Optimized models for age estimation should aim at the inclusion of as many robust CpGs as possible; for growth disorders, such robust CpGs are for example CpG1, CpG2, CpG5, CpG8 and CpG9 in ELOVL2. Our 5 CpGs models which contained only these robust CpGs obviously performed somewhat better on test samples of diseased children (Fig. 3; Table 3). Here, ELOVL2 is linked to hereditary endocrine growth disease.