Functional genomics is an area of ​​study in molecular biology that attempts to analyze gene products, in order to understand the function and interaction of genes and proteins produced by them. It is a method that analyzes the entire genome used in different environmental conditions, and the function of DNA can be deciphered through a combination of genes, proteins and transcripts. The new approach provides geneticists with possible answers to understand how genes interact with each other and analyze DNA sequences of organisms that are unique to biological systems. Genomics is undergoing rapid development from the analysis, mapping and sequencing of genomes to the development of genome function. [Hieter and Boguski, 1997] Genomics looks at the analysis of DNA sequences while functional genomics is used to understand the relationship between genes and proteins. [Fields et al., 1999] Genome analysis has more recently been divided into two groups; Functional and structural genomics. Structural genomics is the first phase of genome analysis, which produces the genetic, transcriptional, and physical maps of an organism. [Hieter and Boguski, 1997] The aim of structural genomics is the assignment of three-dimensional structures to proteomes; which provided a new perspective on protein families and folds and domain structures within genetic sequences. [Teichmann et al., 1999] Functional genomics requires genome-wide experimental approaches that can understand the behavior of biological systems simultaneously and analyze multiple genes and proteins of an organism simultaneously. The expanding field of functional genomics promises to “narrow the gap between sequences and functions while developing new insights into biological systems.” [Hieter and B...... half of article ......g were developed, however DNA microarray has enabled research into axon guidance pathways, allowing scientists to analyze change in proteins ​of the pathways that lead to the disease. Furthermore, the analysis of the α-synuclein gene, the ALDH1A1 gene and the SEMA5A gene shows the possibility of conclusive data on which genes are affected and which genes cause an affect and lead to the symptoms of Parkinson's disease. However there are always limitations, which have become more apparent with research into neurological diseases, since human or animal cell tissue is always needed and the most challenging area is obtaining the accurate cell tissue from the diseased location of the brain. [Mandel et al., 2003]However, functional genomics is a research area that has been largely developed thanks to microarray technology; providing a large-scale platform for gene analysis.