FOXE1 and thanatophoric dysplasia: Although the homozygous Ala-14-FOXE1 genotype significantly increases the risk of TD, as shown by our CH cohort (Figure 3B), variations in FOXE1 polyalanine repeats are not sufficient to induce CH per se, as around one third of the healthy population has the homozygous Ala-14 tract (Figure 3A) (15, 17, 19, 37).