The originating haplogroups of the O Rh negative blood which are proven lines, meaning families who have kept records of their clans, and know they are Bretons, Gaels & Picts are as follows:
Y DNA Haplogroups I2b1 now known as (I2a2) & J2. As as well as other lines in the I and J haplogroup, and mtDNA haplogroups I2, H and U.
However, it is important to realise that blood type is NOT passed through Y DNA or mtDNA, it is passed through Autosomal DNA.
Because the genes that cause Rh negative blood are recessive, anyone who has bred with someone from one of our families in the past, could end up with Rh negative blood, and their DNA groups will not be that of the bloodline families.
Someone with AB+ blood could also have some of our other recessive traits if someone in their family history bred with one of our bloodline, so they might for instance have red hair and blue eyes.
People who don't understand genetics and DNA run about claiming their DNA line is the origin of Rh negative blood, without realising that they only have Rh negative blood because someone in their family at one time bred with one of the bloodline families, who are the origin of this blood. If they were one of the bloodline families, they would already know about it.
R1b Y DNA is hybrid DNA, and NOT the origins of Rh negative blood.