Linkage of X-linked Nephrogenic Diabetes Insipidus with DXS52, a Polymorphic DNA Marker
| Title: | Linkage of X-linked Nephrogenic Diabetes Insipidus with DXS52, a Polymorphic DNA Marker |
|---|---|
| Authors: | van Oost, Bernard A.; Monnens, Leo A.H.; Ropers, Hilger H.; Knoers, Nine; van der Heyden, H.; Willems, J. |
| Publisher: | Nephron |
| Date Published: | 1988 |
| Reference Number: | 260 |
In five families with X-linked nephrogenic diabetes insipidus (NDI), linkage studies with the DNA marker DXS52, defined by probe St14, have shown no recombination with a maximum combined lod score of 6.40. These results assign the NDI gene to the subtelomeric region of the X chromosome long arm. This finding should facilitate identification of carriers and should also be helpful in finding the NDI gene itself.
This translation by the NDI Foundation is to assist the lay reader. To provide a clear, accessible interpretation of the original article, we eliminated or simplified some technical detail and complicated scientific language. We concentrated our translation on those aspects of the article dealing directly with NDI. The NDI Foundation thanks the researchers for their work toward understanding and more effectively treating this disorder.
© Copyright NDI Foundation 2007 (JC)
In this type of analysis, researchers use genetic markers (genes, the location of which they know) that can be detected by restriction enzymes that can split DNA into specific, identifiable fragments. Researchers study the markers to see if they appear at a high rate with the gene they are looking for. If they do, and the probability that the correlation is the result of linkage (i.e. that the genes are close to one another), the researchers can have a better idea of the location of the gene they are looking for.
Knoers, et al., studied five families with NDI. This provided a total of 12 males with NDI and 58 unaffected family members (In X-linked diseases, males tend to express the disease; females tend not to). The authors took blood samples for DNA material and digested them with restriction enzymes. Using the DXS52 marker, which is identified by the St14 probe, they were able to distinguish between the X chromosome bearing the gene that, when mutated, causes NDI, and the X chromosome that did not carry the mutated version of this gene. They could make this distinction in all five families. That is, in each family the St14 probe always appeared with the appearance of NDI. And the St14 probe was not found in the X chromosomes of any of the males who did not have NDI.
This demonstrates linkage between the gene responsible for NDI and the DXS52 locus. DXS52 is located in the Xq28 region of the X chromosome. This indicates that the NDI gene is located in or near the same area of the X chromosome.
Now that the NDI gene location has been narrowed and a closely linked marker has been identified, there is an enhanced possibility of identifying females who carry the NDI gene.