UNIPARENTAL MATERNAL DISOMY-6 IN A RENAL-TRANSPLANT PATIENT

HLA analysis of the family of a renal transplant patient revealed an e xtremely rare condition. On repeated typings the only demonstrable HLA antigens shown in the propositus were from the maternal haplotype, HL A-A11,-B46,-Cw1,-DR14,-DQ1. No paternal antigens could be demonstrated either by serologic or by DNA-typing methods. A paternity investigati on was carried our to exclude the possibility of the legal father not being the biological father. The results of this investigation showed a paternity index I = >20000 and a fatherhood probability W = >99.995% . Karyotyping of the patient showed two normal chromosomes 6 and no ot her chromosomal abnormalities. Maternal isodisomy Tvas demonstrated fr om the analysis of polymorphic DNA markers, involving the short as wel l as the long arm of chromosome G. These data are consistent: with thi s patient having the first uniparental maternal disomy G reported (inh eritance of two identical chromosome G haplotypes from the mother and none from the father).