The TaqIA polymorphism linked to the DRD2 gene is related to lower attention and less inhibitory control in alcoholic patients.

The TaqIA polymorphism linked to the DRD2 gene has been associated with alcoholism. The aim of this work is to study attention and inhibitory control as per the continuous performance test and the stop task in a sample of 50 Spanish male alcoholic patients split into two groups according to the presence of the TaqIA1 allele in their genotype. Our results show that alcoholics carrying the TaqIA1 allele present lower sustained attention and less inhibitory control than those patients without such allele.

Depression in Parkinson's disease is related to a genetic polymorphism of the cannabinoid receptor gene (CNR1).

Depression is a common symptom in Parkinson's disease (PD) and it is present in up to 40% of the patients. The cause of depression in PD is thought to be related to disturbance of monoamine neurotransmission. The endogenous cannabinoid system mediates different brain processes that play a role in the control of behaviour and emotions. Cannabinoid function may be altered in neuropsychiatry diseases, directly or through interactions with monoamine, GABA and glutamate systems. For this reason, we have investigated whether there is a genetic risk factor for depression in PD linked to the polymorphisms of CB1 receptor gene. Depression was more frequent in patients with PD than in controls with osteoarthritis. The presence of depression did not correlate with the stage of the disease but it was more frequent in patients with pure akinetic syndrome than in those with tremoric or mixed type PD. The CB1 receptor gene polymorphism (AAT)n is considered to modify the transcription of the gene and, therefore, it may have functional relevance. We analysed the length of the polymorphic triplet (AAT)n of the gene that encodes CB1 (CNR1) receptor in 89 subjects (48 PD patients and 41 controls). In patients with PD, the presence of two long alleles, with more than 16 repeated AAT trinucleotides in the CNR1 gene, was associated with a reduced prevalence of depression (Fisher's exact test: P=0.003). This association did not reach significant differences in the control group, but the number of control individuals with depression was too small to allow for statistical analysis. Since the alleles with long expansions may have functional impact in cannabinoid neurotransmission, our data suggest that the pharmacological manipulation of cannabinoid neurotransmission could open a new therapeutic approach for the treatment of depression in PD and possibly in other conditions.

The A1 allele of the DRD2 gene (TaqI A polymorphisms) is associated with antisocial personality in a sample of alcohol-dependent patients.

BACKGROUND: Presence of A1 allele of the DRD2 gene has been associated with a predisposition for alcoholism although there are limited data about its phenotypic expression in alcoholism. OBJECTIVES: To determine the importance of the A1 allele in clinical variables of alcohol dependence. METHODOLOGY: A sample of 103 alcohol-dependent males was studied. All patients were recruited consecutively from the general hospital and community settings. The diagnostics were made with the structured clinical interview for DSM-III-R (SCID); and the International Personality Disorder Examination (IPDE). Diagnosis of family alcoholism was made by direct interview or with the Research Diagnostic Criteria-Family History (RDC-FH). The Addiction Severity Index (ASI) and the Severity of Alcohol Dependence Scale (SADS) were used to assess alcohol dependence severity. Genotyping was done by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) methods. RESULTS: Approximately 39% of the sample carried the A1 allele (A1+ group). This group had higher prevalences of antisocial personality disorder (60% vs. 15.9%); and alcoholism family history (72.5% vs. 52.4%). Also A1+ had early onset alcohol abuse and more drinking problems. The presence of A1+ was the main factor to explain the diagnosis of antisocial personality disorder, but the weight of this factor was not sufficient to explain the complications assessed by the ASI. CONCLUSIONS: Our results support the existence of an association between the A1 allele and factors resulting from dopaminergic deficiency, otherwise denominated reward deficiency syndrome.

Aspectos genéticos del alcoholismo / Genetic aspects of alcoholism

Objetivo: El alcoholismo es un conjunto heterogéneo de trastornos que comparten su relación con la ingesta de etanol. La importancia de los factores genéticos en el desarrollo del alcoholismo está avalada por una amplia serie de investigaciones llevadas a cabo desde hace años. Los estudios de familia, en gemelos y de adopción indican que los hijos de padres alcohólicos tienen un marcado riesgo para el trastorno. En la actualidad, el avance de las técnicas moleculares ha aportado un nuevo enfoque al estudio de la asociación entre genética y alcoholismo. Material y métodos: Se revisan los aspectos genéticos del alcoholismo. Resultados: Los efectos producidos por el alcohol, van a depender de la actividad de las enzimas encargadas de su degradación. Los individuos que presenten polimorfismos para alguno de sus genes, que impliquen una alteración en la eliminación del etanol, contribuirán a la variabilidad genética en su consumo y en sus efectos sobre el organismo. Por otro lado, sabemos que la capacidad adictiva del alcohol y otras drogas se basa en su capacidad para potenciar la transmisión dopaminérgica en el sistema mesolímbico, centro fundamental del sistema de recompensa, que se encuentra modulado por diferentes sistemas de neurotransmisores como el opioide y el serotoninérgico. La existencia de variantes genéticas para las proteínas clave de estos sistemas, podrán estar también relacionadas con su consumo. Conclusiones: El adecuado conocimiento de la importancia de los factores genéticos en el alcoholismo, y de su interrelación con otros factores fisiológicos y psicosociales, resulta fundamental para alcanzar un acercamiento más adecuado a los distintos trastornos relacionados con el alcohol para su correcta comprensión y manejo, y también para actuar, de forma preventiva, sobre los elementos que supongan un aumento en la vulnerabilidad a padecerlos. (AU)