These include MUC1, where a frameshift is causal for autosomal dominant tubulointerstitial kidney disease (ADTKD) (Kirby et al., 2013); CEL, where deletion mutations in the VNTR have been implicated in mature onset diabetes and other pancreatic disorders (Torsvik et al., 2010; Gravdal et al., 2021); and PER3, where VNTR length has been associated with diurnal preference and sleep homeostasis, and also with age of onset of bipolar disorder type I (Benedetti et al., 2008). Here, PER3 is linked to type 2 diabetes mellitus.