PTEN and Global developmental delay: IQ was reported in three studies in group A, and four studies in group B. Hansen-Kiss et al. [45] found that 15 of 47 participants (32%) identified as having a PTEN mutation, PHTS, CS or BRRS in their electronic records had an IQ of less than 80 (mean = 65), with 18 more (38%) having a documented history of intellectual disability or developmental delay.