Irene Adler's Hair Sample: DNA Testing & Strategic Manipulation

Irene Adler takes the hair sample to a forensic lab to have it DNA tested. She does this to confirm that the hair belongs to Sherlock Holmes. She needs this confirmation to manipulate him further as part of her plan to protect herself and those she cares about. The DNA result would be used as a bargaining chip to gain leverage over Sherlock, if required.