First-trimester application of expanded non-invasive prenatal testing in the genetic investigation of fetal 1p36 deletion syndrome associated with a familial unbalanced reciprocal translocation of 46,XX,der(1)t(1;2) (p36.2;q37.3)dmat

Abstract

Objective: We present first-trimester application of expanded non-invasive prenatal testing (NIPT) in the genetic investigation of fetal 1p36 deletion syndrome associated with a familial unbalanced reciprocal translocation of 46,XX,der(1)t(1;2) (p36.2;q37.3)dmat. Case report: A 37-year-old, gravida 2, para 0, woman underwent expanded NIPT at 13 weeks of gestation because of advanced maternal age and the fear of complications of invasive procedures of prenatal diagnosis. She had experienced one spontaneous abortion. The pregnancy was conceived by in vitro fertilization and embryo transfer (IVF-ET) because of tubal occlusion. NIPT was positive for 1p36 deletion. At 17 weeks of gestation, she underwent amniocentesis but intrauterine fetal death occurred after amniocentesis and the pregnancy was terminated. Amniocentesis revealed a derivative chromosome 1 with an aberrant short arm terminal segment of chromosome 1. Subsequent cytogenetic analysis of parental bloods showed a karyotype of 46,XY in the father and a karyotype of 46,XX,t(1;2) (p36.2;q37.3) in the mother. The karyotype of amniocytes was 46,XX,der(1)t(1;2) (p36.2;q37.3)dmat, consistent with partial monosomy 1p (1p36.2→pter) and partial trisomy 2q (2q37.3→qter). Array comparative genomic hybridization (aCGH) analysis on the DNA extracted from cultured amniocytes revealed the result of arr 1p36.33p36.22 (852,863–11,303,452) × 1.0 and arr 2q37.3 (242,785,405–243,068,396) × 3.0 [GRCh 37] with a 10.451-Mb deletion of 1p36.33-p36.22 encompassing 116 OMIM genes including RERE and a 283-kb duplication of 2q37.3 encompassing one OMIM gene of PDCD1. Conclusion: Expanded NIPT has the advantage of early detection of familial unbalanced reciprocal translocation in the fetus.

Keywords

• 1p36 deletion
• Expanded NIPT
• Partial monosomy 1p (1p36.2→pter)
• Partial trisomy 2q (2q37.3→qter)
• Translocation