pregnancies had cytogenetic evaluation performed and the karyotypes were 47,XX,+18 and 46,XX, respectively. Cytogenetic evaluation of her current pregnancy showed an apparent duplication of material in chromosome band 8p23.1 (46,XY,dup(8)(p23.1) (Fig. 1). The amniotic fluid AFP and AchE results were within normal ranges. Cytogenetic evaluations were performed on parental peripheral blood specimens. The mother's metaphases showed a normal 46,XX karyotype. The father's results showed him to be carrying the same apparent duplication of the 8p23.1 region as observed in the fetus (Fig. 1). No other chromosome changes were found in the father. Chromosome 8 FISH painting (Coatasome 8, from Oncor) performed on the fetal and paternal cells showed the extra material on the chromosome 8s to be of chromosome 8 origin.
Evaluation of the karyotype from the previous normal pregnancy showed no variation involving chromosome 8. This suggests that there was no paternal translocation between the chromosome 8 homologues. Otherwise, this child would be hemizygous for material deleted from the inherited paternal chromosome 8. Phenotypic anomalies would be expected in this scenario. This evidence suggests this apparently duplicated euchromatic region of chromosome 8 should be considered a normal chromosome variation with no phenotypic effect.
Literature reveals 12 reported dup(8)(p23.1) cases with the dup(8) transmitted from parents to offspring in eight of those families (Barber et al., 1998; Joyce et al., 1996; Williams et al., 1996). A recent study (Barber et al., 1998) reviews these families. Using cytogenetic and molecular techniques, these researchers determined that the variation is a duplication of euchromatic chromosome material in the 8p23.1 region. This group also concludes the dup(8)(p23.1) is a cytogenetic anomaly with no clinical significance.
Therefore, this case gives additional proof of the prevalence and benign existence of this chromosome variation. Presentation of the dup(8)(23.1) in literature will help to reassure patients during prenatal counselling when this apparently normal variant is found.