Breakpoint regions of an RHD-CE(4-9)-D allele and a rare JK allele in a Pacific Islander individual.

We determined the 2 breakpoint regions of his RHD-CE(4-9)-D hybrid allele, which was likely distinct from the 2 previously published hybrid alleles due to the differences in the linked RHCE allele. His RHD variant was shown to express the C antigen. An SLC14A1 substitution was underlying his unexpected Jk-negative phenotype. In a quality improvement project, we resolved 8 samples with similarly discrepant results between Jk serology and red cell genotyping.