I wrote this response below to address a recent New York Times article: Confirming a Diagnosis of Celiac Disease.
The reality of gluten sensitivity is that around 7 to 12% of the US population test positive for antibodies which are an indicator that their immune system is mounting a response to gliadin, the part of gluten that causes the reaction in those who are sensitive. Many of these people may never get flattened villi, however, many may end up with other conditions that are triggered by gluten exposure in sensitive individuals, for example nerve damage (ataxia), liver problems, diabetes, thyroid issues, etc..
In the past 10 years the diagnostic criteria for celiac disease have been changed significantly to include various degrees of villi damage (Marsh Criteria), and as a result, more people are now being properly diagnosed. In the next 10 years I predict that blood tests alone will replace the use of all biopsy results to diagnose celiac disease, as they are a far more sensitive indicator of gluten sensitivity. Once this happens we will finally reach a point where those affected can be properly treated and avoid the risk of the many disorders that have been associated with sensitive individuals who eat gluten, some of which are described here.