U.S. Citizenship and Immigration Services (USCIS) issued a memorandum in 2014 stating that it would not consider DNA analyses as evidence of a sibling relationship when adjudicating a petition filed by one sibling on behalf of another. In a published decision, the Board of Immigration Appeals (BIA) ordered USCIS to consider DNA evidence when adjudicating sibling petitions. Specifically, the BIA stated that "sibling-to-sibling DNA test results reflecting a degree of certainty of 99.5 percent or higher should be afforded some evidentiary value," but clarified that finding that "sibling-to-sibling DNA test results reflecting any particular percentage probability will alone be sufficient to establish a claimed full sibling relationship." Rather, the results should be considered in conjunction with other evidence of the sibling relationship.
The full text of Matter of Ruzku can be found here: https://www.justice.gov/sites/default/files/pages/attachments/2016/03/29/3860.pdf