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.
Males have only one X chromosome, which is inherited from the mother at conception, and they receive a Y chromosome from the father. Females inherit two X chromosomes, one from each parent. Fragile X syndrome is caused by a mutation in a gene called FMR-1.This gene is located on the X chromosome.The FMR-1 gene is thought to play an important role in the development of the brain, but the exact way that the gene acts in the body is not fully understood.ragile X syndrome is the most common form of inherited mental retardation. Individuals with this condition have developmental delay, variable levels of mental retardation, and behavioral and emotional difficulties.