Clinical, Biochemical and Molecular Characterization of a Cohort of Glycogen Storage Disease Type I Patients in a High Complexity Hospital in Argentina

Abstract Glycogen storage disease type I is an autosomal recessive disorder of carbohydrate metabolism that manifests mainly by hepatomegaly and hypoglycemia with short fasts. Despite strict therapy, patients present long-term renal and liver complications. Data of 36 patients,29 GSD Ia and 7 Ib from a high complexity Hospital in Argentina was collected retrospectively. Collected data included diagnosis, anthropometric, biochemical parameters, therapy and follow-up. Treatment increased Height SDS (p=0.012). Patients with good adherence to therapy presented better growth parameters (p=0.049). Instead, admissions were detrimental (p =0.031) and were more common in Ib patients (p=0.002). The early appearance of complications (liver adenomas and nephropathy) was related to sustained triglyceride values > 500mg / dl (p=0.009 and 0.046 respectively). With intensive dietary treatment, clinical and biochemical status improves but cannot be completely corrected in most patients. Growth improves with treatment and this is optimized with adequate adherence. We must take into account that with ageing, more complications will develop.

Mitochondrial stress triggers a pro-survival response through epigenetic modifications of nuclear DNA.

Mitochondrial dysfunction represents an important cellular stressor and when intense and persistent cells must unleash an adaptive response to prevent their extinction. Furthermore, mitochondria can induce nuclear transcriptional changes and DNA methylation can modulate cellular responses to stress. We hypothesized that mitochondrial dysfunction could trigger an epigenetically mediated adaptive response through a distinct DNA methylation patterning. We studied cellular stress responses (i.e., apoptosis and autophagy) in mitochondrial dysfunction models. In addition, we explored nuclear DNA methylation in response to this stressor and its relevance in cell survival. Experiments in cultured human myoblasts revealed that intense mitochondrial dysfunction triggered a methylation-dependent pro-survival response. Assays done on mitochondrial disease patient tissues showed increased autophagy and enhanced DNA methylation of tumor suppressor genes and pathways involved in cell survival regulation. In conclusion, mitochondrial dysfunction leads to a "pro-survival" adaptive state that seems to be triggered by the differential methylation of nuclear genes.

Mitochondrial DNA deletions detected by Multiplex Ligation-dependent Probe Amplification.

The genetic diagnosis algorithm for mitochondrial (mt) diseases starts looking for deletions and common mutations in mtDNA. MtDNA's special features, such as large and variable genome copies, heteroplasmy, polymorphisms, and its duplication in the nuclear genome as pseudogenes (NUMTs), make it vulnerable to diagnostic misleading interpretations. Multiplex Ligation-dependent Probe Amplification (MLPA) is used to detect copy number variations in nuclear genes and its application on mtDNA has not been widely spread. We report three Kearns Sayre Syndrome patients and one Chronic Progressive External Ophthalmoplegia adult, whose diagnostic mtDNA deletions were detected by MLPA using a very low amount of DNA. This managed to "dilute" the NUMT interference as well as enhance MLPA's efficiency. By this report, we conclude that when MLPA is performed upon a reduced amount of DNA, it can detect effectively mtDNA deletions. We propose MLPA as a possible first step method in the diagnosis of mt diseases.

[The importance of a law on time: presentation of a girl with biotinidase deficiency who was not picked up through the neonatal screening]. / La importancia de una ley a tiempo: presentación de un caso de deficiencia de biotinidasa no diagnosticado por pesquisa neonatal.

In August 2008, the province of Buenos Aires had not adhered to the National law number 26279, that establishes the obligatory nature of the neonatal screening for biotinidase deficiency, among other diseases. In that date, a girl was born in Buenos Aires. She was admitted in the Hospital "J. P. Garrahan" with lethargy, metabolic acidosis, hiperlactacidemia, alopecia, conjuntivitis and scaly erythematous eruption in trunk, at 58 days of life, from a pediatric intensive care unit. Due to this clinic (13 days of evolution), a biotinidase assay in serum was done. This was abnormally low. She initiates treatment with biotin and the biochemical abnormalities revert quickly. If the neonatal screening had been done, this girl wouldn't have been exposed at risk of death, and a normal development would have been assure (by the presymptomatic beginning of the treatment), since the neurological injuries not always go back ad integrum.

La importancia de una ley a tiempo: Presentación de un caso de deficiencia de biotinidasa no diagnosticado por pesquisa neonatal / The importance of a law on time: presentation of a girl with biotinidase deficiency who was not picked up through the neonatal screening

En agosto de 2008, la Provincia de Buenos Aires no había adherido a la Ley Nacional 26279, que establece la obligatoriedad de la pesquisa neonatal para la deficiencia de biotinidasa, entre otras enfermedades. En esa fecha, nace en la Provinciade Buenos Aires una niña que derivan desde una terapia intensiva pediátrica al Hospital Nacional de Pediatría Dr. Prof. J. P. Garrahan, a los 58 días de vida, por alteración del sensorio, acidosis metabólica, hiperlacticoacidemia, alopecia, conjuntivitis y erupción cutánea eritematosa escaldada. Por estaclínica (de 13 días de evolución) se mide la actividad plasmática de biotinidasa, que resultó baja. Se inicia tratamiento con biotina y revierten rápidamente las alteraciones bioquímicas que presentaba. Si se hubiera hecho la pesquisa neonatal, estaniña no hubiera estado expuesta a riesgo de muerte por la enfermedad y se hubiese asegurado (por el inicio presintomático del tratamiento), un desarrollo normal, ya que las lesiones neurológicas no siempre retrogradan o no lo hacen ad integrum.