Study of two cases of prenatally detected small supernumerary marker chromosomes

Objective: To determine the origin of two prenatally detected small supernumerary marker chromosomes (sSMCs).

Methods: The sSMCs were analyzed with combined G-banding, C-banding, fluorescence in situ hybridization (FISH), and single nucleotide polymorphisms array (SNP-array) techniques.

Results: In case 1, G-banding analysis has identified a 47,XY,+mar karyotype. Affymetrix CytoScan 750K Array scan has suggested arr 15q11.2q12(22 770 421-26 604 587)?, while FISH analysis suggested 47,XN,+mar.ish i(15)(q12)(D15Z1+,SNRPN++,PML-). In case 2, G-banding analysis has suggested 46,X,+mar/46,XY, FISH analysis showed two SRY hybridization signals, indicating 46,X,i(Y)(p10)/46,XY.

Conclusions: Multiple techniques needed be applied for verification of the origin of sSMCs identified in prenatal diagnosis.