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Introduction: Ryanodine receptor type 1-related myopathies (RYR1-RM) represent the most prevalent category of congenital myopathies. The introduction of genetic techniques has shifted the diagnostic paradigm, suggesting the prioritization of molecular studies over biopsies. This study aims to explore the clinical and epidemiological characteristics of patients with RYR1 gene variants in a tertiary pediatric hospital, intending to enhance the understanding of the genotype-phenotype correlation in RYR1-RM., Patients and Methods: An observational, descriptive, and cross-sectional study was conducted on patients under 14 years old with myopathic symptoms and potentially pathogenic RYR1 gene variants from January 2013 to December 2023. Variables such as gender, age, motor development, genetic variants, inheritance pattern, and other manifestations were considered. All variables were tabulated against the genetic variant., Results: Of the nine included patients, the estimated incidence was approximately 1 in 10,000 live births. The median age at diagnosis was six years, with significant phenotypic variability. Common symptoms such as weakness and delayed motor development were observed. Genetic variants affected the RYR1 gene diversely, including five previously undescribed variants. Muscle biopsy was performed in five patients, revealing central core myopathy in two, multiminicore in one, congenital fiber-type disproportion in one, and a nonspecific pattern in another., Conclusions: RYR1-RM in our series exhibited phenotypic and involvement variability, with an incidence in our area of around 1 in 10,000 live births. Most cases were male, with dominant missense variants. We contribute five previously undescribed genetic variants.

Introduction: KIF1A-associated-neurological-disorder (KAND) encephalopathy is a group of progressive neurodegenerative pathologies of varying severity caused by mutations in the KIF1A gene (Kinesin family member 1A) located on chromosome 2q37.3. This gene encodes a protein of the kinesin-3 family that participates in the ATP-dependent anterograde transport of presynaptic vesicles through neuronal microtubules., Case Report: Four patients are described, aged 1-13 years, with a median onset of symptoms of 5 months (IQR 0-11 months), which represents an approximate prevalence of 1 per 64,000 children under 14 years of age for our pediatric population. Clinically, intellectual disability (ID), axial hypotonia and spastic paraparesis stood out in 4/4 and cerebellar symptoms in 2/4. Other manifestations were urinary incontinence, sensory-motor polyneuropathy, and behavioral alteration. In case 2, the alteration in the video-EEG stands out, which showed focal epilepsy with secondary generalization and right posterior occipito-parietal paroxysmal focality with contralateral transmission. She also showed instantaneous pluricotidian supraversion oculogyric seizures without EEG correlates., Conclusions: In our series, KAND encephalopathy had a predominant neurodegenerative disorder phenotype with global developmental delay, gait delay, and progressive spasticity of the lower limbs, cerebellar atrophy, and/or involvement of the visual cortex, which in one case was associated with sensory-motor polyneuropathy. The de novo missense mutation was more frequent and in three cases it is the first known description. One case showed focal epilepsy and nonepileptic oculogyric seizures.

Introduction: The aim of the study was to assess the use of faecal calprotectin (FCP) in infants with signs and symptoms of non-IgE-mediated cow's milk protein allergy (CMA) for both diagnosis and prediction of clinical response at the time of withdrawal of milk proteins., Patients and Methods: A one year prospective study was conducted on 82 infants between 1 and 12 months of age in the Eastern area of Málaga-Axarquía, of whom 40 of them had been diagnosed with non-IgE-mediated CMA (with suggestive symptoms and positive response to milk withdrawal), 12 not diagnosed with CMA, and 30 of them were the control group. FCP was measured at three different times: time of diagnosis, and one and three months later. ANOVA for repeated measures, nominal logistic regression and ROC curves were prepared using the SPSS.20 package and Medcalc., Results: Differences between diagnostic and control groups were assessed: there was a statistically significant relationship (p<.0001) between high FCP levels and infants suffering CMA, as well as the levels at time of diagnosis, 1 and 3 months (p <.001). A ROC curve was constructed between FCP levels and diagnosis of CMA, with 138 ug/g, with the best cut-off being with an area under the curve of 0.89. However, it is only 0.68 to predict a clinical response., Conclusions: FCP levels lower than 138ug/g could be useful to rule out non-IgE-mediated CMA diagnosis. Calprotectin is not a good test to predict clinical response to milk withdrawal., (Copyright © 2015 Asociación Española de Pediatría. Published by Elsevier España, S.L.U. All rights reserved.)

Clinical presentation of mitochondrial disorders is heterogeneous because the affected organs are those depending on a high rate of aerobic metabolism. They can appear at any age and evolution is progressive. Signs that guide diagnostic suspicion, especially in the pediatric age group, are heterogeneous clinical presentation and multisystem involvement. Within the spectrum of diseases caused by mitochondrial myopathy, there are clearly defined syndromes such as Kearns-Sayre syndrome. Muscle biopsy shows ragged red fibers and approximately 80 % of patients present sporadic deletions in mitochondrial DNA. Imaging studies reveal areas of hypointensity in basal ganglia and midbrain that are not visible after administration of contrast enhancement in computed tomography, and symmetric T2 hyperintensity lesions in these areas in magnetic resonance imaging. We present a patient with Kearns-Sayre syndrome, in whom radiological alterations were helpful in reaching the diagnosis.