The clinical and genetic spectrum of inherited glycosylphosphatidylinositol deficiency disorders

Inherited glycosylphosphatidylinositol deficiency disorders (IGDs) are a group of rare multisystem disorders arising from pathogenic variants in glycosylphosphatidylinositol anchor pathway (GPI-AP) genes. Despite associating 24 of at least 31 GPI-AP genes with human neurogenetic disease, prior reports are limited to single genes without consideration of the GPI-AP as a whole and with limited natural history data. In this multinational retrospective observational study, we systematically analyse the molecular spectrum, phenotypic characteristics, and natural history of 83 individuals from 75 unique families with IGDs, including 70 newly reported individuals: the largest single cohort to date. Core clinical features were developmental delay or intellectual disability (DD/ID, 90%), seizures (83%), hypotonia (72%), and motor symptoms (64%). Prognostic and biologically significant neuroimaging features included cerebral atrophy (75%), cerebellar atrophy (60%), callosal anomalies (57%), and symmetric restricted diffusion of the central tegmental tracts (60%). Sixty-one individuals had multisystem involvement including gastrointestinal (66%), cardiac (19%), and renal (14%) anomalies. Though dysmorphic features were appreciated in 82%, no single dysmorphic feature had a prevalence >30%, indicating substantial phenotypic heterogeneity. Follow-up data were available for all individuals, 15 of whom were deceased at the time of writing. Median age at seizure onset was 6 months. Individuals with variants in synthesis stage genes of the GPI-AP exhibited a significantly shorter time to seizure onset than individuals with variants in transamidase and remodelling stage genes of the GPI-AP (P=0.046). Forty individuals had intractable epilepsy. The majority of individuals experienced delayed or absent speech (95%); motor delay with non-ambulance (64%); and severe-to-profound DD/ID (59%). Individuals with a developmental epileptic encephalopathy (51%) were at greater risk of intractable epilepsy (P=0.003), non-ambulance (P=0.035), ongoing enteral feeds (P<0.001), and cortical visual impairment (P=0.007). Serial neuroimaging showed progressive cerebral volume loss in 87.5% and progressive cerebellar atrophy in 70.8%, indicating a neurodegenerative process. Genetic analyses identified 93 unique variants (106 total), including 22 novel variants. Exploratory analyses of genotype-phenotype correlations using unsupervised hierarchical clustering identified novel genotypic predictors of clinical phenotype and long-term outcome with meaningful implications for management. In summary, we expand both the mild and severe phenotypic extremities of the IGDs; provide insights into their neurological basis; and, vitally, enable meaningful genetic counselling for affected individuals and their families

Etude des rapports Fe3+/Fe2+ et OH-/F-, des éléments-traces dans les amphiboles des roches volcaniques des Petites Antilles ; estimation de fHF/fH2O

Study of separated amphiboles and biotites from calc-alkaline series of the Lesser Antilles permit to precise their crystal-chemistry : oxidation ratio of iron, trace element contents and to estimate the composition of fluid in equilibrium with them, fH2O/f HF ratio is about 106 in dacites.L'étude d'amphiboles et de micas séparés provenant des séries calco-alcalines de l'arc des Petites Antilles permet de préciser leur cristallochimie : degré d'oxydation du fer, éléments en trace notamment et d'estimer la composition de la phase fluide en équilibre avec ces minéraux : le rapport fH2O/f HF est voisin de 106 dans les dacites.D'Arco Philippe, Cotten Joseph. Etude des rapports Fe3+/Fe2+ et OH-/F-, des éléments-traces dans les amphiboles des roches volcaniques des Petites Antilles ; estimation de fHF/fH2O. In: Bulletin de Minéralogie, volume 108, 2, 1985. pp. 153-159

Modélisation ab initio périodique de quelques défauts azotés du diamant (contribution au code CRYSTAL)

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Le cœur alcalin du complexe du Messum, Namibie (description pétrologique, interprétation de l évolution minéralogique et relations roches sous- et sur-saturées en silice)

Le complexe anorogénique annulaire du Messum, associé à la province basaltique de l Etendeka (Namibie), montre la coexistence de roches sous- et sur-saturées en silice. Une étude pétrologique détaillée est nécessaire pour comprendre l évolution minéralogique de ces deux ensembles de roches. Dans le premier, l ensemble des observations a permis de proposer une route de cristallisation mettant en jeu des lignes (ou surfaces) péritectiques et expliquant le développement de la néphéline tardivement aux dépens des phases précoces (olivine, plagioclase, clinopyroxène alumineux) et la signification intermédiaire de la pargasite. Des minéraux significatifs non encore signalés sont décrits : spinelles dans les roches basiques, wohlérite et hiortdahlite dans les syénites les plus évoluées, ainsi que des pyrochlores considérés comme des indices potentiels de la présence de matériaux à affinités carbonatitique. Les syénites à quartz apparaissent comme un ensemble composite avec plusieurs venues différemment évoluées. Les paragenèses sont plus ou moins peralcalines, avec fayalite, hédenbergite acmitique, et développement tardif de riebéckite. La chevkinite, titano-silicate rare, y est décrit en quantité relativement abondante comme un minéral magmatique. Aucun lien minéralogique entre ces deux ensembles ne peut être établi ce qui rend peut crédible l hypothèse du passage de l un à l autre par contamination crustale.PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Sci.Terre recherche (751052114) / SudocSudocFranceF

Phase transitions and superexchange mechanism in transition metal compounds. The case of KMnF 3 perovskite

International audienceMany space groups are proposed in the literature for the KMnF3 perovskite (see, for example, Knight et al., J. Alloys Compd., 2020, 842, 155935), ranging from cubic (C) (Pm[3 with combining macron]m) to tetragonal (T) (Image ID:d1cp03816h-t1.gif or I4/m) down to orthorhombic (O) (Pbnm). The relative stability ΔE of these phases, both ferromagnetic (FM) and antiferromagnetic (AFM), has been investigated quantum mechanically by using both the B3LYP hybrid functional and the Hartree–Fock Hamiltonian, an all-electron Gaussian type basis set and the CRYSTAL code. The O phase is slightly more stable than the T phase which in turn is more stable than the C phase, in agreement with experimental evidence. The C to T to O transition is accompanied by a volume reduction. The mechanism of stabilization of the AFM solution with respect to the FM one is discussed. Spin density maps and profiles, Mulliken charges, magnetic moments and bond population data are used for supporting the proposed mechanism. The IR and Raman spectra of the FM and AFM C, T and O cells are discussed; the only noticeable difference between the C, T and O spectra appears at wavenumbers lower than 150 cm−1. The effect of pressure is also explored in the 0–20 GPa interval. The stability order (O > T > C) at 0 GPa persists also at high pressure, and the differences between the phases increase

Crystal chemistry and partitioning of halogens in hydrous silicates

International audienceUnderstanding how halogens are distributed among usual hydrous silicates in the lithosphere is important to constrain their deep geochemical cycle and fluid-rock interactions in subduction zones. This article presents firstprinciples modelling of halogen (F-, Cl-, Br-) incorporation in hydrous silicates including mica, chlorite, serpentine, amphibole, epidote and carpholite. The approach allows studying the impact of crystal chemistry on halogen partitioning by quantification of the energetic cost of halogen incorporation in minerals. Calculations are carried out in large systems where halogens are in minor to trace concentrations. Estimations show that F-bearing defects must be separated at least 9 Å from one another to reproduce trace element behaviour, this value increasing to at least 10 Å for Cl and Br. Results highlight the competition between the effects of electrostatic interactions and steric hindrance for incorporation of halogens, where steric hindrance has greater importance for heavy halogens, in particular for Br. Interaction with alkalis is a major control for F incorporation, especially in mica. Other parameters such as octahedral site occupancy, Si/Al ratio of tetrahedral sites and the nature of alkalis in amphibole and mica (K or Na) appear to play subordinate roles. Partition coefficients have been estimated in mineral assemblages in an effort to be representative of subduction zone metamorphism. Results show that pargasite, biotite and lizardite are favoured hosts for all three halogens, followed by clinochlore, tremolite and carpholite. The energetic cost of incorporating halogens into dioctahedral phyllosilicates and epidote is comparatively higher, and partitioning is predicted as unfavourable to these minerals. Fractionation between halogens in subduction zones is predicted by the evolution of mineral assemblages and partition coefficients, a consequence of the influence of crystal chemistry over halogen incorporation in hydrous silicates

Combinatorics meets potential theory

International audienc

Etude théorique des grenats silicatés et calcul des fréquences de vibrations dans les solides

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Sci.Terre recherche (751052114) / SudocFONTAINEBLEAU-MINES ParisTech (771862302) / SudocSudocFranceF

Jahn‐Teller distortion, octahedra rotations and orbital ordering in perovskites: KScF3 as a model system

International audienceAbstract The KScF perovskite has been used as a model for investigating the relative importance of the Jahn‐Teller (JT) lift of degeneracy, the ScF octahedra rotation (OR), and the quadrupole‐quadrupole interaction linked to different occupancy of the Sc t subshell in various sites of the unit cell (orbital ordering, OO). The group‐subgroup sequence , , , and , supplemented by and , has been explored by using an Gaussian type basis set, hybrid functionals, and the CRYSTAL17 code. The JT lift of degeneracy provides a stabilization about 5 times larger than the sum of the OO and OR effects. The energy gained in the transition from to , consisting in a rotation of the octahedra around the axis, is 1077 E. From to , additional rotations around the and axes are possible, and the Sc electron can occupy a different t orbital, with a total energy reduction of 2318 E. The rotation of the octahedra reduces the strength of superexchange: in going from to the G‐AFM stabilization with respect to FM shrinks by a factor 4

t2gd orbital ordering patterns in KBF3 (B = Sc, Ti, Fe, Co) perovskites

International audienceThe orbital ordering (OO) resulting from the partial occupancy of the subshell of the transition metals in KBF (B = Sc, Ti, Ffe, Co) perovskites, and the many possible patterns arising from the coupling between the B sites, have been investigated at the quantum mechanical level ( Gaussian type basis set, B3LYP hybrid functional) in a 40 atoms supercell. The numerous patterns are distributed into 162 classes of equivalent configurations. For each fluoroperovskite, one representative per class has been calculated. The four compounds behave similarly: an identical dependence of the energy and volume (or cell parameters) on the OO pattern; the spanned energy interval is small (1 to 2 mE per formula unit), suggesting that most of the configurations are occupied at room and even at low temperature. A linear model, taking into account the relative orbital order in contiguous sites, reproduces the energy order in the full set for each compound, suggesting that it could be used for studying OO in larger supercells