Attempts to correlate this variable clinical expressivity with the residual functional activity of mutant FOXE1 protein have not been conclusive [37], and functional studies based on gel mobility-shift and transfection assays are needed to corroborate if p.(Gly124Arg) along with a 16 alanine polyAla tract represents a hypomorphic FOXE1 allele that retains considerable residual function to prevent the full development of Bamforth-Lazarus syndrome and only leave CH-TD as the phenotypic manifestation. This evidence concerns the gene FOXE1 and thanatophoric dysplasia.