Analysis of the clinical features of pericentric inversion of chromosome 9

OBJECTIVE: 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. METHODS: We studied the karyotypes from 4853 patients at a single center and retrospectively reviewed their clinical data. RESULTS: 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. CONCLUSIONS: 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.