Table 1. Characteristics of cases (SY group) and controls (no-SY group) in the discovery group (n=428).

Characteristic	Cases: SY Delta>avg. delta	Controls: no-SY Delta⩽avg. delta	P-value
N	218	210
Chronologic age, mean in years±SD	79.3±15.4	93.3±10.4	<0.0001
Delta SY, mean±SD	24.6±6.6	6.7±6.7	<0.0001
Female (%)	67%	70%	0.43
Body mass index (kg m−2), mean±SD	24.4±4.03	23.6±4.34	0.48
% With no family history of centenarians	65%	16%	<0.0001
Positive smoking history (%)	25%	37%	0.85
Positive personal history of skin cancer (%)	13%	18%	0.32

Abbreviations: GWAS, genome-wide association study; SAS, skin aging score; SY, skin youthfulness.

Cases and controls were identified using a global SAS incorporating intrinsic and extrinsic skin aging parameters. The average difference between CA and SAS (that is, CA minus SAS), or average “delta,” for the entire discovery group was 15.5. To avoid bias in assigning SY cases and SY controls for the GWAS, individuals whose “deltas” were greater than the average “delta” were defined cases (individuals with SY), and those whose “deltas” were less than or equal to the group average were defined as cases (individuals without SY). There were no individuals whose “delta” equaled the group average. P-values are calculated by Fisher's exact test or t-test to assess for significant differences overall between cases and controls. Examples of SY cases and SY controls are shown in Supplementary Figure S8 online.