As our DNA testing technology improves, we have been able to focus on the genetic cause of Fragile X syndrome.
Older techniques, originally looking at the chromosome (package of many genes), used to identifiy an additional cause for Fragile X syndrome – Frax E. Although it is caused by a different gene on the X chromosome, Frax E causes similar phenotype/symptoms.
This highlights the ongoing importance of considering other causes of ‘X-linked intellectual disability’, if a diagnosis has not been made in children with intellectual disability.