ESPE Abstracts

Introduction: Besides an excessive, early-childhood weight gain, hyperphagia is the key symptom in patients with monogenic obesity. However, the assessment of hyperphagia is still challenging. Here, we applied the hyperphagia questionnaire developed for patients with Prader-Willi-Syndrome (PWS) to assess the severity of hyperphagia in patients with monogenic obesity.

Methods: Pediatric patients with biallelic pathogenic leptin receptor (LEPR) variants, heterozygous pathogenic melanocortin-4 receptor (MC4R) variants and 16p11.2 microdeletion including deletion of Src homology 2B1 (SH2B1) were recruited from our outpatient clinic. The 13-item hyperphagia questionnaire from Dykens et al. (2007), developed and validated to assess hyperphagia in patients with PWS was completed by their parents. All items were summarized in a total hyperphagia score and its subscores hyperphagic behaviour, hyperphagic drive and hyperphagic severity.

Results: Twenty children with monogenic obesity (mean age 9.67 ± 6.10, mean BMI SDS 3.90 ± 0.91) were included in the analysis, thereof 8 patients with LEPR variants, 7 patients with MC4R variants, and 5 patients with 16p11.2 microdeletions. There were no group differences except for a significant higher BMI SDS in patients with LEPR variants (4.70 ± 0.79) compared to patients with MC4R variants (3.36 ± 0.73, P = 0.004) and 16p11.2 deletions (3.39 ± 0.38, P = 0.015). The hyperphagia questionnaire showed a significant group difference only in the total hyperphagia score (p = 0.025). A post hoc analysis revealed significantly higher total hyperphagia scores in patients with LEPR (32.0 ± 9.32, P = 0.019) and MC4R variants (31.4 ± 5.44, P = 0.018) compared to patients with 16p11.2 deletions (21.4 ± 5.46). Furthermore, patients with 16p11.2 deletions had hyperphagia scores similar to previous published obese controls. Regardless of genetic variant, there was a moderate negative correlation between patients age and the scores total hyperphagia (r = -0.456, P = 0.043) and hyperphagic behavior (r = -0.516, P = 0.020).

Conclusion: The hyperphagia scores indicate that the severity of hyperphagia is comparable in patients with biallelic LEPR and heterozygous MC4R variants. Consistent with parental narratives, patients with 16p11.2 deletions show hyperphagia scores indicative of less severe hyperphagia than patients with LEPR or MC4R variants. In addition, the inverse relationship between age and total hyperphagia score and between age and hyperphagia behavior subscore suggests that the severity of hyperphagia declines with age, with the highest scores in infancy and preschool age. Overall, the hyperphagia questionnaire for patients with PWS is a useful tool to assess the severity of hyperphagia in patients with monogenic obesity.