Abstract
This chapter focuses on the Human Genome Project (HGP), which determined that humans have between 20,000 to 25,000 protein-coding genes and only about 1.5% of the genome codes for proteins, rRNA, and tRNA. The remainder once referred as “junk DNA” is today known to be crucial to survival of the species. Research indicates that genes are not contiguous, and some genes occur within the introns of other genes; some genes can overlap with each other either on the same or on different DNA strands with shared coding and/or regulatory elements; plus, the vast majority of human genes undergo alternative splicing leading to different proteins being encoded by the same gene. Advances in genomics and gene sequencing technologies have created exceptional opportunities for the delivery of personalized medical care. Clinical genetic testing has been helpful in identifying gene variants associated with risks for a number of diseases and health conditions.