Study on isochromosomes: clinical experience from a tertiary referral center

This retrospective study analyzed 99 cases of isochromosomes, including 69 postnatal and 30 prenatal cases, to investigate chromosomal distribution, parental inheritance, and risk factors. Karyotyping and cytogenetic analyses identified that isochromosomes predominantly involved the X chromosome (86.7%, 86/99).

Among postnatal cases, 99.6% (68/69) exhibited sex chromosomal isochromosomes, with the most common karyotypes being 45,X/46,X,i(X)(q10) (40.5%) and 46,X,i(X)(q10) (39.1%). In prenatal cases, 63.3% (19/30) involved sex chromosomal isochromosomes, while 36.7% (11/30) involved autosomal isochromosomes. Parental chromosomal analysis for 69.0% (20/29) of fetuses showed normal results, suggesting that isochromosomes are predominantly de novo mutations.