RESUMEN
Fatal cerebral hemorrhage involving the left thalamus in a neonate was attributed to deep cerebral vein thrombosis. Although antithrombin levels were at the lower end of the normal range, family and genetic studies showed constitutional type I antithrombin deficiency related to a novel missense mutation in the antithrombin gene.
Asunto(s)
Antitrombinas/deficiencia , Hemorragia Cerebral/genética , Mutación Puntual , Antitrombinas/genética , Resultado Fatal , Humanos , Recién Nacido , Masculino , Trombosis de la Vena/complicacionesRESUMEN
Why severe Plasmodium falciparum malaria occurs in only a small percentage of patients is unclear. The possibility that specific parasite characteristics contribute to severity has been investigated in French Guiana, a hypoendemic area, where parasite diversity is low and all patients with severe cases are referred to a single intensive care unit. Parasite genotyping in geographically and temporally matched patients with mild and severe disease showed that the association of a specific msp-1 allele (B-K1) with a specific var gene (var-D) was overrepresented among patients with severe versus mild disease (47% vs. 3%, respectively; P<.001). Moreover, this genotype combination was consistently observed in the most severe clinical cases. Reverse-transcription polymerase chain reaction demonstrated programmed expression of var-D in vivo, which is consistent with its potential implication in severe disease. These results provide field evidence of an association of severe malaria with specific genetic characteristics of parasites and open the way for intervention strategies targeting key virulence factors of parasites.
Asunto(s)
ADN Protozoario/análisis , Malaria Falciparum/diagnóstico , Malaria Falciparum/parasitología , Plasmodium falciparum/clasificación , Animales , Guyana Francesa/epidemiología , Genotipo , Humanos , Malaria Falciparum/etnología , Plasmodium falciparum/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Índice de Severidad de la EnfermedadRESUMEN
The genetic characteristics of Plasmodium falciparum isolates collected in French Guiana, where malaria transmission is low and occurs in isolated foci, were studied. Blood samples were collected from 142 patients with symptomatic malaria and typed using a polymerase chain reaction-based strategy for merozoite surface protein-(MSP-1) block 2, the MSP-2 central domain, and glutamate-rich protein (GLURP) repeat domain polymorphism. This showed that the parasite population circulating in French Guiana presented a limited number of allelic forms (4, 2, and 3 for MSP-1 block 2, MSP-1, and GLURP, respectively) and a small number of mixed infections, contrasting with the large genetic diversity of parasite populations and infection complexity reported for Africa, Asia, and other parts of South America. Two groups of isolates displaying identical 3 loci allele combinations were further studied for the Pf332 antigen, histidine-rich protein-1, thrombospondin-related anonymous protein, and Pf60 multigene family polymorphism. Within each group, most isolates were identical for all markers tested. This suggests a high rate of self-fertilization of P. falciparum parasites in French Guiana, resulting in homogenization of the population. The implications of these findings for malaria control in areas of low endemicity are discussed.