Genetic analysis of a fetus with mosaicism of structural aberration of Y chromosome

Objective: To carry out genetic analysis and parental tracing for a fetus with an inconclusive chromosomal karyotype.

Methods: The fetus and its parents were subjected to combined chromosomal karyotyping, chromosomal microarray analysis (CMA), fluorescence in situ hybridization (FISH) and multiplex PCR testing for Y chromosome microdeletions.

Results: The fetus was found to have a karyotype of 45,X[18]/46,X,+mar[72]. CMA revealed that the fetus has carried a 2.6 Mb duplication at Yp11.32p11.31 and a 44.5 Mb deletion at Yq11.21q12. Interphase FISH of amniocytes confirmed the chromosomal mosaicism in the fetus, which has derived from Y chromosome. Multiplex PCR revealed deletion of AZFb and AZFc regions on the Y chromosome. No karyotypic abnormality was found with either parent at 400-band level.

Conclusions: Combined genetic analysis has delineated the aberrant karyotype in the fetus, which has facilitated prediction of its clinical phenotype and genetic counseling.