Application of Affymertrix SNP array and FISH analysis in identification of small supernumerary marker chromosome of r（4）4p13q13.3

Objective To identify the origin of small supernumerary marker chromosomes（sSMC） by Affymetrix SNP array and FISH analysis. Methods Chromosome karyotype in amniotic fluid and umbilical cord blood from a 38 years old pregnant woman who visited our hospital in July 2013 was detected by G-binding analysis. The fragments and origin of sSMC were identified by AffymetrixCytoScan 750 K array followed by FISH analysis using probe WSH/d4z1. Results G-binding analysis showed a chromosome karyotype of 46, XX15 /47, XX, +mar15 in amniotic fluid and a chromosome karyotype of 46, XX14 /47, XX, +mar16 in umbilical cord blood. AffymetrixCytoScan 750 K array showed a chromosome fragment of arr 4p13q13.3（41,593,201-72,130,692）X2-3 in amniotic fluid and a 30.537 Mb long chromosome fragment of 4p13-4q13.3 with a repeated mosaic in umbilical cord blood. FISH analysis showed that 28% interphase cells in umbilical cord blood displayed a trisomy. Conclusion Combining G banding analysis with FISH analysis and AffymetrixCytoScan 750 K array can accurately identify the origin and fragments of sSMC.