A 35-year-old, gravida 7 para 3, woman was referred to Mackay Memorial Hospital at 21 gestational weeks for confirmation of a de novo interstitial deletion of chromosome 20p in a fetus. She had experienced three spontaneous abortions and had three healthy children. The woman and her husband were healthy, and there was no family history of congenital malformations. Detailed high-resolution ultrasound revealed a singleton fetus consistent with 21 gestational weeks and no gross abnormalities. Repeat amniocentesis was performed at 21 gestational weeks and 40 mL of amniotic fluid was aspired. Array-based comparative genomic hybridization (aCGH) was performed using uncultured amniocytes from 20 mL, whereas the remaining 20 mL was used for conventional cytogenetic analysis. Conventional cytogenetic analysis revealed an interstitial deletion at 20p ( Fig. 1). The parental karyotypes were normal. Oligonucleotide-based aCGH demonstrated partial monosomy 20p [arr cgh 20p12.1p11.21 (13,345,494–25,407,784 bp)×1] with a deletion of 12.1 Mb at chromosome 20p ( Fig. 2). The karyotype was 46,XX,del(20)(p11.21p12.1) de novo. The parents opted to terminate the pregnancy. A 536-g fetus with facial dysmorphism, hypertelorism, a flat nasal bridge, micrognathia, and low-set ears was delivered at 23 gestational weeks ( Fig. 3). The parental origin of the proximal deletion of 20p in the fetus was investigated by quantitative fluorescent polymerase chain reaction using polymorphic DNA markers. The deletion was of paternal origin ( Fig. 4).
Relation:
Taiwanese Journal of Obstetrics & Gynecology,50(2),249–252.
