Fragile X Syndrome

The fragile X chromosome means that the chromosomes between the Xq27 to Xq28 bands are filament-like, causing the connected ends to have satellite-like structures. Because this filament-like site is prone to fracture. It is called a fragile site. The X chromosome with a fragile site at Xq27 is called fragile X chromosome, referred to as fra (x), so the disease caused by it is called fragile X syndrome (OMIM 309550). A large amount of data shows that the incidence of fra (x) accounts for about 1/2 to 1/3 of patients with X-linked intellectual dysplasia. In the general male group, the detection rate is 1.8 / 1000. Its incidence is second only to the congenital type (Down syndrome).