Heterodisomy in the locus is also a cause of pseudohypoparathyroidism type 1B (iPPSD3).

Objective: To identify the genetic cause underlying the methylation defect in a patient with clinical suspicion of PHP1B/iPPSD3.

Design: Imprinting is an epigenetic mechanism that allows the regulation of gene expression. The locus is one of the loci within the genome that is imprinted.

Uncovering the electrical synapse proteome in retinal neurons via in vivo proximity labeling.

Electrical synapses formed by Connexin 36 (Cx36) serve as a fast means for communication in the nervous systems. Only little is known about the protein complexes that constitute these synapses. In the present study, we applied different BioID strategies to screen the interactomes of Connexin 36 the major neuronal connexin and its zebrafish orthologue Cx35b in retinal neurons.

Expansion Microscopy of Synaptic Contacts on the Mauthner Cells of Larval Zebrafish.

Because of its genetic tractability and amenability for live imaging, larval zebrafish () have emerged as a model to study the cellular and synaptic properties underlying behavior. The accessibility of Mauthner cells, a pair of escape-organizing neurons located in the brainstem of teleost fish, along with their associated sensory inputs, enables exploration of the correlation between structural and functional synaptic features. This is the case of the endings of auditory afferents on the lateral dendrite of this cell, known as large myelinated club endings, which provide the excitatory drive for the initiation of auditory-evoked escape responses mediated by the Mauthner cell and its spinal network.

Multi-locus imprinting disturbance (MLID): interim joint statement for clinical and molecular diagnosis.

Background: Imprinting disorders are rare diseases resulting from altered expression of imprinted genes, which exhibit parent-of-origin-specific expression patterns regulated through differential DNA methylation. A subgroup of patients with imprinting disorders have DNA methylation changes at multiple imprinted loci, a condition referred to as multi-locus imprinting disturbance (MLID). MLID is recognised in most but not all imprinting disorders and is also found in individuals with atypical clinical features; the presence of MLID often alters the management or prognosis of the affected person.

The components of an electrical synapse as revealed by expansion microscopy of a single synaptic contact.

Most nervous systems combine both transmitter-mediated and direct cell-cell communication, known as 'chemical' and 'electrical' synapses, respectively. Chemical synapses can be identified by their multiple structural components. Electrical synapses are, on the other hand, generally defined by the presence of a 'gap junction' (a cluster of intercellular channels) between two neuronal processes.

Choosing the Best Tissue and Technique to Detect Mosaicism in Fibrous Dysplasia/McCune-Albright Syndrome (FD/MAS).

-activating somatic mutations give rise to Fibrous Dysplasia/McCune-Albright syndrome (FD/MAS). The low specificity of extra-skeletal signs of MAS and the mosaic status of the mutations generate some difficulties for a proper diagnosis. We studied the clinical and molecular statuses of 40 patients referred with a clinical suspicion of FD/MAS to provide some clues.

Incidental finding at methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA): how to proceed?

Since the advent of new generation sequencing, professionals are aware of the possibility of obtaining findings unrelated to the pathology under study. However, this possibility is usually forgotten in the case of studies aimed at a single gene or region. We report a case of a 16-month-old girl with clinical suspicion of Silver-Russell syndrome (SRS).

The components of an electrical synapse as revealed by expansion microscopy of a single synaptic contact.

Most nervous systems combine both transmitter-mediated and direct cell-cell communication, known as 'chemical' and 'electrical' synapses, respectively. Chemical synapses can be identified by their multiple structural components. Electrical synapses are, on the other hand, generally defined by the presence of a 'gap junction' (a cluster of intercellular channels) between two neuronal processes.

Vitamin D deficiency in adulthood: Presentation of 2familial cases simulating pseudohypoparathyroidism.

Background And Objective: The clinical and biochemical overlap of various pathologies of phosphocalcic metabolism can lead to misdiagnosis and consequent clinical management. One example is pseudohypoparathyroidism, which can be confused with vitamin D-dependent rickets (VDDR1) if appropriate biochemical determinations are not performed.

Patients And Methods: Two pairs of siblings, from independent families, were clinically diagnosed in adolescence with pseudohypoparathyroidism due to hypocalcaemia, elevated parathyroid hormone levels and normal or elevated phosphorus values.

South American H4N2 influenza A virus improved replication in chicken trachea after low number of passages.

Introduction of influenza A viruses (FLUAV) into poultry from waterfowl is frequent, producing economic burden and increasing the probability of human infections. We have previously described the presence of FLUAV in wild birds in Argentina with unique evolutionary trajectories belonging to a South American lineage different from the North American and Eurasian lineages. Adaptability of this South American lineage FLUAV to poultry species is still poorly understood.

Growth patterns and outcomes of growth hormone therapy in patients with acrodysostosis.

Introduction: Severe short stature is a feature of acrodysostosis, but data on growth are sparse. Treatment with recombinant human growth hormone (rhGH) is used in some centers to increase final height, but no studies have been published so far. Our objective was to conduct a multicenter, retrospective, cohort study to investigate growth in individuals with both types of acrodysostosis, treated with rhGH or not; we used the new nomenclature to describe acrodysostosis, as this disease belongs to the large group of inactivating PTH/PTHrP signaling disorders (iPPSD); acrodysostosis refers to iPPSD4 (acrodysostosis type 1 due to PRKAR1A mutations) and iPPSD5 (acrodysostosis type 2, due to PDE4D mutations).

Propriospinal myoclonus: diagnostic value of polymyography and video polysomnography.

Unlabelled: Propriospinal myoclonus is a hyperkinetic movement disorder characterized by painless jerks of the axial muscles, mainly in the trunk and hips. A 53-year-old woman was referred to the Sleep Unit with trunk flexion movements in the supine position during the wake-sleep transition and during sleep, with premonitory sensation. We performed 2 video polysomnographic recordings.

Frequency of variants and parental mosaicism in families with inactivating PTH/PTHrP signaling disorder type 2.

Objective: iPPSD2 (which includes PHP1A and PPHP/POH) is a rare inherited autosomal dominant endocrine disorder caused by inactivating pathogenic variants. A high percentage of cases has been suggested. In rare cases, parental mosaicism has been described, but its real frequency is unknown.

Analysis of a large case series of fatal familial insomnia to determine tests with the highest diagnostic value.

Fatal familial insomnia (FFI) is a rare prionopathy with unusually high incidence in the Basque Country. We report detailed data on clinical, diagnostic, histopathological, and biochemical characteristics of a recent FFI case series. The Basque Brain Bank database was screened for patients diagnosed from 2010 to 2021 with standard genetic and/or neuropathological criteria.

First step towards a consensus strategy for multi-locus diagnostic testing of imprinting disorders.

Background: Imprinting disorders, which affect growth, development, metabolism and neoplasia risk, are caused by genetic or epigenetic changes to genes that are expressed from only one parental allele. Disease may result from changes in coding sequences, copy number changes, uniparental disomy or imprinting defects. Some imprinting disorders are clinically heterogeneous, some are associated with more than one imprinted locus, and some patients have alterations affecting multiple loci.

Novel genetic variants of KHDC3L and other members of the subcortical maternal complex associated with Beckwith-Wiedemann syndrome or Pseudohypoparathyroidism 1B and multi-locus imprinting disturbances.

Background: Beckwith-Wiedemann syndrome (BWS) and Pseudohypoparathyroidism type 1B (PHP1B) are imprinting disorders (ID) caused by deregulation of the imprinted gene clusters located at 11p15.5 and 20q13.32, respectively.

Recording Synaptic Transmission from Auditory Mixed Synapses on the Mauthner Cells of Developing Zebrafish.

The Mauthner cells are a pair of large reticulospinal neurons that organize sensory-evoked tail flip responses in fishes. An identifiable group of auditory "mixed" (electrical and chemical) synaptic contacts known as "Large Myelinated Club endings" on these cells have provided a valuable model for the study of synaptic transmission in the vertebrate brain. While most of studies were performed in adult fish, we describe here methods that make possible recording synaptic transmission from these contacts in developing zebrafish, a genetically tractable vertebrate species which is uniquely amenable for combining synaptic physiology with live imaging and behavioral analysis.

Trans-acting genetic variants causing multilocus imprinting disturbance (MLID): common mechanisms and consequences.

Background: Imprinting disorders are a group of congenital diseases which are characterized by molecular alterations affecting differentially methylated regions (DMRs). To date, at least twelve imprinting disorders have been defined with overlapping but variable clinical features including growth and metabolic disturbances, cognitive dysfunction, abdominal wall defects and asymmetry. In general, a single specific DMR is affected in an individual with a given imprinting disorder, but there are a growing number of reports on individuals with so-called multilocus imprinting disturbances (MLID), where aberrant imprinting marks (most commonly loss of methylation) occur at multiple DMRs.

Description of the first Spanish case of Gerstmann-Sträussler-Scheinker disease with A117V variant: clinical, histopathological and biochemical characterization.

Gerstmann-Sträussler-Scheinker disease (GSS) is a rare neurodegenerative illness that belongs to the group of hereditary or familial Transmissible Spongiform Encephalopathies (TSE). Due to the presence of different pathogenic alterations in the prion protein (PrP) coding gene, it shows an enhanced proneness to misfolding into its pathogenic isoform, leading to prion formation and propagation. This aberrantly folded protein is able to induce its conformation to the native counterparts forming amyloid fibrils and plaques partially resistant to protease degradation and showing neurotoxic properties.

Trichloroacetic Acid Fixation and Antibody Staining of Zebrafish Larvae.

Larval zebrafish have been established as an excellent model for examining vertebrate biology, with many researchers using the system for neuroscience. Controlling a fast escape response of the fish, the Mauthner cells and their associated network are an attractive model, given their experimental accessibility and fast development, driving ethologically relevant behavior in the first five days of development. Here, we describe methods for immunostaining electrical and chemical synapse proteins at 3-7 days post fertilization (dpf) in zebrafish using tricholoracetic acid fixation.

On the location of electrical synapses.

Location is of critical functional relevance for synapses, including electrical synapses, which are a form of neuronal communication mediated by cell-cell channels. In this issue of Developmental Cell, Palumbos et al. identify a mechanism that supports the localization and function of electrical synapses with subcellular specificity.