Scoring Variation in the

Differences in alleles can be scored via laboratory testing. The ability to score allele differences accurately within families, between families, and between laboratories is critically important for linkage analysis in both simple Mendelian and genetically complex common disorders. Linkage analysis traces coinheritance of a disease gene and polymorphic markers such as SNPs to discover where in the chromosomes the disease gene is located.

Allele scoring strategies may be as simple as noting the presence (+) or absence (-) of a deletion or point mutation, or as complicated as assessing the allele size in base pairs of DNA. The latter application is common when highly polymorphic; microsatellite repeat markers are used in linkage analysis.

When genetic counselors talk to patients and families about mutations (a type of genetic variation) that are present in themselves or their children, they are careful to point out that each individual is estimated to carry between five to seven deleterious alleles that, in the right combination with other genes or with specific environmental influences, can lead to disease. Most of us do not know which deleterious genes we carry. Some are recessive and do not influence the genotype unless paired with a second recessive allele. Thus, these alleles will not be noticed without genetic analysis. And, genetic counselors are careful to avoid the term "mutation," because it is potentially stigmatizing. When speaking with patients, they prefer to use the more neutral term "variant." see also Disease, Genetics of; Genotype and Phenotype.

Marcy C. Speer


Internet Resources

SNP Consortium, Ltd. <>.

"Human Genome Project Information." U.S. Department of Energy. <http://www>.

Information Systems Manager

An information systems manager (ISM) is a professional whose skills are needed to handle the large amounts of information generated by and analyzed in the modern genetics laboratory. A successful information systems manager needs to be experienced with the technical aspects of computer hardware and networking systems. The daily work may involve managing a team of information technology workers, so leadership and management skills are usually a necessary qualification. Like most jobs in the scientific and technical areas, this one involves interacting regularly with staff, other units, upper management, and scientists, so that proficiency in oral and written communication is essential. Although an information systems manager is not usually required to have a deep understanding of the genetic sciences, the ISM must be well acquainted with the information needs of the organization and must possess advanced technical knowledge.

The training needed for a career as an information systems manager begins with formal education and training in computer programming, database fundamentals, systems analysis and design, data communication, and networking, all at the undergraduate level. A major, or at least a concentration, in information systems management at either the bachelor's or master's degree level will also provide a solid foundation for a position as an ISM. Many information systems managers begin their career as systems analysts, programmers, or computer engineers, or were in other computer-related positions. An in-depth understanding of computer technology and applications will make the candidate attractive for many other careers as well, since the projected outlook for all computer-related professions is continued growth through 2008.

The duties of an ISM can be quite diverse. They include setting up networks, including the installation of lines, hardware, and software; administering servers; programming; and setting up intra- and internets. ISMs may even be called upon to do some Web page design. An information systems manager is not an entry-level position, as the ISM has considerable administrative duties. The job requires hiring, training, assigning, and supervising computer specialists so that each employee does his or her particular duty toward meeting the organization's goals. In addition, ISMs need strong budgeting skills and the ability to communicate with contractors, suppliers, and financial groups, for they are involved in making decisions concerning equipment purchases.

The majority of ISMs do most of their work from an office, but may be called upon to go to the client's site to set up networks, hardware, or software. This may include doing their work in research laboratories, where they may be exposed to hazards arising from the investigations being conducted there. ISMs often work under stringent time and budgetary contraints. It is not unusual for ISMs to work more than forty hours per week.

The job can be rewarding when the organization makes progress in meeting their goals. There is usually plenty of room for personal growth, as many ISMs are advanced to higher managerial positions. ISMs typically enjoy a good salary and a substantial benefits package. Salaries usually range from $45,000 to $120,000 per year, with most earning between $50,000 and $95,000. The amount earned depends on education, the amount of experience, and whether the job is in the public, academic, or private sector. Workers in state government usually earn the least, with a median annual income of $63,500, while workers in industrial settings earn the most, with a median annual income of $87,500. see also Bioinformatics; Computational Biologist; Statistical Geneticist.

Judith E. Stenger


Ahituv, Niv, and Seev Neumann. Principles of Information Systems for Management.

Dubuque, IA: Wm. C. Brown Company, 1983.

Information Systems Manager


Alter, Steven. Information Systems: A Management Perspective, 2nd ed. Menlo Park, CA: Benjamin/Cummings Publishing Company, 1996.

Internet Resource

U.S. Bureau of Labor Statistics. Occupational Outlook Handbook, 2000-2001 edition. U.S. Department of Labor. Washington, DC, 2000. < ocohome.htm>.

Inheritance, Extranuclear i mitochondria energy-producing cell organelle chloroplasts the photo-synthetic organelles of plants and algae cytoplasm the material in a cell, excluding the nucleus

Less than a decade after the rediscovery of Mendel's laws describing the inheritance of genes in the nucleus, hereditary traits were discovered that obey a different set of laws. The genes involved in this non-Mendelian pattern of inheritance reside outside the nucleus, in the cytoplasm of the cell. Specifically, they were found to reside in mitochondria, chloroplasts, or intracellular symbiotic bacteria. Those genes play important roles in the cell. Mutations in extranuclear genes are responsible for some hereditary diseases in humans and other organisms, are used in plant breeding, and are used to study population genetics and evolution.

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