Mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency (mitochondrial HMG-CoA synthase deficiency or mHS deficiency, OMIM #605911) is an inborn error of metabolism that affects ketone body synthesis. Acute episodes include vomiting, lethargy, hepatomegaly, hypoglycemia and dicarboxylic aciduria. The diagnosis is difficult due to the relatively unspecific clinical and biochemical presentation, and fewer than 30 patients have been described. This work describes three new patients with mHS deficiency and two missense mutations c.334C>T (p.R112W) and c.430G>T (p.V144L) previously not reported. We developed a new method to express and measure the activity of the enzyme and in this work the study is extended to ten new missense variants including those of our patients. Enzymatic assays showed that three of the mutant proteins retained some but seven completely lacked activity. The identification of a patient homozygous for a mutation that retains 70% of enzyme activity opens the door to a new interpretation of the disease by demonstrating that a modest impairment of enzyme function can actually produce symptoms. This is also the first study employing molecular dynamics modelling of the enzyme mutations. We show that the correct maintenance of the dimerization surface is crucial for retaining the structure of the active center and therefore the activity of the enzyme.

ResumenEl neuroblastoma olfatorio (NBO) es un tumor maligno poco frecuente que se origina de las células neuroepiteliales olfativas. Su diagnóstico precoz es difícil debido a la poca especificidad de los síntomas que presentan los pacientes. Las pruebas de imagen juegan un papel importante en su diagnóstico y en la planificación quirúrgica, por lo que es importante que los radiólogos conozcan sus hallazgos y las diferentes clasificaciones que ayudarán a elegir el tratamiento más adecuado para cada tumor.

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El embarazo ectópico se define como la implantación del óvulo fecundado fuera de la cavidad uterina. Alrededor del 95% de los embarazos ectópicos se localizan en la trompa. Las formas no tubáricas, en concreto sobre la cicatriz de una cesárea, son una entidad muy poco frecuente cuyo diagnóstico y tratamiento precoz son imprescindibles para evitar complicaciones graves y preservar la fertilidad.