Prenatal determination of genotypes Kell and Cellano in at-risk pregnancies.

W C Spence
A Maddalena
D B Demers
D P Bick


OBJECTIVE: To evaluate the accuracy of a DNA-based testing methodology in determining the KEL1 and KEL2 (Kell and Cellano) genotype of fetuses at risk for Kell or Cellano hemolytic disease.

STUDY DESIGN: DNA was extracted from chorionic villus samples (CVS) or amniotic fluid (AF) cells, a portion of the Kell gene was amplified, the amplified product was cut with a restriction enzyme that recognizes the KEL1 nucleotide substitution, and the digested product was run on a polyacrylamide gel to separate the fragments. This analysis was routinely run on uncultured cells to provide rapid results. Testing of parental DNA was performed in conjunction with fetal analysis to ensure that their alleles were detectable with this DNA test.

RESULTS: We determined the fetal KEL1 and KEL2 genotype in 1 CVS and 65 AF specimens. Forty-eight of them were determined to be KEL2, 17 were KEL1/2, and 1 was KEL1. Among the fetuses born to date, follow-up information was available on 14 of them, 11 KEL2 and 3 KEL1/2. In all 14 there was complete correlation between the DNA analysis and the serotype or clinical course.

CONCLUSION: Determination of the fetal KEL1 and KEL2 genotype using this DNA-based method provides accurate and timely information that can aid the prenatal care of women sensitized to these Kell antigens.