Figure 4. Preimplantation HLA matching for Diamond-Blackfan anemia (DBA). (Upper panel) Determination of the different haplotypes from father, mother and affected child (lower panel-left side, black square) by segregation analysis of the alleles obtained after STR genotyping of the HLA region. Informative STR markers used are ordered from telomere (top) to centromere (bottom). Paternally and maternally derived HLA haplotypes, matched to the affected child, are shown in boldface. Examples of different results of HLA haplotyping from biopsied blastomeres are shown in the lower panel. Embryos 5 has no paternal chromosome present (monosomy 6); embryo 13 shows an extra maternal chromosome (trisomy 6); embryo 1 shows a single recombination occurrence in maternal haplotypes between the alleles of the markers D6S105 and MIB (square); in embryo 6, initially appearing to be HLA matched with the affected sibling, a double recombination event was observed between the markers D6S1683 and D6S265 (square). Embryos 7 and 19 were diagnosed as HLA matched and were transferred. ET = Embryo Transfer.