Fragile X syndrome (FXS) is one of the rare diseases, a condition caused by pathogenic variation in the FMR1 gene (Fragile X Messenger Ribonucleoprotein 1) on the X chromosome due to expansions of the CGG trinucleotide repeat, affecting the function of the gene.1, 2 The prevalence of FXS is estimated to be approximately 1 in 7000 men, although the exact numbers are unclear.3 The gene discussed is FMR1; the disease is fragile X syndrome.