Fragile X syndrome is also called as Martin–Bell syndrome, or Escalante's syndrome is a genetic syndrome. Nearly half of all children with fragile X syndrome meet the criteria for a diagnosis of autism. It is an inherited cause of intellectual disability especially among boys. It is caused by defect in chromosome Xq 27.3 .
Aside from intellectual disability, prominent characteristics of the syndrome may include an elongated face, large or protruding ears, flat feet, larger testes and low muscle tone. Recurrent otitis media and sinusitis is common during early childhood. Speech may be cluttered or nervous.
Fragile X syndrome is a genetic disorder which occurs as a result of a mutation of the fragile X mental retardation 1 (FMR1)gene on the X chromosome, most commonly an increase in the number of CGG tri nucleotide repeats in the 5' un translated region of FMR1.
Fragile X syndrome is recognized as the most common inherited cause of mental retardation in western countries. The prevalence of the fragile X syndrome in Asian populations is uncertain. According to one report a multi-institutional collaborative study of molecular screening for the fragile X syndrome from 1,127 Chinese mentally retarded (MR) individuals.