Novel molecular, structural and clinical findings in an Italian cohort of congenital cataract.

The current genetic diagnostic workup of congenital cataract (CC) is mainly based on NGS panels, whereas exome sequencing (ES) has occasionally been employed. In this multicentre study, we investigated by ES the detection yield, mutational spectrum and genotype-phenotype correlations in a CC cohort recruited between 2020 and mid-2022. The cohort consisted of 67 affected individuals from 51 unrelated families and included both non-syndromic (75%) and syndromic (25%) phenotypes, with extra-CC ocular/visual features present in both groups (48% and 76%, respectively). The functional effect of variants was predicted by 3D modelling and hydropathy properties changes. Variant clustering was used for the in-depth assessment of genotype-phenotype correlations. A diagnostic (pathogenic or likely pathogenic) variant was identified in 19 out of 51 probands/families (~37%). In a further 14 probands/families a candidate variant was identified: in 12 families a VUS was detected, of which 9 were considered plausibly pathogenic (i.e., 4 or 5 points according to ACMG criteria), while in 2 probands ES identified a single variant in an autosomal recessive gene associated with CC. Eighteen probands/families, manifesting primarily non-syndromic CC (15/18, 83%), remained unsolved. The identified variants (8 P, 12 LP, 10 VUS-PP, and 5 VUS), half of which were unreported in the literature, affected five functional categories of genes involved in transcription/splicing, lens formation/homeostasis (i.e., crystallin genes), membrane signalling, cell-cell interaction, and immune response. A phenotype-specific variant clustering was observed in four genes (KIF1A, MAF, PAX6, SPTAN1), whereas variable expressivity and potential phenotypic expansion in two (BCOR, NHS) and five genes (CWC27, KIF1A, IFIH1, PAX6, SPTAN1), respectively. Finally, ES allowed to detect variants in six genes not commonly included in commercial CC panels. These findings broaden the genotype-phenotype correlations in one of the largest CC cohorts tested by ES, providing novel insights into the underlying pathogenetic mechanisms and emphasising the power of ES as first-tier test.

Feasibility and Efficacy of a Virtual Reality Social Prediction Training in Children and Young Adults with Congenital Cerebellar Malformations.

This study tested the feasibility and efficacy of a Virtual Reality (VR) social prediction training (VR-Spirit) specifically designed for patients with congenital cerebellar malformation. The study is a randomised controlled trial in which 28 cerebellar patients aged 7-25 yo were randomly allocated to the VR-Spirit or to a control intervention in VR. The VR-Spirit required participants to compete with different avatars in scenarios that prompted them to form predictions about avatars' intentions. The control intervention consisted of games currently adopted for motor rehabilitation. Social prediction as well as secondary neuropsychological and behavioural outcomes were assessed at the beginning (T0), at the end (T2) and after 2 months (T3). The experimental group showed a significant increase, compared to the control participants, in social prediction assessed through a VR task. Moreover, at least at T3, the VR-Spirit enhanced the use of contextual predictions in a computer-based action prediction task. Importantly, these effects were generalized to secondary neuropsychological outcomes, specifically theory of mind and, only at T2, inhibition. No differences between the interventions were detected on emotional-behavioural problems. Lastly, both interventions showed high feasibility and acceptability. These findings confirm that it is possible to develop condition-specific rehabilitative training on the basis of neurocognitive functions impaired in case of congenital malformation. The VR-Spirit demonstrated to generalize its effects to theory of mind abilities, and it might be thus extended to other neurodevelopmental disorders that present social perception deficits and alterations of predictive processing.Trial registration: ISRCTN, ID: ISRCTN22332873. Retrospectively registered on 12 March 2018.

LZTFL1, a rare cause of Bardet-Biedl syndrome: A new patient with severe short stature and moderate intellectual disability, more than casual associations?

Bardet-Biedl syndrome (BBS) is an inherited ciliopathy affecting multiple organs and systems with wide clinical and genetic heterogeneity. To date, biallelic variants of the LZTFL1 gene have been reported only in six patients with BBS. We identified a homozygous LZTFL1 nonsense variant in a boy presenting with classical BBS features. In addition, he showed a more pronounced cognitive impairment than previously reported subjects and severe short stature, matching the phenotype displayed by some other patients with LZTFL1 variants and lztfl1 knock-out mice. This case report contributes to a better understanding of the clinical spectrum associated with LZTFL1 pathogenic variants, and highlights possible genotype-phenotype correlations.

Functional Study of SNCA p.V15A Variant: Further Linking α-Synuclein and Glucocerebrosidase.

BACKGROUND: SNCA p.V15A was reported in five families. In vitro models showed increased aggregation and seeding activity, mitochondrial damage, and apoptosis. Mutant flies had reduced flying ability and survival. OBJECTIVES: To clinically and functionally evaluate SNCA p.V15A in a large Italian family with Parkinson's disease (PD). METHODS: Genetic diagnosis was reached through next-generation sequencing. Pathogenicity was assessed by molecular dynamics simulation and biochemical studies on peripheral blood mononuclear cells (PBMCs). RESULTS: Five siblings carried SNCA p.V15A; three developed bradykinetic-rigid PD in their 50s with rapid motor progression and variable cognitive impairment. A fourth sibling had isolated mood disturbance, whereas the fifth was still unaffected at age 47. The mutant protein showed decreased stability and an unstable folded structure. Proband's PBMCs showed elevated total and phosphorylated α-synuclein (α-syn) levels and significantly reduced glucocerebrosidase activity. CONCLUSION: This study demonstrates accumulation of α-synV15A in PBMCs and strengthens the link between α-syn pathophysiology and glucocerebrosidase dysfunction. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Joubert syndrome-derived induced pluripotent stem cells show altered neuronal differentiation in vitro.

Joubert syndrome (JS) is a recessively inherited congenital ataxia characterized by hypotonia, psychomotor delay, abnormal ocular movements, intellectual disability, and a peculiar cerebellar and brainstem malformation, the "molar tooth sign." Over 40 causative genes have been reported, all encoding for proteins implicated in the structure or functioning of the primary cilium, a subcellular organelle widely present in embryonic and adult tissues. In this paper, we developed an in vitro neuronal differentiation model using patient-derived induced pluripotent stem cells (iPSCs), to evaluate possible neurodevelopmental defects in JS. To this end, iPSCs from four JS patients harboring mutations in distinct JS genes (AHI1, CPLANE1, TMEM67, and CC2D2A) were differentiated alongside healthy control cells to obtain mid-hindbrain precursors and cerebellar granule cells. Differentiation was monitored over 31 days through the detection of lineage-specific marker expression by qRT-PCR, immunofluorescence, and transcriptomics analysis. All JS patient-derived iPSCs, regardless of the mutant gene, showed a similar impairment to differentiate into mid-hindbrain and cerebellar granule cells when compared to healthy controls. In addition, analysis of primary cilium count and morphology showed notable ciliary defects in all differentiating JS patient-derived iPSCs compared to controls. These results confirm that patient-derived iPSCs are an accessible and relevant in vitro model to analyze cellular phenotypes connected to the presence of JS gene mutations in a neuronal context.

Heterozygous APTX mutation associated with atypical multiple system atrophy-like phenotype: A case report.

We describe here a 73-year-old patient presenting with atypical MSA-P-like phenotype carrying a monoallelic p. W279X mutation in the APTX gene, which causes ataxia with oculomotor apraxia type 1 (AOA1) when in homozygous state. We hypothesize that rare monoallelic APTX variants could modulate MSA risk and phenotype.

Understanding monogenic Parkinson's disease at a global scale.

Until recently, about three-quarters of all monogenic Parkinson's disease (PD) studies were performed in European/White ancestry, thereby severely limiting our insights into genotype-phenotype relationships at global scale. The first systematic approach to embrace monogenic PD worldwide, The Michael J. Fox Foundation Global Monogenic PD (MJFF GMPD) Project, contacted authors of publications reporting individuals carrying pathogenic variants in known PD-causing genes. In contrast, the Global Parkinson's Genetics Program's (GP2) Monogenic Network took a different approach by targeting PD centers not yet represented in the medical literature. Here, we describe combining both efforts in a "merger project" resulting in a global monogenic PD cohort with build-up of a sustainable infrastructure to identify the multi-ancestry spectrum of monogenic PD and enable studies of factors modifying penetrance and expression of monogenic PD. This effort demonstrates the value of future research based on team science approaches to generate comprehensive and globally relevant results.

Paroxysmal Dystonic Posturing Mimicking Nocturnal Leg Cramps as a Presenting Sign in an Infant with DCC Mutation, Callosal Agenesis and Mirror Movements.

Background/Objectives: Pathogenic variants in the deleted in colorectal cancer gene (DCC), encoding the Netrin-1 receptor, may lead to mirror movements (MMs) associated with agenesis/dysgenesis of the corpus callosum (ACC) and cognitive and/or neuropsychiatric issues. The clinical phenotype is related to the biological function of DCC in the corpus callosum and corticospinal tract development as Netrin-1 is implicated in the guidance of developing axons toward the midline. We report on a child with a novel inherited, monoallelic, pathogenic variant in the DCC gene. Methods: Standardized measures and clinical scales were used to assess psychomotor development, communication and social skills, emotional and behavioural difficulties. MMs were measured via the Woods and Teuber classification. Exome sequencing was performed on affected and healthy family members. Results: The patient's clinical presentation during infancy consisted of paroxysmal dystonic posturing when asleep, mimicking nocturnal leg cramps. A brain magnetic resonance imaging (MRI) showed complete ACC. He developed typical upper limb MMs during childhood and a progressively evolving neuro-phenotype with global development delay and behavioural problems. We found an intrafamilial clinical variability associated with DCC mutations: the proband's father and uncle shared the same DCC variant, with a milder clinical phenotype. The atypical early clinical presentation of the present patient expands the clinical spectrum associated with DCC variants, especially those in the paediatric age. Conclusions: This study underlines the importance of in-depth genetic investigations in young children with ACC and highlights the need for further detailed analyses of early motor symptoms in infants with DCC mutations.

Cerebellar Heterotopia: Broadening the Neuroradiological Spectrum of KBG Syndrome.

KBG syndrome is a rare genetic disorder caused by heterozygous pathogenic variants in ANKRD11. Affected individuals have developmental delay, short stature, characteristic facial features, and other dysmorphic findings. To date, a spectrum of unspecific neuroradiological defects has been reported in KBG patients, such as cortical defects, white matter abnormalities, corpus callosum, and cerebellar vermis hypoplasia.Deep clinical and neuroradiological phenotyping and genotype of a patient presenting with mild cognitive and behavioral problems were obtained after written informed consent.We herein describe the first KBG patient presenting with cerebellar heterotopia, a heterogeneous malformation characterized by the presence of clusters of neurons within the white matter of cerebellar hemispheres.This novel association broadens the neuroradiological spectrum of KBG syndrome, and further prompts to investigate the potential functions of ANKRD11 in cerebellar development.

Distribution of the C9orf72 hexanucleotide repeat expansion in healthy subjects: a multicenter study promoted by the Italian IRCCS network of neuroscience and neurorehabilitation.

Introduction: High repeat expansion (HRE) alleles in C9orf72 have been linked to both amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD); ranges for intermediate allelic expansions have not been defined yet, and clinical interpretation of molecular data lacks a defined genotype-phenotype association. In this study, we provide results from a large multicenter epidemiological study reporting the distribution of C9orf72 repeats in healthy elderly from the Italian population. Methods: A total of 967 samples were collected from neurologically evaluated healthy individuals over 70 years of age in the 13 institutes participating in the RIN (IRCCS Network of Neuroscience and Neurorehabilitation) based in Italy. All samples were genotyped using the AmplideXPCR/CE C9orf72 Kit (Asuragen, Inc.), using standardized protocols that have been validated through blind proficiency testing. Results: All samples carried hexanucleotide G4C2 expansion alleles in the normal range. All samples were characterized by alleles with less than 25 repeats. In particular, 93.7% of samples showed a number of repeats ≤10, 99.9% ≤20 repeats, and 100% ≤25 repeats. Conclusion: This study describes the distribution of hexanucleotide G4C2 expansion alleles in an Italian healthy population, providing a definition of alleles associated with the neurological healthy phenotype. Moreover, this study provides an effective model of federation between institutes, highlighting the importance of sharing genomic data and standardizing analysis techniques, promoting translational research. Data derived from the study may improve genetic counseling and future studies on ALS/FTD.

Parkin mRNA Expression Levels in Peripheral Blood Mononuclear Cells in Parkin-Related Parkinson's Disease.

INTRODUCTION: Pathogenic variants in parkin (PRKN gene) are the second most prevalent known monogenic cause of Parkinson's disease (PD). How monoallelic or biallelic pathogenic variants in the PRKN gene may affect its transcription in patient-derived biological material has not been systematically studied. METHODS: PRKN mRNA expression levels were measured with real-time polymerase chain reaction (RT-PCR) in peripheral blood mononuclear cells (PBMCs). PBMCs were derived from PRKN-mutated PD patients (PRKN-PD) (n = 12), sporadic PD (sPD) (n = 21) and healthy controls (n = 21). Six of the PRKN-PD patients were heterozygous, four were compound heterozygous, and two were homozygous for PRKN variants. RESULTS: A statistically significant decrease in PRKN expression levels was present, compared to healthy controls and sPD, in heterozygous (P = 0.019 and 0.031 respectively) and biallelic (P < 0.001 for both) PRKN-PD. PRKN expression levels in biallelic PD patients were uniformly very low and were reduced, albeit not significantly, compared to heterozygotes. Based on receiver operating characteristic analysis, low PRKN expression levels were a sensitive and extremely specific indicator for the presence of PRKN pathogenic variants. CONCLUSIONS: Assessment of PRKN mRNA levels in PBMCs may be a useful way to screen for biallelic pathogenic variants in the PRKN gene. Suspicion for certain variants in a heterozygous state may also be raised based on low PRKN mRNA levels. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Cerebellar heterotopia in an 11-year-old child with KDM6B-related neurodevelopmental disorder: A case report and review of the literature.

Heterozygous pathogenic variants in KDM6B have recently been associated to a rare neurodevelopmental disorder referred to as "Neurodevelopmental disorder with coarse facies and mild distal skeletal abnormalities" and characterized by non-pathognomonic facial and body dysmorphisms, a wide range of neurodevelopmental and behavioral disorders and nonspecific neuroradiological findings. KDM6B encodes a histone demethylase, expressed in different tissues during development, which regulates gene expression through the modulation of chromatin accessibility by RNA polymerase. We herein describe a 11-year-old male patient carrying a novel de novo pathogenic variant in KDM6B exhibiting facial dysmorphisms, dysgraphia, behavioral traits relatable to oppositional defiant, autism spectrum, and attention deficit hyperactivity disorders, a single seizure episode, and a neuroimaging finding of a single cerebellar heterotopic nodule, never described to date in this genetic condition. These findings expand the phenotypic spectrum of this syndrome, highlighting the potential role for KDM6B in cerebellar development and providing valuable insights for genetic counseling.

Blood D-serine levels correlate with aging and dopaminergic treatment in Parkinson's disease.

We recently described increased D- and L-serine concentrations in the striatum of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated monkeys, the post-mortem caudate-putamen of human Parkinson's disease (PD) brains and the cerebrospinal fluid (CSF) of de novo living PD patients. However, data regarding blood D- and L-serine levels in PD are scarce. Here, we investigated whether the serum profile of D- and L-serine, as well as the other glutamate N-methyl-D-aspartate ionotropic receptor (NMDAR)-related amino acids, (i) differs between PD patients and healthy controls (HC) and (ii) correlates with clinical-demographic features and levodopa equivalent daily dose (LEDD) in PD. Eighty-three consecutive PD patients and forty-one HC were enrolled. PD cohort underwent an extensive clinical characterization. Serum levels of D- and L-serine, L-glutamate, L-glutamine, L-aspartate, L-asparagine and glycine were determined using High Performance Liquid Chromatography. In age- and sex-adjusted analyses, no differences emerged in the serum levels of D-serine, L-serine and other NMDAR-related amino acids between PD and HC. However, we found that D-serine and D-/Total serine ratio positively correlated with age in PD but not in HC, and also with PD age at onset. Moreover, we found that higher LEDD correlated with lower levels of D-serine and the other excitatory amino acids. Following these results, the addition of LEDD as covariate in the analyses disclosed a selective significant increase of D-serine in PD compared to HC (Δ ≈ 38%). Overall, these findings suggest that serum D-serine and D-/Total serine may represent a valuable biochemical signature of PD.

Visual function in children with Joubert syndrome.

AIM: To describe visual function in children with Joubert syndrome and to investigate its possible association with diagnostic and developmental aspects. METHOD: This retrospective cross-sectional work included 59 patients (33 male; mean age 9 years 2 months, standard deviation 6 years 3 months, range 4 months to 23 years) diagnosed with Joubert syndrome from January 2002 to December 2020. Data about clinical (neurological, neuro-ophthalmological, developmental/cognitive) and diagnostic (e.g. genetic testing, neuroimaging, systemic involvement) evaluations were collected in a data set during a review of medical records. Clinical and diagnostic variables were described in terms of raw counts and percentages. A χ2 test was conducted to investigate their association with neuropsychological skills. RESULTS: Ocular motor apraxia was highly represented in our cohort (75%), with a high prevalence of refractive defects and retinal abnormalities. Developmental delay/intellectual disability was frequent (in 69.5% of the sample), associated with retinal dystrophy (p = 0.047) and reduced visual acuity both for near (p = 0.014) and for far distances (p = 0.017). INTERPRETATION: On the basis of the relevance of oculomotor and perceptual alterations and their impact on overall and cognitive impairment, we encourage early and multidisciplinary assessment and follow-up of visual function in children with Joubert syndrome. This would help in planning a personalized rehabilitation to sustain functional vision. Further studies will be important to explore the link between biological aspects and global functioning in children with Joubert syndrome. WHAT THIS PAPER ADDS: Perceptual deficits and oculomotor impairments frequently coexist in Joubert syndrome. Retinal dysfunction may be present despite the absence of funduscopic abnormalities. Both perceptual and oculomotor impairments negatively affect cognitive development in Joubert syndrome.

Are patients with GBA-Parkinson disease good candidates for deep brain stimulation? A longitudinal multicentric study on a large Italian cohort.

BACKGROUND: GBA variants increase the risk of developing Parkinson disease (PD) and influence its outcome. Deep brain stimulation (DBS) is a recognised therapeutic option for advanced PD. Data on DBS long-term outcome in GBA carriers are scarce. OBJECTIVE: To elucidate the impact of GBA variants on long-term DBS outcome in a large Italian cohort. METHODS: We retrospectively recruited a multicentric Italian DBS-PD cohort and assessed: (1) GBA prevalence; (2) pre-DBS clinical features; and (3) outcomes of motor, cognitive and other non-motor features up to 5 years post-DBS. RESULTS: We included 365 patients with PD, of whom 73 (20%) carried GBA variants. 5-year follow-up data were available for 173 PD, including 32 mutated subjects. GBA-PD had an earlier onset and were younger at DBS than non-GBA-PD. They also had shorter disease duration, higher occurrence of dyskinesias and orthostatic hypotension symptoms.At post-DBS, both groups showed marked motor improvement, a significant reduction of fluctuations, dyskinesias and impulsive-compulsive disorders (ICD) and low occurrence of most complications. Only cognitive scores worsened significantly faster in GBA-PD after 3 years. Overt dementia was diagnosed in 11% non-GBA-PD and 25% GBA-PD at 5-year follow-up. CONCLUSIONS: Evaluation of long-term impact of GBA variants in a large Italian DBS-PD cohort supported the role of DBS surgery as a valid therapeutic strategy in GBA-PD, with long-term benefit on motor performance and ICD. Despite the selective worsening of cognitive scores since 3 years post-DBS, the majority of GBA-PD had not developed dementia at 5-year follow-up.

Impaired Mitochondrial Respiration in REM-Sleep Behavior Disorder: A Biomarker of Parkinson's Disease?

BACKGROUND: Idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD) is associated with prodromal Parkinson's disease (PD), but the mechanisms linking phenoconversion of iRBD to PD have not yet been clarified. Considering the association between mitochondrial dysfunction and sleep disturbances in PD, we explored mitochondrial activity in fibroblasts derived from iRBD patients to identify a biochemical profile that could mark the presence of impending neurodegeneration. METHODS: The study involved 28 participants, divided into three groups: patients diagnosed with iRBD, PD patients converted from iRBD (RBD-PD), and healthy controls. We performed a comprehensive assessment of mitochondrial function, including an examination of mitochondrial morphology, analysis of mitochondrial protein expression levels by western blot, and measurement of mitochondrial respiration using the Seahorse XFe24 analyzer. RESULTS: In basal conditions, mitochondrial respiration did not differ between iRBD and control fibroblasts, but when cells were challenged with a higher energy demand, iRBD fibroblasts exhibited a significant (P = 0.006) drop in maximal and spare respiration compared to controls. Interestingly, RBD-PD patients showed the same alterations with a further significant reduction in oxygen consumption linked to adenosine triphosphate production (P = 0.032). Moreover, RBD-PD patients exhibited a significant decrease in protein levels of complexes III (P = 0.02) and V (P = 0.002) compared to controls, along with fragmentation of the mitochondrial network. iRBD patients showed similar, but milder alterations. CONCLUSIONS: Altogether, these findings suggest that mitochondrial dysfunctions in individuals with iRBD might predispose to worsening of the bioenergetic profile observed in RBD-PD patients, highlighting these alterations as potential predictors of phenoconversion to PD. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Expanding the phenotype of Brunner syndrome from childhood to adulthood: Description of the second pediatric patient and his mother.

Brunner syndrome is a recessive X-linked disorder caused by pathogenic variants in the monoamine oxidase A gene (MAOA). It is characterized by distinctive aggressive behavior, mild intellectual disability, sleep disturbances, and typical biochemical alterations deriving from the impaired monoamine metabolism. We herein describe a 5-year-old boy with developmental delay, autistic features, and myoclonic epilepsy, and his mother, who had mild intellectual disability and recurrent episodes of palpitations, headache, abdominal pain, and abdominal bloating. Whole exome sequencing allowed detection of the maternally-inherited variant c.410A>G, (p.Glu137Gly) in the MAOA gene. The subsequent biochemical studies confirmed the MAOA deficiency both in the child and his mother. Given the serotonergic symptoms associated with high serotonin levels found in the mother, treatment with a serotonin reuptake inhibitor and dietary modifications were carried out, resulting in regression of the biochemical abnormalities and partial reduction of symptoms. Our report expands the phenotypic spectrum of Brunner disease, bringing new perspectives on the behavioral and neurodevelopmental phenotype from childhood to adulthood.