Twin Studies and Their Implications for Molecular Genetic Studies: Endophenotypes Integrate Quantitative and Molecular Genetics in ADHD Research

Explain the usefulness of dual studies in attention deficit / hyperactivity disorder (ADHD) studies and used them to identify alternative phenotypes suitable for genome-wide association, development risk assessment, therapeutic response, and intervention goals Demonstrate what you can do

A brief description of classical twin studies and genetically related research methods, as well as illustrative findings from ADHD studies are provided. Biostatistics refers to the statistical modeling of data gathered from one or more sets of known biological relationships, which clearly was created by Francis Galton in the 1860's to the University of London's "Biostatistics School" . Twin studies use this theoretical framework to derive genetic correlations between relatives that break down individual differences in characteristics into potential (unmeasured) genetic and environmental influences. This method can estimate the heritability, the proportion of variance caused by genetic influences. This is usually implemented in a way called structure modeling. This is usually a statistical technique used to fit the model to the data using maximum likelihood estimation. Genetic association research is aimed at identifying genetic genetic mutations that are presumed by twin studies. Measurements other than measurements for clinically diagnosed diseases are common phenotypic choices in current ADHD studies. Twin studies are believed to have great potential to improve the phenotype associated with ADHD.

Previous studies have consistently discovered that most of the changes in ADHD symptoms are caused by genetic factors. To date, ADHD genome-wide association analysis has not identified a reproducible association of interpretable genetic mutations. Probably applying the genome-wide association analysis to these alternative phenotypic measurements will help to identify pathways from genetic variation to ADHD

The ability to detect relevance can be improved by studying highly inherited phenotypes within ADHD and reducing the number of phenotypes to examine. Therefore, twin studies are an important research tool for the development of internal phenotypes, defined as an alternative, more heritable trait that plays a role in the early stages of gene-to-action pathways. Although the genetic variation of ADHD may be polygenic, the proposed method should help identify improved surrogate measurements for genetic association studies.

The amazing development of molecular genetics has influenced twin studies in many ways. First, progress in molecular genetics confirms the hypotheses created by traditional twin research designs. The importance of the genes proposed in early twin studies is often confirmed by later molecular genetics studies. For example, many twin studies have supported an important role of genetic factors in reading disorders and dyslexia. In general, twin studies attribute genetic factors to 40% to 70% of people's reading fluctuations. Recent molecular genetic studies have identified several chromosomal regions that may be associated with susceptibility

Genetic studies have just begun to identify genes associated with ADHD. In addition to molecular genetic research, the genetic component of this condition is supported by various family studies. For example, in one study, more than 25% of families with ADHD suffered from this disease and found that it is much higher than families without ADHD. Furthermore, in the twin studies, it is shown that when at least one pair of twins have ADHD, the same twin has a probability of 82%, and the odds of sibling twins are 38%. Finally, children of adopted ADHD are more likely to have ADHD in their biological homes than adoptive families. This confirms that genetic factors are much stronger than any environmental factors.

Molecular Genetics Study: Twin studies support the hypothesis that genes play an important role in triggering ADHD, but these studies did not identify specific genes associated with disease. Genetic research on ADHD has started in the past five years. The study focused on specific genes that may be involved in the spread of ADHD. Dopamine gene is the starting point for research. According to reports, many scientists believe that the two dopamine genes DAT1 and DRD4 are associated with ADHD. Genetic research has shown promising results, we should find more relevant information as soon as possible