Functional genomics is a field of study of molecular biology that attempts to analyze gene products, in order to understand the function and interaction of genes, as well as proteins produced by them. It is a genome-wide method 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 the DNA sequences of organisms that are unique to biological systems. Genomics is experiencing rapid development from the analysis, mapping and sequencing of genomes to the development of genome function. [Hieter and Boguski, 1997] Genomics examines 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 goal of structural genomics is the assignment of three-dimensional structures to proteomes; which provided a new perspective on protein families and folds, as well as domain structures within genetic sequences. [Teichmann et al., 1999] Functional genomics requires genome-wide experimental approaches that will simultaneously understand the behavior of biological systems and simultaneously analyze multiple genes and proteins of an organism. The growing field of functional genomics promises to “close the gap between sequence and function while developing new insight into biological systems.” [Hieter and B...... middle of article ......g grew, but microarrays enabled research into axon guidance pathways, allowing scientists to analyze the change in protein pathways that lead to disease. Furthermore, analysis of the α-synuclein gene, the ALDH1A1 gene and the SEMA5A gene shows possibilities for conclusive data as to which genes are affected and which genes cause an effect and lead to the symptoms of Parkinson's disease. However, there are still limitations, which have become more evident in neurological disease research, as human or animal cellular tissue is still required, and the most challenging area is obtaining the cellular tissue. accurate from the diseased location of the brain. [Mandel et al., 2003] Nevertheless, functional genomics is a field of research that has largely developed thanks to DNA chip technology; provide a large-scale platform for gene analysis.