Table 1_Rare endocannabinoid system variants identified by whole-exome sequencing and structural modeling in adults with severe obesity predominantly of childhood onset.xlsx

Among the observed variants, FAAH p.(Arg326Pro) showed the most concordant predicted impact: it ranked as the most destabilizing substitution at position 326 by FoldX (ΔΔG = +3.04 kcal/mol; rank 1 of 19) and was the only observed variant classified as likely pathogenic by AlphaMissense (0.884). Arg326 lies 24.3 Å from the catalytic triad (Lys142–Ser217–Ser241), consistent with a predicted effect on fold stability rather than direct disruption of the active site.

Conversely, at DAGLA position 750, all 19 substitutions were predicted as neutral by FoldX and DDMut and as likely benign by AlphaMissense, consistent with predicted structural tolerance at this position. No anthropometric or metabolic parameter differed significantly between carriers and non-carriers after correction for multiple testing.</p>Conclusions<p>Rare ECS variants, including a previously unreported FAAH p.(Arg326Pro) substitution, were identified in adults with severe obesity, predominantly with childhood onset.

These in silico analyses are predictive and provide computational evidence for prioritizing candidate variants, notably FAAH p.(Arg326Pro); they do not, by themselves, establish pathogenicity or a causal relationship with the phenotype, which will require functional validation.</p>