Clinical, molecular, and pharmacological aspects of FMR1 related disorders. / Aspectos clínicos, moleculares y farmacológicos en los trastornos asociados a gen 1 del retraso mental del X frágil.

BACKGROUND: Fragile X syndrome, the most common inherited cause of intellectual disability, is associated with a broad spectrum of disorders across different generations of a single family. This study reviews the clinical manifestations of fragile X-associated disorders as well as the spectrum of mutations of the fragile X mental retardation 1 gene (FMR1) and the neurobiology of the fragile X mental retardation protein (FMRP), and also provides an overview of the potential therapeutic targets and genetic counselling. DEVELOPMENT: This disorder is caused by expansion of the CGG repeat (>200 repeats) in the 5 prime untranslated region of FMR1, resulting in a deficit or absence of FMRP. FMRP is an RNA-binding protein that regulates the translation of several genes that are important in synaptic plasticity and dendritic maturation. It is believed that CGG repeat expansions in the premutation range (55 to 200 repeats) elicit an increase in mRNA levels of FMR1, which may cause neuronal toxicity. These changes manifest clinically as developmental problems such as autism and learning disabilities as well as neurodegenerative diseases including fragile X-associated tremor/ataxia syndrome (FXTAS). CONCLUSIONS: Advances in identifying the molecular basis of fragile X syndrome may help us understand the causes of neuropsychiatric disorders, and they will probably contribute to development of new and specific treatments.

FXTAS in an unmethylated mosaic male with fragile X syndrome from Chile.

Carriers of an FMR1 premutation allele (55-200 CGG repeats) often develop the neurodegenerative disorders, fragile X-associated tremor/ataxia syndrome (FXTAS). Neurological signs of FXTAS, parkinsonism and rapid onset of cognitive decline have not been reported in individuals with an unmethylated full mutation (FM). Here, we report a Chilean family affected with FXS, inherited from a parent carrier of an FMR1 unmethylated full mosaic allele, who presented with a fast progressing FXTAS. This case suggests that the definition of FXTAS may need to be broadened to not only include those with a premutation but also those with an expanded allele in FM range with a lack of methylation leading to elevated FMR1-mRNA expression levels and subsequent RNA toxicity.

Demencia semántica: presentación de dos casos y revisión de la literatura / Semantic dementia: report of two cases

Frontotemporal dementia is a neurodegenerative condition that presents with a number of distinct behavioral phenotypes. One of them is semantic dementia (SD), where exists a profound impairment for semantic knowledge related to atrophy of temporal poles. Pathologically, in most cases positive intraneuronal ubiquitin and tau negative inclusions are observed. SD is characterized by fluent, effortless, grammatical speech which lacks informational content, with limited and repetitive content, as well as semantic paraphasias. Also, patients may present with associative visual agnosia, surface dyslexia or dysgraphia, behavioral alterations. Both episodic and autobiographical memory are close to normality. Two female patients with fluent progressive aphasia are reported; they failed in a simple test of semantic association (to point to one of four objects with lesser relation to others). Autobiographical memory was fair. SD can be wrongly diagnosed as left-sided variant of Alzheimer's disease; absence of episodic amnesia and parietal defects may be useful for clinical diagnosis.

La demencia semántica es una variante de las atrofias lobares frontotemporales que se caracteriza por la degradación del conocimiento semántico, de los conceptos. En ella existe una atrofia predominante de los polos temporales, a veces asimétrica; la patología generalmente muestra neuronas con inclusiones ubiquitina (+) y tau (-). Se expresa como una afasia progresiva fluente, sin disartria ni agramatismo, con anomia y parafasias verbales o semánticas, poco informativa. Pueden existir agnosia visual asociativa y alteraciones conductuales; a veces existen alexia y/o agrafía de superficie. Hay respeto relativo de la memoria episódica y autobiográfica. Se presentan dos mujeres con afasia progresiva fluente, alteraciones conductuales y falla en una tarea semántica (4º excluido). A pesar de estos defectos la memoria autobiográfica y el desempeño en sus actividades cotidianas estaban dentro de lo normal. Se concluye que estos cuadros deben diferenciarse de los casos de enfermedad de Alzheimer de predominio izquierdo; el respeto de la memoria episódica y la falta de compromiso parietal descartarían clínicamente esta última patología.

Estado actual de la terapia antiangiogénica en el manejo de gliomas de alto grado / Present state of the antiangiogenic therapy in the management of gliomas of high degree

High grade gliomas are lethal cancers. Despite recent advances in surgery, radiotherapy and chemotherapy, the overall survival is 15 months for glioblastoma. They are among the most vascular of human tumors, making them especially attractive targets for angiogenesis inhibitors. Most clinical trials of these agents as monotherapy have failed to demonstrate survival benefit in unselected high grade glioma patient populations. Several mechanisms of treatment failure have been postulated. In response, there are new intervention strategies on course: the combination of target therapy with classic chemotherapy, multitargeted kinase inhibitors and combinations of single-targeted kinase inhibitors and the identification of correlative biomarkers. These advances provide real opportunities for the development of effective therapies for high grade gliomas.