Family trees
The The complete set of DNA found in an organism. of an organism is the entire genetic material of that organism. The sequence of letters in the human genome has been determined, but research is still ongoing. Understanding the human genome has great importance for medicine.
Research on the human genome enables us to:
- search for The basic unit of genetic material inherited from our parents. A gene is a section of DNA which controls part of a cell's chemistry - particularly protein production. linked to different types of disease
- understand inherited disorders and devise treatments
- trace human migration patterns from the past
Scientists are searching for disease associated genes. One example is the genes that can contribute to breast cancer, which are known as BRCA1 and BRCA2. A random and spontaneous change in the structure of a gene, chromosome or number of chromosomes. in these genes account for approximately 10% of all inherited breast cancer cases detected.
Scientists detected BRCA1 and BRCA2 genes by studying individuals in families known to have inherited breast cancer. They were able to create a pedigree analysis, which is similar to a family tree diagram, that showed the close relationship of those affected and unaffected within the family.
The pedigree analysis illustrates the inheritance pattern of the disease.
In the pedigree analysis chart below, males are indicated by the square shape and females are represented by circles. Affected individuals are red and unaffected are blue. Horizontal lines between males and females show that they have produced children.
This analysis shows both males and females are affected, and every generation has affected individuals. There is one family group that has no affected parents or children, but the remaining two families have one affected parent and affected children too.
