Prenatal diagnosis and molecular cytogenetic characterization of a de novo interstitial duplication of 11q (11q22.3→q23.3) associated with abnormal maternal serum biochemistry.

OBJECTIVE

To present prenatal diagnosis and molecular cytogenetic characterization of a de novo interstitial duplication of 11q (11q22.3→q23.3) in a pregnancy associated with abnormal maternal serum biochemistry.

CASE REPORT: A 33-year-old woman underwent amniocentesis in the second trimester because of abnormal maternal serum biochemistry. Her husband was 33 years old. At 17 weeks of gestation, the levels of α-fetoprotein (AFP), unconjugated estriol (uE3), total β-human chorionic gonadotropin (β-hCG), and inhibin A were 0.65 multiples of median (MoM), 0.61 MoM, 0.32 MoM, and 0.55 MoM, respectively, consistent with a positive trisomy 18 risk of 1/128. Results of amniocentesis revealed a small de novo interstitial duplication of 11q encompassing 11q23. An array comparative genomic hybridization analysis detected a 9.04-Mb duplication at chromosome 11q22.3-q23.3. A polymorphic DNA marker analysis was carried out, which determined a paternal origin of the duplication. Results of fluorescence in situ hybridization analysis showed a direct duplication of interstitial 11q. The karyotype was 46,XX,dup(11)(q22.3q23.3). Level II ultrasound was unremarkable. The parents opted to continue the pregnancy. A 2792-g female baby was delivered at 38 weeks of gestation. When examined at 10 months of age, the neonate was small for age and was abnormal in psychomotor development with apparent facial dysmorphisms, and small hands and feet.

CONCLUSION

Low levels of AFP, uE3, β-hCG, and inhibin A in the second trimester maternal serum biochemistry may be a distinctive prenatal feature in pregnancy with fetal chromosome 11q duplication.