California Code, Health and Safety Code - HSC § 1644.8

Any entity that receives genetic material of a human being that may be used for conception shall make available to the person depositing his or her genetic material a form that, if signed by the depositor, would revoke any previous expression of intent regarding the use of his or her genetic material necessary to satisfy the conditions set forth in Section 249.5 of the Probate Code. The use of the form is not mandatory, and the form is not the exclusive means of expressing a depositor's intent with respect to revocation or amendment of a prior expression of intent. The form shall include advisements in substantially the following form:

“The use of this form to revoke or amend a previous form for designating whether a child conceived after your death will be your heir is not mandatory. This specification can be revoked or amended only in a writing signed by you (and not by spoken words).

These issues can be complex, and you should discuss them with your attorney.”