In cardiomyopathy, the cardiac muscle cells become unusually thick and cause a distension of the heart itself, leading to reduced pumping volume and, in turn, escalating structural damage. Charting Human Disease Deoxyribonucleic acid, or DNA, consists chemically of four types of building blocks, or bases, that make up the genetic material of all organisms from bacteria to humans. Differences in the sequence of these building blocks account for small differences between individuals and larger differences between species. The human genome contains 3 billion base pairs of DNA and approximately 100,000 genes, located on chromosomes. The human genome project aims to determine the entire 3 billion base pair sequence.
Genes come in different forms called alleles.
Differing alleles arise by mutation. Some mutations are advantageous, but most are not and can sometimes lead to disease or a propensity for disease. Positional cloning involves the identification of disease-causing genes by determining the exact position of these genes on chromosomes. This approach does not require prior knowledge about the function of the disease gene. Identification of disease genes leads to an understanding of the biological causes of disease.