Eating behaviour phenotype in the MYT1L-related neurodevelopmental disorder: a deep phenotyping study using standardized questionnaires

Background The MYT1L-related neurodevelopmental disorder (MRND) is associated with global motor and language delay, intellectual disability, behavioural disturbances, epilepsy and frequent early-onset obesity. Eating disturbances have been reported but remain poorly characterized. A systematic characterization of the eating behaviour phenotype is essential to improve diagnosis and management. Methods We conducted a multicentre study including 21 French-speaking individuals with a molecularly confirmed MRND and either overweight/obesity or eating behaviour disturbances. Eating behaviours were reported by relatives using validated questionnaires widely employed in rare obesity research: the Dykens Hyperphagia Questionnaire (HQ), the Trousseau Impulsivity Questionnaire, the Children’s Eating Behaviour Questionnaire (CEBQ), the Food Cravings Questionnaire-Trait-reduced (FCQ-T-r, adults only), and a Visual Analogue Scale (VAS) for hunger. When available, questionnaire results were compared with published studies using the same instruments. Results Persistent hyperphagic behaviours were identified in the majority of patients, with the HQ questionnaire highlighting sustained food-seeking behaviours and pervasive food preoccupation. The mean global score was 25.9, indicating a moderate yet sustained hyperphagic profile. CEBQ revealed a strong attraction to food combined with reduced satiety responsiveness and rapid eating. Hunger was reported as persistent throughout the day. In children food impulsivity was less frequent (5/14; 36%) and no correlation was found between impulsivity and hyperphagia severity, contrasting with findings in other obesity syndromes. Among adults, 62.5% had scores suggestive of food addiction (FCQ-T- r ≥ 50). Conclusion This study delineates an eating behaviour profile in a symptom-enriched subgroup of individuals with MRND, characterized by moderate but sustained hyperphagia, persistent hunger, impaired satiety, low food-related impulsivity in children but frequent food craving/addiction in adults. These findings support early, age-adapted and multidisciplinary management strategies and highlight the need for targeted interventions to reduce the burden on affected individuals and families.