Congenital Disorders of Glycosylation (CDG) are scarcely reported from Latin America. We here report on a Mexican mestizo with a multi-systemic syndrome including neurological involvement and a type I transferrin (Tf) isoelectric focusing (IEF) pattern. Clinical exome sequencing (CES) showed known compound missense variants in
PMM2
c.422G > A (p.R141H) and c.395 T > C (p.I132T), coding for the phosphomanomutase 2 (PMM2). PMM2 catalyzes the conversion of mannose-6-P to mannose-1-P required for the synthesis of GDP-Man and Dol-P-Man, donor substrates for glycosylation reactions. This is the third reported Mexican CDG patient and the first with PMM2-CDG.
PMM2
has been recently identified as one of the top 10 genes carrying pathogenic variants in a Mexican population cohort.
This study reports on a Mexican mestizo patient with a multi-systemic syndrome including neurological involvement and a type I serum transferrin profile. Clinical exome sequencing revealed complex alleles in ALG1, the encoding gene for the chitobiosyldiphosphodolichol beta-mannosyltransferase that participates in the formation of the dolichol-pyrophosphate-GlcNAc2Man5, a lipid-linked glycan intermediate during N-glycan synthesis. The identified complex alleles were NM_019109.5(ALG1): c.[208 + 16_208 + 19dup; 208 + 25G > T] and NM_019109.5(ALG1): c.[208 + 16_208 + 19dup; 1312C > T]. Although both alleles carried the benign variant c.208 + 16_208 + 19dup, one allele carried a known ALG1 pathogenic variant (c.1312C > T), while the other carried a new uncharacterized variant (c.208 + 25G > T) causing non-functional alternative splicing that, in conjunction with the benign variant, defines the pathogenic protein effect (p.N70S_S71ins9). The presence in the patient’s serum of the pathognomonic N-linked mannose-deprived tetrasaccharide marker for ALG1-CDG (Neu5Acα2,6Galβ1,4-GlcNAcβ1,4GlcNAc) further supported this diagnosis. This is the first report of an ALG1-CDG patient from Latin America.
A subgroup of congenital disorders of glycosylation (CDGs) includes inherited GPI-anchor deficiencies (IGDs) that affect the biosynthesis of glycosylphosphatidylinositol (GPI) anchors, including the first reaction catalyzed by the X-linked PIGA. Here, we show the first PIGA-CDG case reported in Mexico in a male child with a moderate-to-severe phenotype characterized by neurological and gastrointestinal symptoms, including megacolon. Exome sequencing identified the hemizygous variant PIGA c.145G>A (p.Val49Met), confirmed by Sanger sequencing and characterized as de novo. The pathogenicity of this variant was characterized by flow cytometry and complementation assays in PIGA knockout (KO) cells.
Las ciencias sociales, en su necesidad de recurrir a diferentes marcos teóricos y metodológicos, encuentran en el análisis del discurso una valiosa herramienta. Sin embargo, la recurrencia al análisis del discurso no es predominante, y quienes lo utilizan suelen ser analistas de ciertas disciplinas como la comunicación, la retórica o el resto de las ciencias del lenguaje. Los otros científicos sociales cuando practican el análisis del discurso suelen confundirlo, inconscientemente, como si se tratase de una hermenéutica; o bien, porque lo desconocen por completo, está fuera de sus recursos analíticos. Por esto, interesa en este artículo reflexionar la importancia y posibilidades epistemológicas y heurísticas del análisis del discurso, como elemento teóricometodológico en el desarrollo de las ciencias sociales
Los desórdenes congénitos de la glicosilación (CDG) son enfermedades poco frecuentes (EPOF) de tipo metabólico y hereditarias que ocurren como consecuencia de mutaciones en los genes que codifican para proteínas que participan, directa o indirectamente, en este proceso. La enfermedad clínicamente denominada Cutis Laxa Autosómica Recesiva tipo II-A (ARCL2A) es un tipo de CDG (ATP6V0A2-CDG) causado por mutaciones en ATP6V0A2, que codifica para la subunidad a2 del dominio v0 de una ATPasa vacuolar que tiene como función el transporte de iones H+ a través de las membranas celulares, regulando así el pH de los compartimentos celulares, e incluye la acidificación del aparato de Golgi. En 2014, nuestro grupo de investigación reportó por primera vez en México, la existencia de dos pacientes con ATP6V0A2-CDG. En este trabajo, se estableció una metodología para identificar a los portadores de la mutación c.187 C>T en el ATP6V0A2 mediante PCR-ARMS.
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