[Heritability and genetic comorbidity of attention deficit disorder with hyperactivity].

This review aims to summarize information about the genetic etiology of attention deficit disorder with hyperactivity (ADHD), with particular reference to the contributions of our research group. We also discuss the genetic comorbidity estimated from genome-wide single nucleotide polymorphisms (SNP´s) between ADHD and major psychiatric disorders such as schizophrenia (E), major depressive disorder (MDD), bipolar disorder (BD) and autism spectrum disorders (ASD). A high genetic comorbidity was found between E and BD (46%), a moderate comorbidity between MDD and E, MDD and BD and MDD and ADHD (18%, 22% and 10% respectively) and a low comorbidity between E and ASD (2.

[Attention deficit hyperactivity disorder in Aymara children].

Background: The assessment of Attentional Deficit Hyperactivity Disorder (ADHD) among ethnic groups may reveal environmental or cultural variables that influence the appearance of this disorder.

Aim: To assess the presence and characteristics of ADHD in two communities of the inland Arica valleys (Azapa and Lluta), where the Aymara population predominates.

Material And Methods: Starting from a screening based on the Conner's test, we evaluated 79 children aged 8 to 13 years.

[DRD4 dopamine receptor alleles in Chilean students of different ethnic origin and its relation with the risk for attention deficit/hyperactivity disorder].

Background: Worldwide diversity of alleles of D4 receptor gene (DRD4), linked to attention deficit hyperactivity disorder (ADHD), is mostly the result of length and single nucleotide polymorphisms in a 48-bp tandem repeat (VNTR). Alleles containing from two (2R) to eleven (11R) repeats have been identified. The most common are 4R, 7R and 2R.

[Risk of attention deficit/hyperactivity disorder in Aymara and Rapa-Nui school children: association with dopaminergic system polymorphisms].

Background: Attention deficit/hyperactivity disorder (ADHD) is a common, highly heritable neurobiological disorder of childhood onset, characterized by hyperactivity, impulsiveness or inattentiveness.

Aim: To search for differences in risk for ADHD and its components among Chilean native and mixed populations and to look forpossible associations with dopamine receptor D4 (DRD4) and dopamine transporter 1 (DAT1) polymorphisms.

Material And Methods: School teachers were requested to complete the Conners test, which uses DSM-IV criteria, to screen for ADHD risk among Aymara and Rapa-Nui students.

Genotypic interaction between DRD4 and DAT1 loci is a high risk factor for attention-deficit/hyperactivity disorder in Chilean families.

Attention-deficit/hyperactivity disorder, ADHD [MIM 126452], is a common, highly heritable neurobiological disorder of childhood onset, characterized by hyperactivity, impulsiveness, and/or inattentiveness. As part of an ongoing study of ADHD, we carried out a family-based discordant sib-pair analysis to detect possible associations between dopamine receptor D4 (DRD4) and dopamine transporter 1 (DAT1) polymorphisms and ADHD in Chilean families. Both loci individually classified as homozygotes or heterozygotes for the DRD4 7-repeat and DAT1 10-repeat alleles, did not exhibit genotype frequency differences between affected children and their healthy siblings (Fisher's exact test P > 0.

Williams syndrome: pediatric, neurologic, and cognitive development.

This study examines the developmental history of 32 Williams syndrome patients, positive to the fluorescence in situ hybridization (FISH) test. The information is intended to provide help for early diagnosis and appropriate stimulation of these patients. In the sample reported here, only about half of the patients referred with presumptive diagnosis were in fact FISH+, indicating that facial dysmorphism may not be the most reliable sign for diagnosis.

[Presence of DRD4/7R and DAT1/10R allele in Chilean family members with attention deficit hyperactivity disorder].

Background: Genes for dopamine receptor DRD4 and dopamine transporter DAT1 have been implicated in attention deficit with hyperactivity disorder (ADHD). However, the findings are not conclusive. More studies in populations with different genetic backgrounds may contribute to solve the discrepancies observed.

Effect of psychostimulants on distinct attentional parameters in attentional deficit/hyperactivity disorder.

Although there is extensive literature about the effects of stimulants on sustained attention tasks in attentional deficit/hyperactivity disorder (ADHD), little is known about the effect of these drugs on other attentional tasks involving different neural systems. In this study we measured the effect of stimulants on ADHD children, both in the electroencephalographic (EEG) activity during sustained attentional tasks and in psychometric performance during selective attentional tasks. These tasks are known to rely on different cortical networks.