**5. Discussion**

All humans have variation in genetic material, even identical twins by the time of born, and this variation give us the uniqueness. We inherit our genes from our parents, so the members of the same family share majority of their genetic material involving its variations. The variation in DNA that cause wrong in required genetic code translates into a specific protein called pathogenic variant or mutation when linked to phenotypic particularly if they occur within the protein coding sequence of the gene. Variations are caused by the environment and genetic factors. Several disorders arise from multiple effectors like environmental, lifestyle, and

genetic factors. From these diseases is behavioral genetics neuropsychiatric, such as schizophrenia, depression in which a genetic fault transferred from parents to sons through familial genes causing elevated the risk of a particular disease. SNPs can affect more than 90% of genetic variation and are responsible for the occurrence of differences between the humans. Despite the presence of SNPs, there is no relation to modify or change cellular function that is to say have no effects, and at the same time, many SNPs were found to participate in the initiation of disease like cancer or act as prophylaxis against a certain disease or even impact the responses to medications. Depending on the SNPs' position in the genome, we can classify them into that happen with exome (coding region), intron (non-coding region), and between adjacent genes (intergenic region). Because there is much of non-coding DNA (99%) that lead to harboring majority of SNPs occurring in these segments. However, only small part (1%) of genome is considered important to represent exome that can contribute existing mutations, and SNPs that have a big outcome on several diseases. Non-coding genome includes many categories of regulatory factors such as promoters, enhancers, silencers, and insulators. Each one of them provides binding sites for proteins, carries out transcription, activates transcription, suppresses transcription, and controls transcription process, respectively.

SNPs are very important and used in various studies such as estimating the tendency to disease and predicting genetic lesion; and are also used as biomarkers since they can occur near disease genes for complicated diseases, but not always. In complex disease, which means a pathological circumstance of the body due to a defect in a number of genetic and environmental aspect, SNP can affect that person has toward a specific disease. Nowadays, various methods have been established and assembled to identify known or unknown SNPs through two categories which are genotyping and scanning sequence, respectively.
