozygous in-frame mutations (p.E2207del and p.R2308_M2309dup) in the α-II subunit of spectrin (SPTAN1) were recently identified in two patients with intellectual disability (ID), infantile spasms (IS), hypomyelination, and brain atrophy. These mutations affected the C-terminal domain of the protein, which contains the nucleation site of the α/ß spectrin heterodimer. By screening SPTAN1 in 95 patients with idiopathic ID, we found a de novo in-frame mutation (p.Q2202del) in the same C-terminal domain in a patient with mild generalized epilepsy and pontocerebellar atrophy, but without IS, hypomyelination, or other brain structural defects, allowing us to define the core phenotype associated with these C-terminal SPTAN1 mutations. We also found a de novo missense variant (p.R566P) of unclear clinical significance in a patient with non-syndromic ID. These two mutations induced different patterns of aggregation between spectrin subunits in transfected neuronal cell lines, providing a paradigm for the classification of candidate variants.