Combined Application of Multiple Technologies in Prenatal Diagnosis of a Fetus with Mosaic Isodicentric Y Chromosome.

BACKGROUND

Isocentromere Y chromosome [idic(Y)] is a type of Y chromosome structural aberration, and patients have clinical manifestations such as Turner syndrome, unclear genitals, and male infertility.

METHODS

The patient underwent non-invasive prenatal genetic testing (NIPT), but failed three consecutive tests due to low fetal fraction (FF). Therefore, interventional amniocentesis was performed. G banding chromosome karyotyping analysis, copy number variation sequencing (CNV-seq), and fluorescence in situ hybridization (FISH) were used for prenatal diagnosis of fetal chromosomes.

RESULTS

The integrated cytogenomic approach (chromosomal karyotyping, CNV-seq and FISH) identified a complex mosaic karyotype: 45,X[23]/46,X,idic(Y)(q11.221)[20]/46,X,del(Y)(q11.221)[7]. The fetus was found to carry a new genetic variant in their family.

CONCLUSIONS

This study establishes a multi-platform diagnostic framework that overcomes the limitations of NIPT through 1) synergistic verification of mosaic abnormalities, and 2) precise breakpoint mapping at Yq11.221. It is crucial to combine various genetic techniques when studying mosaic idic(Y).