Objective: To analyze a case of supernumerary marker chromosome (SMC) with combined genetic techniques and explore its correlation with the clinical phenotype.
Methods: The SMC was analyzed with G-banded karyotyping, multiplex ligation dependent probe amplification (MLPA), fluorescence in situ hybridization (FISH), and single nucleotide polymorphism array (SNP-array).
Results: G-banding analysis indicated that the patient has a karyotype of 47,XX,+mar. MLPA showed that there were duplications of proximal 15q. FISH assay using D15Z4 probes indicated that the SMC was a pseudodicentric chromosome derived from chromosome 15. And SNP-array revealed that there were two extra copies of 15q11-13 region spanning from locus 20 161 372 to 29 071 810.
Conclusion: The duplication of Prader-Willi/Angelman syndrome critical region probably underlies the abnormal phenotype of the inv dup(15) case with a BP3:BP3 rearrangement.