Uniparental disomy and prenatal phenotype: Two case reports and review

• Published in: Medicine (Baltimore) Vol. 96; no. 45; p. e8474
• Main Authors: Li, Xiaofei, Liu, Yan, Yue, Song, Wang, Li, Zhang, Tiejuan, Guo, Cuixia, Hu, Wenjie, Kagan, Karl-Oliver, Wu, Qingqing
• Format: Journal Article
• Language: English
• Published: United States The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved 01.11.2017; Wolters Kluwer Health
• Subjects: Adult; Chromosomes, Human, Pair 14 - genetics; Clinical Case Report; Female; Humans; Phenotype; Polymorphism, Single Nucleotide; Pregnancy; Ultrasonography, Prenatal; Uniparental Disomy - diagnosis; Uniparental Disomy - genetics
• ISSN: 0025-7974; 1536-5964; 1536-5964
• DOI: 10.1097/MD.0000000000008474

Uniparental disomy (UPD) gives a description of the inheritance of both homologues of a chromosome pair from the same parent. The consequences of UPD depend on the specific chromosome/segment involved and its parental origin. We report prenatal phenotypes of 2 rare cases of UPD. The prenatal phenotype of case 1 included sonographic markers such as enlarged nuchal translucency (NT), absent nasal bone, short femur and humerus length, and several structural malformations involving Dandy-Walker malformation and congenital heart defects. The prenatal phenotype of Case 2 are sonographic markers, including enlarged NT, thickened nuchal fold, ascites, and polyhydramnios without apparent structural malformations. Conventional G-band karyotype appears normal in case 1, while it shows normal chromosomes with a small supernumerary marker chromosome (sSMC) in case 2. Genetic etiology was left unknown until single-nucleotide polymorphism-based array (SNP-array) was performed, and segmental paternal UPD 22 was identified in case 1 and segmental paternal UPD 14 was found in case 2. The parents of case 1 chose termination of pregnancy. The neonate of case 2 was born prematurely with a bellshaped small thorax and died within a day. UPD cases are rare and the phenotypes are different, which depend on the origin and affected chromosomal part. If a fetus shows multiple anomalies that cannot be attributed to a common aneuploidy or a genetic syndrome, or manifests some features possibly related to an UPD syndrome, such as detection of sSMC, SNP-array should be considered.