Blood chimerism in twins.

Chimerism is a phenomenon in which an individual has cells with different genetic content from different zygotes. In dizygotic twins (DTs), chimerism is believed to occur through placental anastomoses that enable the bidirectional exchange of hematopoietic stem cells. Little is still known about chimerism frequency in twins, but several studies have shown a relation between chimerism and some conditions such as autism, Alzheimer's disease, and a group of autoimmune diseases such as Sjögren syndrome, systemic lupus erythematosus, and systemic sclerosis.

Molecular matching of red blood cells is superior to serological matching in sickle cell disease patients.

Objective: To evaluate the usefulness of DNA methods to provide a means to precisely genotypically match donor blood units for the antigen-negative type of 35 sickle cell disease patients.

Methods: Red blood cell units were investigated for ABO, D, C, c, E, e, K, Fy(a), Fy(b), Jk(a), Jk(b), S, s, Di(a) and RH variants by performing a molecular array (Human Erythrocyte Antigen BeadChip(TM), BioArray Solutions), polymerase chain reaction followed by restriction fragment length polymorphism analysis and sequencing of patient samples and donor units that had been serologically matched based on the ABO, Rh and K phenotypes and the presence of antibodies.

Results: Matches for 21 of 35 sickle cell disease patients presented discrepancies or mismatches for multiple antigens between the genotype profile and the antigen profile of their serologically-matched blood units.