human genetics

Most of the emphasis is on understanding and treating genetic disease and genetically influenced ill health, areas collectively known as medical genetics. One broad area of activity is laboratory research dealing with the mechanisms of human gene function and malfunction and investigating pharmaceutical and other types of treatments. Since there is a high degree of evolutionary conservation between organisms, research on model organisms—such as bacteria, fungi, and fruit flies (Drosophila)—which are easier to study, often provides important insights into human gene function. Many single-gene diseases, caused by mutant alleles of a single gene, have been discovered. Two well-characterized single-gene diseases include phenylketonuria (PKU) and Tay-Sachs disease. Other diseases, such as heart disease, schizophrenia, and depression, are thought to have morecomplex heredity components that involve a number of different genes. These diseases are the focus of a great deal of research that is being carried out today. In addition,abnormalities in chromosomes have been identified by studies employing techniques such as chromosomal banding. Individual chromosomes are identified by the banding patterns revealed by different staining techniques.Segments of chromosomes or chromosomes that are aberrant in number and morphology may be precisely identified.Another broad area of activity is clinical genetics, which centres on advising parents of the likelihood of their children being affected by genetic disease caused by mutant genes and abnormal chromosome structure and umber. Such genetic counseling is based on examining individual and family medical records and on diagnosticprocedures that can detect unexpressed, abnormal forms of genes. Counseling is carried out by physicians with a particular interest in this area or by specially trained nonphysicians.