Influence of Polygenic Risk on Height and BMI in Adults With a 22q11.2 Microdeletion

Context: Elevated a priori risk may enhance the likelihood that common variant effects, captured collectively in a polygenic risk score (PRS), approach clinical utility. Objective: In this study, we investigated the modifying effect of PRSs for adult height and body mass index (BMI) in individuals with elevated baseline risk for short stature (<3rd percentile height) and obesity (BMI ≥30) conferred by a 22q11.2 microdeletion. Methods: We tested height-PRS and BMI-PRS for association with their respective phenotypes in 259 adults of European ancestry with a 22q11.2 microdeletion using sequencing data and multivariable linear regression models to account for clinical/demographic variables. Results: In multivariable linear regression models, height-PRS and BMI-PRS explained 25.8% and 5.7% of the variance in their respective traits (P < .001 for both). When applying the height-PRS to stratify risk for short stature, 42.3% of individuals in the lowest PRS quintile had short stature (vs 5.9% in the highest PRS quintile, odds ratio = 11.46, P = 1.74E-05). Using logistic regression models to predict short stature in a receiver operating characteristic curve analysis, a model combining height-PRS and clinical/demographic covariates achieved an area under the curve of 0.78, performing significantly better than a covariate-only model. Conclusion: The results demonstrate that adult height and BMI can be influenced by the effects of genome-wide common variants in the presence of a rare variant conferring elevated a priori risk. Height-PRS may help refine growth expectations in individuals with 22q11.2 microdeletion.