However, allelic series in both genes are rather intriguing; extensive variant analysis on genotype-phenotype correlation of GLI3 discovered a unique dichotomous relationship between the typical Greig cephalopolysyndactyly syndrome (GCPS) spectrum (MIM: 175700) and a more severe AD disorder called Pallister-Hall syndrome (PHS; MIM: 146510), depending on the location (i.e., genomic map position) of the causative variant allele.63 This evidence concerns the gene GLI3 and Greig cephalopolysyndactyly syndrome.