I've created a Ifrit Sorcerer with the fire bloodline. One of their abilities is Fire Affinity which reads:
Fire Affinity (Ex) Ifrit sorcerers with the elemental (fire) bloodline treat their Charisma score as 2 points higher for all sorcerer spells and class abilities.
However, this +2 Charisma is not taken into account in the DC of their spells.
PFS data sets, Java 1.8.0_91-b15