Fragile chromosome x syndrome: Sequelae in feet and a case report

Fragile chromosome X syndrome is the prime cause of hereditary mental retardation and the second most frequent chromosomopathy after Down's syndrome [1,2]. It is estimated to affect one in 4000 males and that there is one female carrier per 800 and one male carrier per 5000 [3,4]. The inactivated gene FMR1 codifies the disease and is altered at locus Xq27.3 (long arm of chromosome X) [1,5]. This gene determines the non-production of the protein FMRP [2,6,7] the deficiency of which causes the disease, as this protein is essential in the regulation of neuronal changes, stimuli, and maturation — that is, of the development of the nervous system — and also affects the development of connective tissue [3], the cause of the articular hyperlaxity presented by these patients [2]