New Study on the Relationship Between the Fragile X Messenger Ribonucleoprotein (FMRP) and the Development of Speech and Vocabulary in Young Boys living with Fragile X Syndrome

Contributors Stephen R Hooper, John Sideris, Deborah R Hatton and Joanne R Roberts have successfully published a groundbreaking new study titled “The Contribution of FMRP to the Development of Speech and Vocabulary in Young Boys with Fragile X Syndrome: A Retrospective Examination”.  Using a sample size of 45 boys under 16 who live with Fragile X Syndrome (FXS), the authors made a significant contribution to understanding how the presence of FMRP impacts the relationship between development level of speech, expressive vocabulary, and receptive vocabulary of young boys living with FXS. 

Background

The deficiency of the FMR1 protein (which is essential for neurotypical brain functioning) results in difficulties in physical and neurological development in people living with FXS. However, there have been very few studies exploring the relationship between FMRP and the development of speech and language skills in young boys with FXS. Examining this relationship is important, as the general consensus is that while young boys living with FXS display ‘moderate to severe’ language difficulties, the development of their receptive language progresses better than their expressive language. A 2007 study by Roberts et al found that boys who live with both FXS and autism displayed more difficulties with expressive vocabulary than younger neurotypical boys after adjusting for nonverbal cognitive abilities (page 2). Due to its relationship with several genes linked to autism, FMRP is therefore of significance to both the FXS and autism communities. The study is one of the first of its kind as it provides an in-depth analysis of communication skills of young boys living with FXS as they develop over time. 

The Study 

45 boys under the age of 16 who live with FXS participated in the study. They were grouped into those who live with both autism and FXS and those who live with FXS (without autism). The investigators used three methods to test the correlation between FMRP and speech articulation (pages 6-7), expressive vocabulary (page 8) and receptive vocabulary. The results presented evidence that while FMRP did not have a direct relationship with the development of these three avenues of communication (page 11), it ‘moderated’ the relationship between mental age, autism status and speech development, and expressive and receptive vocabularies. The higher the levels of FMRP, the more increased the relationship was between these variables in both boys living with FXS and autism, and FXS only. Lower levels of FMRP showed that these relationships were weak in both sets of boys. 

Important Takeaways from the Study 

This work finds that FMRP is vital in moderating the relationship between autism status, developmental levels, and speech and vocabulary development in boys living with FXS (page 11). Although this relationship is complex, there is room for further exploration. The study also found in their sample size no significant relationship between maternal education and language development of boys living with FXS. This is surprising, as it contradicts previous research that suggests a strong connection between maternal education and environmental influences to language and behavioural development in people living with FXS. 

Overall, higher levels of FMRP appeared to enhance the relationship between the development levels and outcomes for boys living with FXS with and without autism.