Usefulness of fragile X checklist and CGG distribution in specialized institutions in Kinshasa, DR Congo

Area of Science:

• Genetics
• Neurodevelopmental Disorders
• Public Health

Background:

• Fragile X syndrome (FXS) screening is crucial for children with developmental delay or intellectual disability (ID).
• Clinical screening checklists are valuable in resource-limited settings for FXS identification.
• Understanding FXS prevalence and CGG allele distribution is vital for targeted screening.

Purpose of the Study:

• To determine the prevalence of FXS and CGG allele distribution in specialized institutions in Kinshasa, DR Congo.
• To evaluate the effectiveness of three clinical screening checklists (Hagerman, Maes, Guruju) for FXS in this population.
• To assess the applicability of existing FXS screening tools in a Congolese context.

Main Methods:

• Recruitment of 80 males and 25 females from six specialized institutions in Kinshasa.
• Administration of a questionnaire based on Hagerman, Maes, and Guruju FXS checklists.
• Molecular assessment of FMR1 CGG repeats for all participating patients.

Main Results:

• Referral rates for FXS testing were 37% (Hagerman), 35% (Maes), and 43.80% (Guruju).
• No molecular confirmation of FXS was found, indicating low positive predictive values for the checklists.
• Specificities were calculated as 62.86% (Hagerman), 64.76% (Maes), and 56.5% (Guruju).
• The mean CGG allele size was 28.55 ± 2.83, with the 29-CGG allele being the most frequent (24.61%).
• CGG repeat distribution aligns with findings from other African studies.

Conclusions:

• Existing FXS screening checklists require adaptation before use in Congolese populations.
• The low specificity suggests these tools may not be suitable for direct application without modifications.
• Further research is needed to develop culturally and contextually relevant screening strategies for FXS in the region.