Prenatal diagnosis of ring chromosome 13: a rare chromosomal aberration

Abstract

We report the case of a 24-year-old Japanese woman, gravida 2, para 1, who became pregnant spontaneously. At 24 weeks of gestation, her fetus was found to have various abnormalities, including holoprosencephaly, congenital heart disease and severe fetal growth restriction, and she was referred to our hospital. From these findings, the fetus was suspected of having a chromosomal aberration, in particular, trisomy 13, and after genetic counseling, amniocentesis for chromosomal analysis was performed. Although the results of fluorescent in situ hybridization (FISH) analysis showed no numeric abnormalities, G-banding analysis revealed a ring chromosome 13; 46, XX, r (13) (p13q32). At 41 weeks of gestation, she delivered a female baby weighing 2240 g with good condition. The respiratory status of the neonate was stable, and she was discharged 30 days after birth. Ring chromosomes are rare chromosomal aberrations, and obstetricians should recognize that ring chromosomes cannot be detected solely by FISH analysis and require G-banding analysis and that information on the ring breakpoint is needed to counsel the parents regarding the fetal and neonatal prognosis.