Is cytogenetic diagnosis of 46,XX karyotype spontaneous abortion specimens erroneous? Fluorescence in situ hybridization as a confirmatory technique.

AIM: Performing the standard cytogenetic technique on spontaneous abortion material is still a valuable tool, but finding a normal 46,XX karyotype can confuse investigators and lead to a problem in diagnosis. This is mainly because it is possible for the female or male conceptus to retain contaminating maternal cells. To address this possibility, we used fluorescence in situ hybridization technique (FISH). X (DXZ1: p11.1-q11.1 region) and Y (DYZ3: p11.1-q11.1 region) chromosome alpha-satellite probes were employed to confirm the karyotypes previously diagnosed as 46,XX by our cytogenetic laboratory, or to verify the occurrence of 'Y chromosome component'.

METHODS

Besides conventional long-term tissue cultures and G-bands by trypsin using Giemsa (GTG) bandings, FISH analyses were also performed.

RESULTS

A total of 134 spontaneous abortion specimens (singleton gestations) were referred for cytogenetic evaluation, of which 125 specimens were successfully karyotyped. Of these, 20.8% (26/125) had chromosome aberrations; 88.5% (23/26) of these aberrations were numerical and 11.5% (3/26) were structural. The most prevalent numerical anomalies were trisomies 15, 16 and 21, tetraploidies, triploidies and monosomy X. FISH results were obtained for 45 out of 92 cases with 46,XX, of which 2 (4.4%) showed XY signals.

CONCLUSIONS

For accurate cytogenetic evaluation of spontaneous abortion materials, an additional technique such as FISH is required in order to confirm the cytogenetic results or to provide an estimate of the error rate in the analysis of miscarriages.