A common flanking variant is associated with enhanced stability of the FGF14-SCA27B repeat locus.

The factors driving or preventing pathological expansion of tandem repeats remain largely unknown. Here, we assessed the FGF14 (GAA)·(TTC) repeat locus in 2,530 individuals by long-read and Sanger sequencing and identified a common 5'-flanking variant in 70.34% of alleles analyzed (3,463/4,923) that represents the phylogenetically ancestral allele and is present on all major haplotypes. This common sequence variation is present nearly exclusively on nonpathogenic alleles with fewer than 30 GAA-pure triplets and is associated with enhanced stability of the repeat locus upon intergenerational transmission and increased Fiber-seq chromatin accessibility.

Somatic instability of the FGF14 -SCA27B GAA•TTC repeat reveals a marked expansion bias in the cerebellum.

Spinocerebellar ataxia 27B (SCA27B) is a common autosomal dominant ataxia caused by an intronic GAA•TTC repeat expansion in FGF14 . Neuropathological studies have shown that neuronal loss is largely restricted to the cerebellum. Although the repeat locus is highly unstable during intergenerational transmission, it remains unknown whether it exhibits cerebral mosaicism and progressive instability throughout life. We conducted an analysis of the FGF14 GAA•TTC repeat somatic instability across 156 serial blood samples from 69 individuals, fibroblasts, induced pluripotent stem cells, and post-mortem brain tissues from six controls and six patients with SCA27B, alongside methylation profiling using targeted long-read sequencing. Peripheral tissues exhibited minimal somatic instability, which did not significantly change over periods of more than 20 years. In post-mortem brains, the GAA•TTC repeat was remarkably stable across all regions, except in the cerebellar hemispheres and vermis. The levels of somatic expansion in the cerebellar hemispheres and vermis were, on average, 3.15 and 2.72 times greater relative to other examined brain regions, respectively. Additionally, levels of somatic expansion in the brain increased with repeat length and tissue expression of FGF14 . We found no significant difference in methylation of wild-type and expanded FGF14 alleles in post-mortem cerebellar hemispheres between patients and controls. In conclusion, our study revealed that the FGF14 GAA•TTC repeat exhibits a cerebellar-specific expansion bias, which may explain the pure and late-onset cerebellar involvement in SCA27B.

Case report: A novel biallelic FTO variant causing multisystem anomalies with severe epilepsy, widening the spectrum of FTO syndrome.

The fat mass and obesity-associated gene (FTO) codes for a DNA/RNA demethylase. Pathological variants in this gene are rare, with only three reports in the literature, all with mutations in the catalytic domain. We report the first biallelic human variant in fat mass and obesity-associated gene (c.287G>C, p.Arg96Pro/R96P) outside the catalytic site, causing numerous abnormalities across multiple organ systems, affecting respiratory, cardiovascular, and neurological function. Biochemical assays of cells with the patient's variant were performed to further quantify the effect of the variant on function. Loss-of-function resulting from the patient's R96P missense variant was demonstrated with in vitro biochemical characterization of demethylase activity, resulting in a 90% reduction in function of the fat mass and obesity-associated protein compared to wild-type. Our findings demonstrate a novel fat mass and obesity-associated gene non-catalytic site variant with a unique patient phenotype of bilateral multifocal epilepsy and multisystem congenital anomalies.

A wearable motion capture suit and machine learning predict disease progression in Friedreich's ataxia.

Friedreich's ataxia (FA) is caused by a variant of the Frataxin (FXN) gene, leading to its downregulation and progressively impaired cardiac and neurological function. Current gold-standard clinical scales use simplistic behavioral assessments, which require 18- to 24-month-long trials to determine if therapies are beneficial. Here we captured full-body movement kinematics from patients with wearable sensors, enabling us to define digital behavioral features based on the data from nine FA patients (six females and three males) and nine age- and sex-matched controls, who performed the 8-m walk (8-MW) test and 9-hole peg test (9 HPT). We used machine learning to combine these features to longitudinally predict the clinical scores of the FA patients, and compared these with two standard clinical assessments, Spinocerebellar Ataxia Functional Index (SCAFI) and Scale for the Assessment and Rating of Ataxia (SARA). The digital behavioral features enabled longitudinal predictions of personal SARA and SCAFI scores 9 months into the future and were 1.7 and 4 times more precise than longitudinal predictions using only SARA and SCAFI scores, respectively. Unlike the two clinical scales, the digital behavioral features accurately predicted FXN gene expression levels for each FA patient in a cross-sectional manner. Our work demonstrates how data-derived wearable biomarkers can track personal disease trajectories and indicates the potential of such biomarkers for substantially reducing the duration or size of clinical trials testing disease-modifying therapies and for enabling behavioral transcriptomics.

Deconstructive repair of a traumatic vertebrovertebral arteriovenous fistula via a contralateral endovascular approach.

Vertebrovertebral arteriovenous fistulas (VVAVFs) are rare entities that lack consensus guidelines for their management. Our case describes the successful treatment of a traumatic VVAVF via a contralateral deconstructive endovascular approach. A 64-year-old female presented following a traumatic fall. Computed tomography angiogram highlighted a 2 cm pseudoaneurysm of the right vertebral artery (VA) with epidural contrast enhancement and a hematoma with flow voids within the epidural space. Digital subtraction angiography showed a VVAVF at C2-3 with retrograde filling of the distal right VA. Having undergone several unsuccessful passes of the proximal dissection flap in the right VA, the patient underwent a contralateral deconstructive approach with correction of the VVAVF without complication. The remaining feeding branches had occluded after 1 week. The patient made a complete recovery without neurological sequelae at 3-month follow-up.

To Be or Not to Be Eisenmenger: The Different Shades of Blue.

Eisenmenger syndrome refers to any untreated congenital cardiac defect with an intracardiac communication that leads to pulmonary arterial hypertension, reversal of intracardiac shunting, and cyanosis. We describe a 40-year-old cyanotic patient with congenital heart disease with presumed Eisenmenger syndrome who was considered inoperable. Testing revealed a partial atrioventricular septal defect with no evidence of pulmonary arterial hypertension, and the patient underwent successful cardiac repair. (Level of Difficulty: Intermediate.).

CRISPR Guide RNA Cloning for Mammalian Systems.

The outlined protocol describes streamlined methods for the efficient and cost-effective generation of Cas9-associated guide RNAs. Two alternative strategies for guide RNA (gRNA) cloning are outlined based on the usage of the Type IIS restriction enzyme BsmBI in combination with a set of compatible vectors. Outside of the access to Sanger sequencing services to validate the generated vectors, no special equipment or reagents are required aside from those that are standard to modern molecular biology laboratories. The outlined method is primarily intended for cloning one single gRNA or one paired gRNA-expressing vector at a time. This procedure does not scale well for the generation of libraries containing thousands of gRNAs. For those purposes, alternative sources of oligonucleotide synthesis such as oligo-chip synthesis are recommended. Finally, while this protocol focuses on a set of mammalian vectors, the general strategy is plastic and is applicable to any organism if the appropriate gRNA vector is available.

Transcriptional Activation of Pericentromeric Satellite Repeats and Disruption of Centromeric Clustering upon Proteasome Inhibition.

Heterochromatinisation of pericentromeres, which in mice consist of arrays of major satellite repeats, are important for centromere formation and maintenance of genome stability. The dysregulation of this process has been linked to genomic stress and various cancers. Here we show in mice that the proteasome binds to major satellite repeats and proteasome inhibition by MG132 results in their transcriptional de-repression; this de-repression is independent of cell-cycle perturbation. The transcriptional activation of major satellite repeats upon proteasome inhibition is accompanied by delocalisation of heterochromatin protein 1 alpha (HP1α) from chromocentres, without detectable change in the levels of histone H3K9me3, H3K4me3, H3K36me3 and H3 acetylation on the major satellite repeats. Moreover, inhibition of the proteasome was found to increase the number of chromocentres per cell, reflecting destabilisation of the chromocentre structures. Our findings suggest that the proteasome plays a role in maintaining heterochromatin integrity of pericentromeres.

Epigenetics and Triplet-Repeat Neurological Diseases.

The term "junk DNA" has been reconsidered following the delineation of the functional significance of repetitive DNA regions. Typically associated with centromeres and telomeres, DNA repeats are found in nearly all organisms throughout their genomes. Repetitive regions are frequently heterochromatinized resulting in silencing of intrinsic and nearby genes. However, this is not a uniform rule, with several genes known to require such an environment to permit transcription. Repetitive regions frequently exist as dinucleotide, trinucleotide, and tetranucleotide repeats. The association between repetitive regions and disease was emphasized following the discovery of abnormal trinucleotide repeats underlying spinal and bulbar muscular atrophy (Kennedy's disease) and fragile X syndrome of mental retardation (FRAXA) in 1991. In this review, we provide a brief overview of epigenetic mechanisms and then focus on several diseases caused by DNA triplet-repeat expansions, which exhibit diverse epigenetic effects. It is clear that the emerging field of epigenetics is already generating novel potential therapeutic avenues for this group of largely incurable diseases.

An atypical case of purple glove syndrome: an avoidable adverse event.

A 73-year-old man presented in status epilepticus. He had a long history of epilepsy for which he was treated with regular phenytoin and phenobarbitone. On admission, his phenytoin level was found to be subtherapeutic and was treated with rectal diazepam and intravenous lorazepam. He was later started on an infusion of phenytoin in preparation to restart his oral medication. The medication was delivered via a peripheral cannula in his forearm. Five days later, he developed redness and swelling of this arm followed by the appearance of a large ulcer. After ruling out infective causes and a compartment syndrome it was felt that the patient had developed a delayed purple glove syndrome secondary to intravenous phenytoin. Following 7 days of regular saline irrigation and dressing changes, the erythema improved and the ulcer showed signs of healing, and eventually resolved.

Hypergammaglobulinemia, normal serum albumin and hypercalcaemia: a case of systemic sarcoidosis with initial diagnostic confusion.

A 53-year-old Afro-Caribbean woman presented to casualty with a constellation of symptoms pointing to a diagnosis of hypercalcaemia. This was confirmed on laboratory investigation. Findings of a raised serum protein (108 g/l) and normal albumin (35 g/l), lead to an initial working diagnosis of multiple myeloma. However, later serum protein electrophoresis found a polyclonal gammopathy and further investigation lead to a diagnosis of sarcoidosis. The patient responded well to conventional treatment with oral prednisolone. A number of learning points have been highlighted including the pitfalls of pattern recognition in diagnosis and the various manifestations of systemic sarcoidosis. A brief review of the history and various manifestations of sarcoidosis including the pathophysiology of hypercalcaemia in sarcoidosis are presented as well as of polyclonal gammopathy.

Management of DYT1 dystonia throughout pregnancy.

A 30-year-old woman with generalised DYT1 dystonia, controlled with medication, presented at 9 weeks gestation with an unplanned pregnancy. A number of learning points were highlighted in management of the patient's dystonia alongside pregnancy including avoidance of excessive medication exposure to the fetus, while maintaining symptom control to a level acceptable and safe for the patient and prenatal diagnostic testing. In our case there was no overt ill effect to the newborn. This is a common worry among pregnant women with dystonia and as such the authors felt it important to report.