Were a lot of people with fragile x misdiagnosed in the past?

Fragile x. I think many things past and present can be misdiagnosed. Especially when genetics are involved. Research and technology making it better every year. This article may help. http://autismandoughtisms.wordpress.com/2011/08/04/genetic-origins-of-autism-when-is-autism-not-autism-fragile-x-and-rett-syndrome/.
Certainly. The male linked pattern of mental deficiency was first reported in the 1940's but the fragile X was first reported in 1969. It took several years before the information was general knowledge and testing more common. Then as now. many vague problems were lumped into unexplained patterns of mental deficiency. We will find more defect related issues (like autism) as the technology progresses.