The overlapping region comprises exon 4, which is evolutionarily conserved and lies within a small CpG-rich region that lacks differential methylation [160]. It is also possible that the identified deletions independently disrupt a large control element that spans STX16. On the other hand, disruption of STX16 is not considered to be involved in the pathogenesis of PHP-Ib, because there is no evidence that this gene is imprinted [160, 164].
