DWARFISM | Ex

Mutated genes have altered your physical size, and you are reduced by 1 size category. This change in size make you noticeably different from other of your species. 

This mutation causes you to shrink, halving your height, length, and width and dividing your weight by 8. This decrease changes your size category to the next smaller one. You gain a +2 size bonus to Dexterity, a -2 size penalty to Strength (to a minimum of 1), and a +1 bonus on attack rolls and EAC and KAC due to your reduced size.

A Small humanoid creature whose size decreases to Tiny has a space of 2-1/2 feet and a natural reach of 0 feet (meaning that it must enter an opponent’s square to attack). A Large humanoid creature whose size decreases to Medium has a space of 5 feet and a natural reach of 5 feet.

You can no longer wear armor or use some types of equipment designed for Medium humanoid creatures.  Natural attacks and unarmed strikes deal less damage (see Table 10-1: Tiny/Large Damage).