Objective: To explore the clinical significance of a prenatal case with two small supernumerary marker chromosomes (sSMC) through identification of their origins.
Methods: G-banding chromosomal karyotyping analysis were carried out on fetal amniotic fluid sample and peripheral blood samples from both patients. Fluorescence in situ hybridization (FISH) and single nucleotide polymorphism-array (SNP-array) were used to analyze the component and size of the sSMCs.
Results: The karyotype of the fetus was determined as 47, XX, +mar[53]/48, XX, +2 mar[31]/46, XX[14]. SNP-array has revealed four copies of chromosome 2q11.1q11.2 with a size of 2.6 Mb and three copies of 10p11.23q11.23 with a size of 20.6 Mb. The results was confirmed by FISH.
Conclusion: A rare chromosomal abnormality with two sSMCs was identified by combined karyotype analysis, SNP-array and FISH, which provided valuable information for prenatal diagnosis.