To explore the association between autism phenotype and FMR1 protein (FMRP), FMR1 mRNA and CGG repeat length in 31 male FMR1 premutation carriers aged 3.0 to 27.9 years old (mean 13.0 ± SD 6.5) using the ADOS communication, social interactive and total scores. FMRP levels were determined using the sandwich Enzyme-linked Immunosorbent Assay (ELISA) method, FMR1 mRNA expression levels were measured by qRT-PCR, and CGG repeat size was determined using Southern blot and PCR analyses. There was no significant difference in FMRP, CGG repeat length, and FMR1 mRNA between fifteen subjects without (ASD / PDDNOS / autism and sixteen subjects with ASD / PDDNOS / autism. ADOS scores were not significantly associated with either FMRP or FMR1 mRNA, This preliminary evaluation found that autism phenotype is not associated with the level of expression of either FMR1 mRNA or FMRP. However, CGG was significantly negative associated with both ADOS communication score (p= 0.0173) and ADOS total score (p= 0.0358).This work was supported by National Institute of Health grants HD036071, HD02274, DE019583, DA024854, AG032119, AG032115, MH77554; National Center for Advancing Translational Sciences grant UL1RR024146 and UL1TR000153; and Health and Human Services Administration of Developmental Disabilities grant 90DD05969
