Eight further individuals with intellectual disability and epilepsy carrying bi-allelic CNTNAP2 aberrations allow delineation of the mutational and phenotypic spectrum

Background Heterozygous copy number variants (CNVs) or sequence variants in the contactin-associated protein 2 gene CNTNAP2 have been discussed as risk factors for a wide spectrum of neurodevelopmental and neuropsychiatric disorders. Bi-allelic aberrations in this gene are causative for an autosomal-recessive disorder with epilepsy, severe intellectual disability (ID) and cortical dysplasia (CDFES). As the number of reported individuals is still limited, we aimed at a further characterisation of the full mutational and clinical spectrum. Methods Targeted sequencing, chromosomal microarray analysis or multigene panel sequencing was performed in individuals with severe ID and epilepsy. Results We identified homozygous mutations, compound heterozygous CNVs or CNVs and mutations in CNTNAP2 in eight individuals from six unrelated families. All aberrations were inherited from healthy, heterozygous parents and are predicted to be deleterious for protein function. Epilepsy occurred in all affected individuals with onset in the first 3.5 years of life. Further common aspects were ID (severe in 6/8), regression of speech development (5/8) and behavioural anomalies (7/8). Interestingly, cognitive impairment in one of two affected brothers was, in comparison, relatively mild with good speech and simple writing abilities. Cortical dysplasia that was previously reported in CDFES was not present in MRIs of six individuals and only suspected in one. Conclusions By identifying novel homozygous or compound heterozygous, deleterious CNVs and mutations in eight individuals from six unrelated families with moderate-to-severe ID, early onset epilepsy and behavioural anomalies, we considerably broaden the mutational and clinical spectrum associated with bi-allelic aberrations in CNTNAP2

Synthèse des minéralocorticoïdes, mastocytes surrénaliens et adaptation à la vie extra-utérine

International audienceChez le nouveau-né, l’aldostéronémie élevée, indépendante des valeurs maternelles fait évoquer une régulation autonome de la synthèse des minéralocorticoïdes. Chez l’adulte, les mastocytes intrasurrénaliens régulent de façon paracrine la synthèse d’aldostérone via la sécrétion de sérotonine. Récemment chez le fœtus, la présence de mastocytes intrasurrénaliens dès 20 semaines d’aménorrhée (SA) suggère l’existence d’un mécanisme similaire. Le but de notre étude était : (i) d’analyser la densité mastocytaire ; (ii) d’étudier l’expression des enzymes de la voie de synthèse des minéralocorticoïdes et des protéines de la voie de signalisation sérotoninergique, dans la glande surrénale en période fœtale et néonatale selon le terme et les conditions de naissance. Nous avons réalisé une étude immunohistochimique sur des tissus fœtaux (n =17) et néonataux (n =7) humains entre 23 et 41 SA. Un comptage des cellules tryptase-immunopositives (mastocytes) a été effectué dans la zone 3β-hydroxystéroïde déshydrogénase de type 2 (3β-HSD2) positive. Une expression des enzymes 3β-HSD2 et aldostérone synthase (CYP11B2) plus intense ainsi qu’une densité mastocytaire plus élevée sont observées chez les nouveau-nés comparés aux fœtus entre 28 SA et 32 SA. Les mastocytes sont détectés au voisinage des cellules immunopositives pour la tryptophane hydroxylase de type 1, le récepteur sérotoninergique de type 4, la 3β-HSD2 et CYP11B2. Enfin, la densité mastocytaire apparaît plus élevée en cas d’hypoxie anténatale. Collectivement, ces résultats suggèrent un contrôle de la synthèse d’aldostérone néonatale par les mastocytes dans l’adaptation à la vie extra-utérine, notamment en cas de grande prématurité, via la voie de signalisation sérotoninergique

Eight further individuals with intellectual disability and epilepsy carrying bi-allelicCNTNAP2aberrations allow delineation of the mutational and phenotypic spectrum

BACKGROUND : Heterozygous copy number variants (CNVs) or sequence variants in the contactin-associated protein 2 gene CNTNAP2 have been discussed as risk factors for a wide spectrum of neurodevelopmental and neuropsychiatric disorders. Bi-allelic aberrations in this gene are causative for an autosomal-recessive disorder with epilepsy, severe intellectual disability (ID) and cortical dysplasia (CDFES). As the number of reported individuals is still limited, we aimed at a further characterisation of the full mutational and clinical spectrum. METHODS: Targeted sequencing, chromosomal microarray analysis or multigene panel sequencing was performed in individuals with severe ID and epilepsy. RESULTS: We identified homozygous mutations, compound heterozygous CNVs or CNVs and mutations in CNTNAP2 in eight individuals from six unrelated families. All aberrations were inherited from healthy, heterozygous parents and are predicted to be deleterious for protein function. Epilepsy occurred in all affected individuals with onset in the first 3.5 years of life. Further common aspects were ID (severe in 6/8), regression of speech development (5/8) and behavioural anomalies (7/8). Interestingly, cognitive impairment in one of two affected brothers was, in comparison, relatively mild with good speech and simple writing abilities. Cortical dysplasia that was previously reported in CDFES was not present in MRIs of six individuals and only suspected in one. CONCLUSIONS: By identifying novel homozygous or compound heterozygous, deleterious CNVs and mutations in eight individuals from six unrelated families with moderate-to-severe ID, early onset epilepsy and behavioural anomalies, we considerably broaden the mutational and clinical spectrum associated with bi-allelic aberrations in CNTNAP2

Respiration resolved imaging with continuous stable state 2D acquisition using linear frequency SWEEP

Purpose To investigate the potential of continuous radiofrequency (RF) shifting (SWEEP) as a technique for creating densely sampled data while maintaining a stable signal state for dynamic imaging. Methods We present a method where a continuous stable state of magnetization is swept smoothly across the anatomy of interest, creating an efficient approach to dense multiple 2D slice imaging. This is achieved by introducing a linear frequency offset to successive RF pulses shifting the excited slice by a fraction of the slice thickness with each successive repeat times (TR). Simulations and in vivo imaging were performed to assess how this affects the measured signal. Free breathing, respiration resolved 4D volumes in fetal/placental imaging is explored as potential application of this method. Results The SWEEP method maintained a stable signal state over a full acquisition reducing artifacts from unstable magnetization. Simulations demonstrated that the effects of SWEEP on slice profiles was of the same order as that produced by physiological motion observed with conventional methods. Respiration resolved 4D data acquired with this method shows reduced respiration artifacts and resilience to non-rigid and non-cyclic motion. Conclusions The SWEEP method is presented as a technique for improved acquisition efficiency of densely sampled short-TR 2D sequences. Using conventional slice excitation the number of RF pulses required to enter a true steady state is excessively high when using short-TR 2D acquisitions, SWEEP circumvents this limitation by creating a stable signal state that is preserved between slices

Molecular Characterization of a Class I P450 Electron Transfer System from Novosphingobium aromaticivorans DSM12444*

Cytochrome P450 (CYP) enzymes of the CYP101 and CYP111 families from the oligotrophic bacterium Novosphingobium aromaticivorans DSM12444 are heme monooxygenases that receive electrons from NADH via Arx, a [2Fe-2S] ferredoxin, and ArR, a ferredoxin reductase. These systems show fast NADH turnovers (kcat = 39–91 s−1) that are efficiently coupled to product formation. The three-dimensional structures of ArR, Arx, and CYP101D1, which form a physiological class I P450 electron transfer chain, have been resolved by x-ray crystallography. The general structural features of these proteins are similar to their counterparts in other class I systems such as putidaredoxin reductase (PdR), putidaredoxin (Pdx), and CYP101A1 of the camphor hydroxylase system from Pseudomonas putida, and adrenodoxin (Adx) of the mitochondrial steroidogenic CYP11 and CYP24A1 systems. However, significant differences in the proposed protein-protein interaction surfaces of the ferredoxin reductase, ferredoxin, and P450 enzyme are found. There are regions of positive charge on the likely interaction face of ArR and CYP101D1 and a corresponding negatively charged area on the surface of Arx. The [2Fe-2S] cluster binding loop in Arx also has a neutral, hydrophobic patch on the surface. These surface characteristics are more in common with those of Adx than Pdx. The observed structural features are consistent with the ionic strength dependence of the activity

Assessment of Digital PCR as a Primary Reference Measurement Procedure to Support Advances in Precision Medicine

Genetic testing for point mutations guides patient management in many cancers when analysing the DNA from tumour and, increasingly, liquid biopsies. Such measurements are going to be increasingly important in supporting the implementation of precision medicine that many predict will revolutionise clinical care. However, there are currently no reference measurement procedures available to aid harmonisation of existing testing and support implementation of newer, often more complex, tests into routine use. This study assessed the accuracy of digital PCR for copy number quantification of point mutations by evaluating potential sources of uncertainty influencing measurements of a frequently occurring mutation in colorectal cancer (KRAS G12D). Concentration values for samples containing single or mixed KRAS G12D and WT plasmid templates varied by <1.2-fold and <1.3-fold when measured using five assays differing in chemistry or with five commercial dPCR platforms. Orthogonal comparison with a chemical method (ICP-MS) via P quantification also demonstrated 1.2-fold agreement between techniques. dPCR showed robust quantification for templates of differing fragment sizes (186 – 4343 bp) and high intra- and inter-laboratory precision (%CV: 2-8% and 5-10% respectively). This work supports dPCR being more widely accepted as a SI traceable reference measurement procedure for value assignment of DNA reference materials of varying sizes in an aqueous (calibration) solution for copy-number concentration and allelic frequency measurements. Such high accuracy measurements using dPCR will be able to support the implementation and harmonisation of the molecular diagnostic procedures such as those needed to support the predicted advances in precision and personalised medicine.JRC.F.6-Reference Material