Click here to read the full research paper by Lydia Cartwright, Gaia Scerif, Chris Oliver, Andrew Beggs, Joanne Stockton, Lucy Wilde, and Hayley Crawford.

רֶקַע 

Previous studies have shown that Fragile X Syndrome (FXS), despite being monogenic or involving one gene, results in varied behavioural outcomes due to individual variability in its phenotypic profile.These studies have shown such behavioural variation is linked to  5-HTTLPR (serotonin) and COMT (dopamine) single nucleotide polymorphisms (SNPs) when measured cross-sectionally. However, the nature of the relationship between SNPs and longitudinal behavioural trajectories in FXS is unknown. 

The authors of this study explored relationships between three SNPs (5-HTTLPR, COMT and monoamine oxidase A (MAOA)), and trajectories of clinically relevant behaviours in 42 male participants living with FXS.The study categorised these behaviours as ‘autistic characteristics, property destruction, aggression, stereotyped behaviour, self-injury, repetitive behaviour, and mood/interest and pleasure’. These were measured at two time points across three years via a series of standardised informant questionnaires, along with DNA extractions and genotyping. 

Findings 

The study found that ‘persistent stereotyped’ behaviour was less prevalent in males living with FXS with AA COMT genotype compared to AG or GG genotypes. Participants with the S/S 5-HTTLPR genotype showed a more prominent decline in repetitive and stereotyped behaviours compared to the L/S or L/L genotypes. Communication skills in participants with the three-repeat MAOA genotype appeared to decline faster over three years compared to those with four repeats. The authors believe that these findings may assist in developing future tailored interventions and our understanding of individual trajectories for people with FXS.