Prenatal diagnosis of a 5.44-Mb de novo 22q13.31q13.33 deletion encompassing SHANK3 associated with mosaicism for r(22)(p11.2q11.31) and monosomy 22 in a fetus with severe right hydronephrosis and hydroureter on ultrasound and determination of a maternal origin of the deletion and r(22) by quantitative fluorescent polymerase chain reaction

Abstract

Objective: We present prenatal diagnosis of a de novo 22q13.3 deletion in a fetus associated with mosaic r(22) and abnormalities on prenatal ultrasound. Case Report: A 32-year-old, primigravid woman was referred for amniocentesis at 30 weeks of gestation because of abnormalities on prenatal ultrasound. Prenatal ultrasound at 22 weeks of gestation revealed right hydronephrosis and hydroureter. Amniocentesis revealed a karyotype of 46,XX,r(22) in 21/21 colonies of cultured amniocytes. Simultaneous array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed the result of arr [GRCh37] 22q13.31q13.33 (45,736,280–51,178,264) × 1 with a 5.44-Mb 22q13.31q13.33 deletion encompassing SHANK3. Therefore, the r(22) was r(22)(p11.2q13.31). Level II ultrasound at 30 weeks of gestation revealed severe right hydronephrosis and hydroureter. The pregnancy was subsequently terminated, and a malformed female fetus was delivered with facial dysmorphism. Postnatal aCGH analysis on the DNA extracted from umbilical cord confirmed the prenatal diagnosis of 22q13.3 deletion and r(22), and quantitative fluorescent polymerase chain reaction (QF-PCR) analysis on the DNA extracted from umbilical cord and parental bloods determined a maternal origin of the 22q13.3 deletion. The umbilical cord had a karyotype of 46,XX,r(22)(p11.2q13.31)[34]/45,XX,-22[6]. The parental karyotypes were normal, and the parents did not have such a deletion. Conclusion: Fetuses with 22q13.3 deletion may present unilateral hydronephrosis and hydroureter on fetal ultrasound.

Keywords

• 22q13 deletion syndrome
• Mosaicism
• Phelan-McDermid syndrome
• r(22)
• SHANK3