Using Cluster Analysis to Overcome the Limits of Traditional Phenotype-Genotype Correlations: The Example of RYR1-Related Myopathies.

Thanks to advances in gene sequencing, RYR1-related myopathy (RYR1-RM) is now known to manifest itself in vastly heterogeneous forms, whose clinical interpretation is, therefore, highly challenging. We set out to develop a novel unsupervised cluster analysis method in a large patient population. The objective was to analyze the main RYR1-related characteristics to identify distinctive features of RYR1-RM and, thus, offer more precise genotype-phenotype correlations in a group of potentially life-threatening disorders. We studied 600 patients presenting with a suspicion of inherited myopathy, who were investigated using next-generation sequencing. Among them, 73 index cases harbored variants in RYR1. In an attempt to group genetic variants and fully exploit information derived from genetic, morphological, and clinical datasets, we performed unsupervised cluster analysis in 64 probands carrying monoallelic variants. Most of the 73 patients with positive molecular diagnoses were clinically asymptomatic or pauci-symptomatic. Multimodal integration of clinical and histological data, performed using a non-metric multi-dimensional scaling analysis with k-means clustering, grouped the 64 patients into 4 clusters with distinctive patterns of clinical and morphological findings. In addressing the need for more specific genotype-phenotype correlations, we found clustering to overcome the limits of the "single-dimension" paradigm traditionally used to describe genotype-phenotype relationships.

Anatomical Laser Microdissection of the Ileum Reveals mtDNA Depletion Recovery in A Mitochondrial Neuro-Gastrointestinal Encephalomyopathy (MNGIE) Patient Receiving Liver Transplant.

mitochondrial neuro-gastrointestinal encephalomyopathy (MNGIE) is a rare genetic disorder characterized by thymidine phosphorylase (TP) enzyme defect. The absence of TP activity induces the imbalance of mitochondrial nucleotide pool, leading to impaired mitochondrial DNA (mtDNA) replication and depletion. Since mtDNA is required to ensure oxidative phosphorylation, metabolically active tissues may not achieve sufficient energy production. The only effective life-saving approach in MNGIE has been the permanent replacement of TP via allogeneic hematopoietic stem cell or liver transplantation. However, the follow-up of transplanted patients showed that gut tissue changes do not revert and fatal complications, such as massive gastrointestinal bleeding, can occur. The purpose of this study was to clarify whether the reintroduction of TP after transplant can recover mtDNA copy number in a normal range. Using laser capture microdissection and droplet-digital-PCR, we assessed the mtDNA copy number in each layer of full-thickness ileal samples of a naive MNGIE cohort vs. controls and in a patient pre- and post-TP replacement. The treatment led to a significant recovery of gut tissue mtDNA amount, thus showing its efficacy. Our results indicate that a timely TP replacement is needed to maximize therapeutic success before irreversible degenerative tissue changes occur in MNGIE.

Clinical-Genetic Features Influencing Disability in Spastic Paraplegia Type 4: A Cross-sectional Study by the Italian DAISY Network.

Background and Objectives: Hereditary spastic paraplegias (HSPs) are a group of inherited rare neurologic disorders characterized by length-dependent degeneration of the corticospinal tracts and dorsal columns, whose prominent clinical feature is represented by spastic gait. Spastic paraplegia type 4 (SPG4, SPAST-HSP) is the most common form. We present both clinical and molecular findings of a large cohort of patients, with the aim of (1) defining the clinical spectrum of SPAST-HSP in Italy; (2) describing their molecular features; and (3) assessing genotype-phenotype correlations to identify features associated with worse disability. Methods: A cross-sectional retrospective study with molecular and clinical data collected in an anonymized database was performed. Results: A total of 723 Italian patients with SPAST-HSP (58% men) from 316 families, with a median age at onset of 35 years, were included. Penetrance was 97.8%, with men showing higher Spastic Paraplegia Rating Scale (SPRS) scores (19.67 ± 12.58 vs 16.15 ± 12.61, p = 0.009). In 26.6% of patients with SPAST-HSP, we observed a complicated phenotype, mainly including intellectual disability (8%), polyneuropathy (6.7%), and cognitive decline (6.5%). Late-onset cases seemed to progress more rapidly, and patients with a longer disease course displayed a more severe neurologic disability, with higher SPATAX (3.61 ± 1.46 vs 2.71 ± 1.20, p < 0.001) and SPRS scores (22.63 ± 11.81 vs 12.40 ± 8.83, p < 0.001). Overall, 186 different variants in the SPAST gene were recorded, of which 48 were novel. Patients with SPAST-HSP harboring missense variants displayed intellectual disability (14.5% vs 4.4%, p < 0.001) more frequently, whereas patients with truncating variants presented more commonly cognitive decline (9.7% vs 2.6%, p = 0.001), cerebral atrophy (11.2% vs 3.4%, p = 0.003), lower limb spasticity (61.5% vs 44.5%), urinary symptoms (50.0% vs 31.3%, p < 0.001), and sensorimotor polyneuropathy (11.1% vs 1.1%, p < 0.001). Increasing disease duration (DD) and abnormal motor evoked potentials (MEPs) were also associated with increased likelihood of worse disability (SPATAX score>3). Discussion: The SPAST-HSP phenotypic spectrum in Italian patients confirms a predominantly pure form of HSP with mild-to-moderate disability in 75% of cases, and slight prevalence of men, who appeared more severely affected. Early-onset cases with intellectual disability were more frequent among patients carrying missense SPAST variants, whereas patients with truncating variants showed a more complicated disease. Both longer DD and altered MEPs are associated with worse disability.

Challenges and resources in adult life with Joubert syndrome: issues from an international classification of functioning (ICF) perspective.

BACKGROUND: Joubert Syndrome (JS) is a rare inherited neurodevelopmental disorder defined by a characteristic cerebellar and brainstem malformation (i.e. the molar tooth sign) and variable organ involvement. The aim of the present study was to describe functional limitations and disabilities in a large sample of adult patients with a diagnosis of JS. METHODS: We administered the International Classification of Functioning (ICF) checklist to thirty-six adult Italian patients with JS or their caregivers through telephone calls. RESULTS: None-to-mild impairment was documented for basic cognitive and mental functions, whereas severe deficit emerged for higher-order skills and language. A mismatch between individuals' capacity for daily activity and social participation and the actual performance in these fields emerged, suggesting that adults with JS may greatly benefit from external support from the caring environment. Indeed, specific facilitators were highlighted, including communication technologies as well as family members, healthcare professionals and peers support. Mild-to-severe barriers have been identified by adult patients with JS in the domains of services, systems and policies. CONCLUSIONS: These findings highlight challenges and barriers for adults with JS in areas of daily functioning that may be improved by investing in rehabilitation care models that embed social support programs and policies into clinical interventions.IMPLICATIONS FOR REHABILITATIONChildren with Joubert Syndrome, a child-onset rare inherited neurodevelopmental condition, are growing up and becoming adults; a life course approach in rehabilitation is needed;There is a substantial lack of information on the long-term adaptive daily functioning of children with a diagnosis of Joubert Syndrome;In this paper, the International Classification of Functioning (ICF) was applied to assess the daily functioning in people with JS;Severe deficits emerged for high-order skills and language, whereas the use of communication technologies and the engagement of family members were highlighted as key facilitators;These findings highlight the need for a change of paradigm in the care model of subjects with JS, with the embedding of social support in rehabilitation programs.

Episodic ataxia and severe infantile phenotype in spinocerebellar ataxia type 14: expansion of the phenotype and novel mutations.

INTRODUCTION: Spinocerebellar ataxia type 14 (SCA14) is a dominantly inherited neurological disorder characterized by slowly progressive cerebellar ataxia. SCA14 is caused by mutations in PRKCG, a gene encoding protein kinase C gamma (PKCγ), a master regulator of Purkinje cells development. METHODS: We performed next-generation sequencing targeted resequencing panel encompassing 273 ataxia genes in 358 patients with genetically undiagnosed ataxia. RESULTS: We identified fourteen patients in ten families harboring nine pathogenic heterozygous variants in PRKCG, seven of which were novel. We encountered four patients with not previously described phenotypes: one with episodic ataxia, one with a spastic paraparesis dominating her clinical manifestations, and two children with an unusually severe phenotype. CONCLUSIONS: Our study broadens the genetic and clinical spectrum of SCA14.

POLR3A variants in hereditary spastic paraparesis and ataxia: clinical, genetic, and neuroradiological findings in a cohort of Italian patients.

Mutations in POLR3A are characterized by high phenotypic heterogeneity, with manifestations ranging from severe childhood-onset hypomyelinating leukodystrophic syndromes to milder and later-onset gait disorders with central hypomyelination, with or without additional non-neurological signs. Recently, a milder phenotype consisting of late-onset spastic ataxia without hypomyelinating leukodystrophy has been suggested to be specific to the intronic c.1909 + 22G > A mutation in POLR3A. Here, we present 10 patients from 8 unrelated families with POLR3A-related late-onset spastic ataxia, all harboring the c.1909 + 22G > A variant. Most of them showed an ataxic-spastic picture, two a "pure" cerebellar phenotype, and one a "pure" spastic presentation. The non-neurological findings typically associated with POLR3A mutations were absent in all the patients. The main findings on brain MRI were bilateral hyperintensity along the superior cerebellar peduncles on FLAIR sequences, observed in most of the patients, and cerebellar and/or spinal cord atrophy, found in half of the patients. Only one patient exhibited central hypomyelination. The POLR3A mutations present in this cohort were the c.1909 + 22G > A splice site variant found in compound heterozygosity with six additional variants (three missense, two nonsense, one splice) and, in one patient, with a novel large deletion involving exons 14-18. Interestingly, this patient had the most "complex" presentation among those observed in our cohort; it included some neurological and non-neurological features, such as seizures, neurosensory deafness, and lipomas, that have not previously been reported in association with late-onset POLR3A-related disorders, and therefore further expand the phenotype.

NGS in Hereditary Ataxia: When Rare Becomes Frequent.

The term hereditary ataxia (HA) refers to a heterogeneous group of neurological disorders with multiple genetic etiologies and a wide spectrum of ataxia-dominated phenotypes. Massive gene analysis in next-generation sequencing has entered the HA scenario, broadening our genetic and clinical knowledge of these conditions. In this study, we employed a targeted resequencing panel (TRP) in a large and highly heterogeneous cohort of 377 patients with a clinical diagnosis of HA, but no molecular diagnosis on routine genetic tests. We obtained a positive result (genetic diagnosis) in 33.2% of the patients, a rate significantly higher than those reported in similar studies employing TRP (average 19.4%), and in line with those performed using exome sequencing (ES, average 34.6%). Moreover, 15.6% of the patients had an uncertain molecular diagnosis. STUB1, PRKCG, and SPG7 were the most common causative genes. A comparison with published literature data showed that our panel would have identified 97% of the positive cases reported in previous TRP-based studies and 92% of those diagnosed by ES. Proper use of multigene panels, when combined with detailed phenotypic data, seems to be even more efficient than ES in clinical practice.

Expert opinion on diagnosing, treating and managing patients with cerebrotendinous xanthomatosis (CTX): a modified Delphi study.

BACKGROUND: Cerebrotendinous xanthomatosis (CTX) is a rare, chronic, progressive, neurodegenerative disorder requiring life-long care. Patients with CTX often experience a diagnostic delay. Although early diagnosis and treatment initiation can improve symptoms and prognosis, a standardised approach to diagnosis, treatment and management of patients is not yet established. AIM: To assess expert opinion on best care practices for patients with CTX using a modified Delphi method. METHODS: A multidisciplinary group of healthcare professionals with expertise in CTX responded to a 3-round online questionnaire (n = 10 in Rounds 1 and 2; n = 9 in Round 3), containing questions relating to the diagnosis, treatment, monitoring, multidisciplinary care and prognosis of patients with CTX. Determination of consensus achievement was based on a pre-defined statistical threshold of ≥ 70% Delphi panellists selecting 1-2 (disagreement) or 5-6 (agreement) for 6-point Likert scale questions, or ≥ 70% Delphi panellists choosing the same option for ranking and proportion questions. RESULTS: Of the Round 1 (n = 22), Round 2 (n = 32) and Round 3 (n = 26) questions for which consensus was assessed, 59.1%, 21.9% and 3.8% reached consensus, respectively. Consensus agreement that genetic analyses and/or determination of serum cholestanol levels should be used to diagnose CTX, and dried bloodspot testing should facilitate detection in newborns, was reached. Age at diagnosis and early treatment initiation (at birth, where possible) were considered to have the biggest impact on treatment outcomes. All panellists agreed that chenodeoxycholic acid (CDCA) is a lifetime replacement therapy which, if initiated early, can considerably improve prognosis as it may be capable of reversing the pathophysiological process in CTX. No consensus was reached on the value of cholic acid therapy alone. Monitoring patients through testing plasma cholestanol levels and neurologic examination was recommended, although further research regarding monitoring treatment and progression of the disease is required. Neurologists and paediatricians/metabolic specialists were highlighted as key clinicians that should be included in the multidisciplinary team involved in patients' care. CONCLUSIONS: The results of this study provide a basis for standardisation of care and highlight key areas where further research is needed to inform best practices for the diagnosis, treatment and management of patients with CTX.

Evidence of enteric angiopathy and neuromuscular hypoxia in patients with mitochondrial neurogastrointestinal encephalomyopathy.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare autosomal recessive disease caused by thymidine phosphorylase (TP) enzyme defect. As gastrointestinal changes do not revert in patients undergone TP replacement therapy, one can postulate that other unexplored mechanisms contribute to MNGIE pathophysiology. Hence, we focused on the local TP angiogenic potential that has never been considered in MNGIE. In this study, we investigated the enteric submucosal microvasculature and the effect of hypoxia on fibrosis and enteric neurons density in jejunal full-thickness biopsies collected from patients with MNGIE. Orcein staining was used to count blood vessels based on their size. Fibrosis was assessed using the Sirius Red and Fast Green method. Hypoxia and neoangiogenesis were determined via hypoxia-inducible-factor-1α (HIF-1α) and vascular endothelial cell growth factor (VEGF) protein expression, respectively. Neuron-specific enolase was used to label enteric neurons. Compared with controls, patients with MNGIE showed a decreased area of vascular tissue, but a twofold increase of submucosal vessels/mm2 with increased small size and decreased medium and large size vessels. VEGF positive vessels, fibrosis index, and HIF-1α protein expression were increased, whereas there was a diminished thickness of the longitudinal muscle layer with an increased interganglionic distance and reduced number of myenteric neurons. We demonstrated the occurrence of an angiopathy in the GI tract of patients with MNGIE. Neoangiogenetic changes, as detected by the abundance of small size vessels in the jejunal submucosa, along with hypoxia provide a morphological basis to explain neuromuscular alterations, vasculature breakdown, and ischemic abnormalities in MNGIE.NEW & NOTEWORTHY Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is characterized by a genetically driven defect of thymidine phosphorylase, a multitask enzyme playing a role also in angiogenesis. Indeed, major gastrointestinal bleedings are life-threatening complications of MNGIE. Thus, we focused on jejunal submucosal vasculature and showed intestinal microangiopathy as a novel feature occurring in this disease. Notably, vascular changes were associated with neuromuscular abnormalities, which may explain gut dysfunction and help to develop future therapeutic approaches in MNGIE.

Longitudinal changes in MoCA performances in patients with mild cognitive impairment and small vessel disease. Results from the VMCI-Tuscany Study.

Objectives: The Montreal Cognitive Assessment (MoCA) is a cognitive screening test largely employed in vascular cognitive impairment, but there are no data about MoCA longitudinal changes in patients with cerebral small vessel disease (SVD). We aimed to describe changes in MoCA performance in patients with mild cognitive impairment (MCI) and SVD during a 2-year follow-up, and to evaluate their association with transition to major neurocognitive disorder (NCD). Materials and Methods: Within the prospective observational VMCI-Tuscany Study, patients with MCI and SVD underwent a comprehensive clinical, neuropsychological, and functional evaluation at baseline, and after 1 and 2 years. Results: Among the 138 patients (mean age 74.4 ± 6.9 years; males: 57%) who completed the study follow-up, 44 (32%) received a major NCD diagnosis. Baseline MoCA scores (mean±SD) were lower in major NCD patients (20.5 ± 5) than in reverter/stable MCI (22.2 ± 4.3), and the difference approached the statistical threshold of significance (p=.051). The total cohort presented a decrease in MoCA score (mean±SD) of -1.3 ± 4.2 points (-2.6 ± 4.7 in major NCD patients, -0.7 ± 3.9 in reverter/stable MCI). A multivariate logistic model on the predictors of transition from MCI to major NCD, showed MoCA approaching the statistical significance (OR=1.09, 95% CI=1.00-1.19, p=.049). Discussion: In our sample of MCI patients with SVD, longitudinal changes in MoCA performances were consistent with an expected more pronounced deterioration in patients who received a diagnosis of major NCD. MoCA sensitivity to change and predictive utility need to be further explored in VCI studies based on larger samples and longer follow-up periods.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE): Position paper on diagnosis, prognosis, and treatment by the MNGIE International Network.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare autosomal recessive disease caused by TYMP mutations and thymidine phosphorylase (TP) deficiency. Thymidine and deoxyuridine accumulate impairing the mitochondrial DNA maintenance and integrity. Clinically, patients show severe and progressive gastrointestinal and neurological manifestations. The onset typically occurs in the second decade of life and mean age at death is 37 years. Signs and symptoms of MNGIE are heterogeneous and confirmatory diagnostic tests are not routinely performed by most laboratories, accounting for common misdiagnosis. Factors predictive of progression and appropriate tests for monitoring are still undefined. Several treatment options showed promising results in restoring the biochemical imbalance of MNGIE. The lack of controlled studies with appropriate follow-up accounts for the limited evidence informing diagnostic and therapeutic choices. The International Consensus Conference (ICC) on MNGIE, held in Bologna, Italy, on 30 March to 31 March 2019, aimed at an evidence-based consensus on diagnosis, prognosis, and treatment of MNGIE among experts, patients, caregivers and other stakeholders involved in caring the condition. The conference was conducted according to the National Institute of Health Consensus Conference methodology. A consensus development panel formulated a set of statements and proposed a research agenda. Specifically, the ICC produced recommendations on: (a) diagnostic pathway; (b) prognosis and the main predictors of disease progression; (c) efficacy and safety of treatments; and (f) research priorities on diagnosis, prognosis, and treatment. The Bologna ICC on diagnosis, management and treatment of MNGIE provided evidence-based guidance for clinicians incorporating patients' values and preferences.

Case Report: Early Treatment With Chenodeoxycholic Acid in Cerebrotendinous Xanthomatosis Presenting as Neonatal Cholestasis.

Background: Cerebrotendinous xanthomatosis (CTX) is an inborn disorder of bile acid synthesis which causes progressive accumulation of toxic metabolites in various organs, particularly in brain and tendons. Most cases are diagnosed and treated in the second or third decade of life, when neurological involvement appears. We describe a case of CTX presenting as neonatal cholestasis. Results: The child presented cholestasis at 2 months of life. In the following months jaundice slowly disappeared, with a normalization of bilirubin and aminotransferases, respectively, at 6 and 8 months. A LC-Mass Spectrometry of the urines showed the presence of cholestanepentols glucuronide, which led to the suspicion of cerebrotendinous xanthomatosis. The diagnosis was confirmed by the dosage of cholestanol in serum and the molecular genetic analysis of the CYP27A1 gene. Therapy with chenodeoxycholic acid (CDCA) was started at 8 months and is still ongoing. The child was monitored for 13 years by dosage of serum cholestanol and urinary cholestanepentols. A strictly biochemical and neurological follow up was performed and no sign of neurological impairment was observed. Conclusions: Prompt diagnosis and treatment of CTX presenting as neonatal cholestasis may prevent further neurological impairment.

Liver transplantation in mitochondrial neurogastrointestinal encephalomyopathy (MNGIE): clinical long-term follow-up and pathogenic implications.

We report the longest follow-up of clinical and biochemical features of two previously reported adult mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) patients treated with liver transplantation (LT), adding information on a third, recently transplanted, patient. All three patients overcame the early post-operative period and tolerated immunosuppressive therapy. Plasma nucleoside levels dramatically decreased, with evidence of clinical improvement of ambulation and neuropathy. Conversely, other features of MNGIE, as gastrointestinal dysmotility, low weight, ophthalmoparesis, and leukoencephalopathy were essentially unchanged. A similar picture characterized two patients treated with allogenic hematopoietic stem cell transplantation (AHSCT). In conclusion, LT promptly and stably normalizes nucleoside imbalance in MNGIE, stabilizing or improving some clinical parameters with marginal periprocedural mortality rate as compared to AHSCT. Nevertheless, restoring thymidine phosphorylase (TP) activity, achieved by both LT and AHSCT, does not allow a full clinical recovery, probably due to consolidated cellular damage and/or incomplete enzymatic tissue replacement.

Fibroblast growth factor 21 and grow differentiation factor 15 are sensitive biomarkers of mitochondrial diseases due to mitochondrial transfer-RNA mutations and mitochondrial DNA deletions.

BACKGROUND: Diagnosis of mitochondrial diseases (MDs) is challenging, since they are multisystemic disorders, characterized by a heterogeneous symptomatology. Recently, an increase in serum levels of fibroblast growth factor 21 (FGF21) and growth differentiation factor 15 (GDF15) has been found in the majority of patients with MDs compared with healthy controls. On the other hand, the finding of low FGF21 and GDF15 levels in some patients with MDs suggests that different types of respiratory chain defects may lead to different profiles of these two proteins. OBJECTIVE: In this study, we aimed to validate the diagnostic reliability of FGF21 and GDF15 assays in MDs and to evaluate a possible correlation between serum levels of the two biomarkers with genotype of MD patients. Serum FGF21 and GDF15 levels were measured by a quantitative ELISA. RESULTS: Our results showed increased serum FGF21 and GDF15 levels in MD patients; however, GDF15 measurement seems to be more sensitive and specific for screening tests for MD than FGF21. Moreover, we showed a positive correlation with both FGF21 and GDF15 levels and the number of COX-negative fibers. CONCLUSION: Finally, we also demonstrated that the increase of FGF21 and GDF15 was related to MDs caused by mitochondrial translation defects, and multiple and single mtDNA deletions, but not to MDs due to mutations in the respiratory chain subunits.

Multi-imaging study in a patient with cerebrotendinous xanthomatosis: radiology, clinic and pathology correlation of a rare condition.

Cerebrotendinous xanthomatosis (CTX) is a rare metabolic disease with autosomal recessive inheritance. It is caused by mutations of the CYP27A1 gene, which codifies for sterol 27-hydroxylase, an enzyme that is responsible for the synthesis of cholic acids. In CTX, cholic acid synthesis is impaired, leading to accumulation of the precursor chenodessossicholic acid) in various organs and tissues. The clinical manifestations of CTX include chronic diarrhea, early-onset cataracts, tendon xanthomas and neurological disturbances. Therapy with oral chenodessossicholic acid has been shown to provide significantly better outcomes for affected individuals; therefore, recognition of this disease and awareness of its suggestive instrumental signs is extremely important. In this study, we describe the imaging findings in a 43-years-old male who was diagnosed with CTX and studied through ultrasound, CT and MRI. It is important that the neurology and radiology communities are aware of this multi-imaging findings: recognition of them is important, as due to the high variability of the manifestation of this disease; it could impact on early diagnosis of a condition rarely seen, but manageable.

Eye movement changes in autosomal dominant spinocerebellar ataxias.

Oculomotor abnormalities are common findings in spinocerebellar ataxias (SCAs), a clinically heterogeneous group of neurodegenerative disorders with an autosomal dominant pattern of inheritance. Usually, cerebellar impairment accounts for most of the eye movement changes encountered; as the disease progresses, the involvement of extracerebellar structures typically seen in later stages may modify the oculomotor progression. However, ocular movement changes are rarely specific. In this regard, some important exceptions include the prominent slowing of horizontal eye movements in SCA2 and, to a lesser extent, in SCA3, SCA4, and SCA28, or the executive deficit in SCA2 and SCA17. Here, we report the eye movement abnormalities and neurological pictures of SCAs through a review of the literature. Genetic and neuropathological/neuroimaging aspects are also briefly discussed. Overall, the findings reported indicate that oculomotor analysis could be of help in differential diagnosis among SCAs and contribute to clarify the role of brain structures, particularly the cerebellum, in oculomotor control.

HTRA1 expression profile and activity on TGF-ß signaling in HTRA1 mutation carriers.

High temperature requirement A1 (HTRA1) is a serine protease playing a modulatory role in various cell processes, particularly in the regulation of transforming growth factor-ß (TGF-ß) signaling. A deleterious role in late-onset cerebral small vessel diseases (CSVDs) of heterozygous HTRA1 mutations, otherwise causative in homozygosity of cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy, was recently suggested. However, the pathomechanism of these heterozygous mutations is still undefined. Our aim is to evaluate the expression profile and activity of HTRA1 on TGF-ß signaling in fibroblasts from four subjects carrying the HTRA1 heterozygous mutations-p.E42Dfs*173, p.A321T, p.G295R, and p.Q151K. We found a 50% reduction of HTRA1 expression in HTRA1 mutation carriers compared to the control. Moreover, we showed no changes in TGF-ß signaling pathway downstream intermediate, Phospho Smad2/3. However, we found overexpression of genes involved in the extracellular matrix formation in two heterozygous HTRA1 carriers. Our results suggest that each heterozygous HTRA1 missense mutation displays a different and peculiar HTRA1 expression pattern and that CSVD phenotype may also result from 50% of HTRA1 expression.

The safety and effectiveness of chenodeoxycholic acid treatment in patients with cerebrotendinous xanthomatosis: two retrospective cohort studies.

OBJECTIVE: To evaluate the safety and effectiveness of chenodeoxycholic acid (CDCA) treatment in patients with cerebrotendinous xanthomatosis (CTX). METHODS: Two retrospective cohort studies were conducted in CTX patients who underwent CDCA treatment: one in the Netherlands (NL; CDCA-STUK-15-001) and one in Italy (IT; CDCA-STRCH-CR-14-001). Eligible patients were aged 2-75 years, had been diagnosed with CTX, and were treated with CDCA orally for ≥1 year. The impact of CDCA treatment on biochemical markers (including serum cholestanol levels) and disease signs and symptoms were assessed, in addition to the safety and tolerability of CDCA treatment. RESULTS: A total of 35 patients were screened in the NL study and were diagnosed with CTX at 25.6 (± 13.7 SD) years on average. These patients were treated with CDCA and followed up for a median of 9.00 (range: 0.4-26.3) years. In addition, 28 patients were enrolled in the IT study and were diagnosed at 35.0 (± 11.4 SD) years on average (median duration of CDCA treatment: 5.75 [range: 0.0-25.0] years). Signs and symptoms of disease resolved, improved, or remained stable in many patients, with concomitant improvements in biochemical marker levels (serum cholestanol, p < 0.001; 7α-hydroxy-4-cholesten-3-one, p < 0.001 [IT study]). CONCLUSIONS: The outcomes of these retrospective cohort studies indicate that CDCA is effective in the long-term treatment of CTX, with an acceptable safety profile.

Nonsense mutations in alpha-II spectrin in three families with juvenile onset hereditary motor neuropathy.

Distal hereditary motor neuropathies are a rare subgroup of inherited peripheral neuropathies hallmarked by a length-dependent axonal degeneration of lower motor neurons without significant involvement of sensory neurons. We identified patients with heterozygous nonsense mutations in the αII-spectrin gene, SPTAN1, in three separate dominant hereditary motor neuropathy families via next-generation sequencing. Variable penetrance was noted for these mutations in two of three families, and phenotype severity differs greatly between patients. The mutant mRNA containing nonsense mutations is broken down by nonsense-mediated decay and leads to reduced protein levels in patient cells. Previously, dominant-negative αII-spectrin gene mutations were described as causal in a spectrum of epilepsy phenotypes.