Human Genome News, July 1991; 3(2)
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Human Genome News, July 1991; 3(2)

NCHGR Begins Unified Framework Map Effort

Expected to facilitate gene hunting


Investigators funded under the NIH National Center for Human Genome Research (NCHGR) Human Genome Program have begun a new, unified effort to develop a framework map of index markers for each chromosome of the human genome. Expected to take 2 to 3 years to complete, these maps will consist of an ordered set of special, high-quality index markers that will help scientists pinpoint genes or other genetic determinants more quickly. Once investigators narrow down a gene's location to an interval on the framework map, they can limit their search to the chromosome segment between the specific index markers.

"This is a crash program to get a series of really good markers out into the hands of the research community quickly so they can use them to go after genes," says James D. Watson, Director of NCHGR. "The plan is that the markers will go into a central repository where they will be available to everyone." The location of this repository is pending.

The concerted NCHGR effort to construct index maps grew out of a 1990 meeting of the NIH-DOE Joint Mapping Working Group. On March 22 in Salt Lake City, meeting participants noted that only a small fraction of the human chromosomes were well mapped. They identified as high priority the development of a framework map composed of about 300 highly polymorphic markers spaced 10 cM apart. The participants also agreed that the process would be speeded up by asking individual investigators to assume responsibility for seeing that the framework maps of specific chromosomes were completed.

The NIH Program Advisory Committee on the Human Genome approved the plan on June 18. A request for research project grant applications (RFAs) was issued shortly after, and grants have now been awarded (see NCHGR Index Marker Mapping Projects).

The goal of the Human Genome Project for linkage mapping is to eventually develop a map on which DNA markers, each identified by a sequence tagged site, are spaced an average of 2 cM apart with no gaps greater than 5 cM. Framework maps of index markers are part of the plan to produce a highly detailed genetic linkage map of the human genome. Genetic linkage maps, which describe the order of and distance between markers and genes, are made by following the inheritance of traits in families. Because traits that are frequently inherited together are usually close together on a chromosome, researchers can use a nearby landmark that is easier to monitor to follow the inheritance of another trait.

About 2000 polymorphic human markers have been isolated, but 90% of these do not have high enough frequency of variation in the population to be incorporated into a framework map. In addition, their distribution is not evenly spaced throughout the genome. The currently available markers produce a map in which some regions contain a number of tightly clustered markers while other areas have few or none. The framework map will differ from existing linkage maps in that all markers will be particularly scientifically and medically useful.


HGMIS Staff

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Human Genome Project 1990–2003

The Human Genome Project (HGP) was an international 13-year effort, 1990 to 2003. Primary goals were to discover the complete set of human genes and make them accessible for further biological study, and determine the complete sequence of DNA bases in the human genome. See Timeline for more HGP history.

Human Genome News

Published from 1989 until 2002, this newsletter facilitated HGP communication, helped prevent duplication of research effort, and informed persons interested in genome research.