Collagen screening studies are undertaken as a means of identifying the protein (in this case, collagen) abnormality typically seen in cells from an individual with the vascular form of Ehlers-Danlos Syndrome (vEDS). If the type III collagen in the cells from the patient studied is identical to the collagen pattern of the control (normal) sample, the result is reported out as "no abnormality detected". This negative result is often described in detail in the result letter, including the fact that there may be rare instances when the collagen screening study does not detect or confirm the clinical diagnosis. The sensitivity of the collagen screening test is not 100% - it is closer to 98%. If the physician still suspects that the patient has vascular EDS, additional DNA-based testing can be considered on a case by case basis. Answered by Melanie Pepin, MS,CGC