A gene is a part of Deoxyribonucleic acid (DNA), which contains all the information required to analysis the defects and genetic problems that evolves in an organism. A gene is also the element of information that is transferred through transcription and translation. This paper discusses the transformation that happens in the cell either internal or external environment, that can lead to changes in gene expression.Most human and animal diseases are manifested through a mis-regulation of gene expression. The outputs of DNA Microarray are processed by computation tools to take out biological significance which may help to detect human disease. Computation tools include a variety of algorithms of data mining, pattern recognition and machine learning etc. Finding desired algorithm plays a major role in research to satisfy the requirements. Computational analysis on supervised, unsupervised and semi supervised classification are considered for survey.