This can also be called small-for gestational age (SGA) or fetal growth restriction. There are basically two different types of IUGR: Symmetric or primary IUGR is characterized by all internal organs being reduced in size. Symmetric IUGR accounts for 20% to 25% of all cases of IUGR.
Fragile X syndrome (FXS), also known as MartinâBell syndrome, or Escalante's syndrome (more commonly used in South American countries), is a genetic syndrome.
It is the most common form of inherited mental retardation. Fragile X syndrome is caused by a mutation in the FMR-1 gene, located on the X chromosome. The role of the gene is unclear, but it is probably important in early development.