CHI3L1 and androgen insensitivity syndrome: However, when the AIS patients were stratified according to their biological endophenotypes, the mean plasma ghrelin levels were significantly lowered in the FG1 endophenotype samples (99.9 ± 44.9 pg/ml) when compared with the controls (162.8 ± 63.9 pg/ml; P = 0.028) and could explain in part the elevation of YKL-40 in this AIS subgroup.