Genetic variation and diseases: persuasive developmental disorders, depression and fetal alcoholic disease

Abstract

The Pervasive Developmental Disorders (PDD), or Autism Spectrum Disorder (ASD) constitute a group characterized by abnormal early occurrence and are manifested in the areas of communication development, behavior and interpersonal relationship. Several association studies with candidate genes suggest involvement of serotonin system genes. The serotonin transporter gene (5-HTT) has been examined in several different populations together. The function of serotonin is exerted through its interaction with specific receptors. In Brazil, two recent studies were performed. One group found evidence of lower transmission of two alleles of a receiver but are cautious to establish any causal relationship. The other study with similar methodology researched the association of polymorphisms of the serotonin transporter gene in patients with PDD, suggesting the absence of a positive association between the alleles studied and Brazilian patients.Several studies have suggested that BDNF plays a fundamental role in the so-called 'neurotrophic hypothesis of depression. "According to this theory, the antidepressant treatment would have a "final common pathway" with increased expression of BDNF, restoration of neuroplasticity in the critical areas and, ultimately, reversal of the antidepressant. Two meta-analysis synthesized the findings of some 20 clinical studies demonstrating that there is an increase of about 30% in serum BDNF levels after various forms of antidepressant treatment. The Val66Met polymorphism seems to be a predictor of the perpetrator and Major Depressive Disorder and the determination of this BDNF polymorphism are interesting in our clinical trial in which depressed patients will undergo treatment with sertraline or transcranial direct current stimulation (tDCS)After the systematization of Fetal Alcohol Syndrome, several studies were conducted to assess the real health risks caused by maternal-fetal use and abuse of alcohol during pregnancy. The influence of polymorphisms in loci encoding the enzyme alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) in the risk of developing alcohol dependence is well characterized in some populations but not in Brazil. (AU)