| Fall 2002 CARES Foundation, Inc. | |
| |
| Back to Fall 2002 Index | |
|
The Use of Second-Tier Molecular Screening for Improving the Sensitivity and Specificity of CAH Newborn Screening Edwin Naylor, Ph.D., MPH, President and Laboratory Director of NeoGen Screening, Inc. |
|
|
| A common problem in newborn screening for CAH is that the positive cut-off for 17-hydroxy-progesterone (17-OH-P) is generally set in order to minimize the false positive rate. While this is effective in detecting newborns with salt wasting CAH it misses most cases of non-classical or late onset CAH and some simple virilizing cases. On April 1, 2001, Neo Gen Screening, Inc. received a Small Business Innovation Research grant from the National Institutes of Health to develop second-tier molecular assays for the common CYP21 mutations that cause CAH. These assays will be performed on the original filter paper blood specimen collected in the newborn period whenever there is an elevated 10-OH-P. This will permit us to lower the initial cut-off level while at the same time increasing sensitivity and specificity. It will also permit us to detect significantly more cases of non-classical or simple virilazing CAH than we can using 17-OH-P alone.
In this project we are amplifying the DNA present in the filter paper blood specimen to give us more material to work with and we then use Fluorescence Resonance Energy Transfer (FRET) probes to identify specific CYP21 gene changes. This technology is call "Light Cycler" analysis and is a new and very rapid process that permits us to have our molecular results the same day that we run the newborn screen. We are currently completing the validation of these assays and have begun screening known cases of CAH that we detected at Neo Gen Screening as well as well as cases sent to us from Pittsburgh Children’s Hospital, Indiana, and Brazil. These methods will detect the presence of deletions and duplications of the CYP21 gene and will permit us to identify up to 10 of the most common gene changes including the common I2, 8 bp del 706-713, I172N, Q318X, R356W, InsT, P453, P30 and the non-classical V281L mutations. We expect to complete the validation phase by April 1, 2003 and to incorporate it into our routine newborn screening procedures and to offer it to high risk patients on a diagnostic basis.
|
||||
| ||||
 | ||||
| © 2002 CARES Foundation, Inc. All rights reserved. Republication or redistribution of CARES content, including by framing or similar means, is prohibited without the prior written consent of CARES. | ||||