We have created a map-based tool that annotates the genes and chromosome regions with clinical relevance when either duplicated or deleted. As the clinical effects are due to abnormal gene dosage, we are referring to this tool as a gene dosage maps.

These gene dosage maps have been created using sets of genome annotation tracks on the UC Santa Cruz Genome Browser. These tracks display the genes and phenotype regions based on their chromosomal location with links to information about their potential role in generating an abnormal phenotype. We have created two types of tracks.

  • Gene Dosage Tracks: Each gene is depicted by location and classified with regard to the likelihood of being dosage sensitive. There is 1 track for the effects of hemizygosity (gene deletion) and one for suprazygosity (gene duplication).
  • Phenotype Track: This track indicates the locations of the regions for specific phenotypic features that are linked to a region of chromosome 18 but for which the causative gene has not yet been identified.

Learn how to use a Gene Dosage Map and about the clinical utility of a molecular diagnosis. For those interested in only those genes and regions currently classified as having clinical significance, we have created a map that includes only those data:

Paths to treatment

One of the major goals of the Chromosome 18 Clinical Research Center is to develop treatments for conditions involving chromosome 18. This is a multi-step process that takes years. Learn more about our process


The 18q- syndrome has made the most progress. This is primarily due to the commitment of a single family who donated sufficient money to jumpstart and sustain the research. The identification of chromosome regions linked to specific features of 18q is well underway. Work is now focused on identifying which genes are the key genes. In addition the clinical assessment is continuing to ask more and more precise questions so that the features and the causes can be understood from a clinical perspective.

Additionally we have one study to determine the effects of growth hormone therapy – which highlights the fact that this is not a rigidly linear process.


The literature review on 18p- has been available for some time on the Registry website. A clinical assessment of 10 individuals with 18p- was performed and published in 2002. Molecular characterization and compilation of medical records is ongoing.


The literature review of tetrasomy 18p has been on the Registry site for several years. An in-depth clinical assessment of 43 individuals with tetrasomy 18p was published in 2010. An additional manuscript on the neuropsychological finding will be submitted for publication soon.


A literature review of Ring 18 has been on the Registry website for many years. Because almost all individuals with Ring 18 have a deletion of both the p arm and q arm, they have characteristics of both conditions. The literature review did not detect any features that were new or novel to those with Ring 18 compared to 18q- and 18p-. A report of the molecular characterization of 20 individuals with Ring 18 is being finalized for publication.


Trisomy 18 is unlike the other chromosome 18 conditions in two ways. First, it is not rare and second the affected children are very medically fragile and have a shortened life expectancy. This means that research on trisomy 18 has the most potential for making dramatic improvements. However, research to this point has not progressed beyond the literature review.