Analysis of the clinical features of pericentric inversion of chromosome 9

The pericentric inversion of chromosome 9 (inv9) is one of the most common structural balanced chromosomal variations, and it is considered to be a normal population variant. The aim of this study was to re-evaluate the clinical impact of patients with inv9.

We studied the karyotypes from 4853 patients at a single center and retrospectively reviewed their clinical data.

There were 67 inv9 patients among 2988 adults, and 62 of them showed different clinical features, including male and female infertility, oligoasthenozoospermia, and azoospermia. Thirty-one cases of inv9 were found in 1865 fetuses, including two cases in chorionic villus (6.90%) and 29 in amniotic fluid (1.67%), but there were no cases in umbilical cord blood. The rates of fetal phenotype abnormal and adverse pregnancy outcome with inv9 in the chorionic villus were 100.00% (2/2), while only 17.24% (5/29) in the amniotic fluid showed abnormalities, among which 60.00% (3/5) had adverse pregnancy outcomes.

Although there is no clear evidence that inv9 is pathogenic, the genetic counseling on inv9 in early pregnancy and adults needs to be given more attention.