Ultrasonographic findings and prenatal diagnosis of complete trisomy 17p syndrome: A case report and review of the literature

Abstract Background Trisomy of the short arm of chromosome 17 is a rare genomic disorder. The clinical features of complete trisomy 17p syndrome have been described. Most cases of this syndrome have been found in infants and children, but only a few cases were found by ultrasound in the prenatal period. Methods We report a case of complete trisomy 17p syndrome, which was inherited from paternal balanced translocation t(15;17)(q11.2;q11.2). A pregnant woman underwent an ultrasound examination at 24 weeks of gestation. Amniotic fluid was collected by amniocentesis. Cytogenetic and single nucleotide polymorphism array analyses were performed. We further reviewed the relationship between duplication regions and the clinical phenotype. Results Ultrasonographic evaluation showed intrauterine growth retardation and a right choroid plexus cyst, but the gallbladder was not observed. The fetal karyotype was 46,XX,der(17)t(15;17)(q11.2;q11.2)pat. The father's karyotype was 46,XY,t(15;17)(q11.2;q11.2). The single nucleotide polymorphism array results showed arr[GRCh37] 17p13.3q11.1(525‐25309337)×3, which indicated a 25.309‐Mb duplication. Conclusion Complete trisomy 17p syndrome shows severe malformations. Intrauterine growth retardation is the most typical manifestation of this syndrome as shown by ultrasonography in the second trimester of pregnancy. The genotype‐phenotype relationships of complete trisomy 17p syndrome are not completely consistent. To further determine these relationships, additional cases are necessary to provide more information from ultrasonographic findings during pregnancy.


| INTRODUC TI ON
Trisomy of the short arm of chromosome 17 is a rare genomic disorder. 1 The clinical features of complete trisomy 17p syndrome have been previously described. [2][3][4] These mainly include prenatal and postnatal growth retardation, craniofacial anomalies, short webbed neck, hypotonia, cardiac malformations, joint contractures, abnormality of the iris, and varying degrees of hearing loss. Most carriers have been reported in infants and childhood, but only a few cases have been described by ultrasound in the prenatal period. 1,2,[5][6][7][8] Therefore, further studies are required to determine the genotype-phenotype correlation underlying these chromosomal rearrangements.
We report a new case of complete trisomy 17p syndrome, which was inherited from a paternal balanced translocation t(15;17) (q11.2;q11.2). Combining our results of the current case with previously reported literature, we further review the relationship between duplication regions and phenotypes.

| MATERIAL S AND ME THODS
This study was approved by the Ethics Committee of the First Hospital of Jilin University (No. 2020-378). Written informed consent was obtained from the patient for publication of this case report.

| Cytogenetic analysis
Amniotic fluid was collected by amniocentesis at 24 weeks of gestation. Fetal cells were collected by 15-mL centrifuge tubes for culture. Peripheral blood of the parents was collected by a standard vacuum extraction blood collecting system, which contained EDTA and heparin. Routine sample preparation and chromosome analysis were performed using G-banding techniques at a resolution of 300-400 banding in accordance with laboratory standard protocols. Twenty metaphases were counted and at least six karyotypes were analyzed. The karyotypes were described according to the International System for Human Cytogenetic Nomenclature (ISCN 2016).
Human chromosome 17 is well known by its duplication structure and complex rearrangement. 9 Several frequent, unbalanced rearrangements are associated with 17p, and these contain some region-specific low-copy repeat sequences. Structural rearrangement of low-copy repeat sequences in 17p leads to genomic disorders. 10 The YWHAE gene is closely related to autism, developmental delay, learning delay, and other disorders. The PAFAH1B1 gene is associated with developmental delay, microcephaly, small body size, and other brain malformations. 15 On the basis of these genotype-phenotype relationships, the clinical manifestation of complete trisomy 17p may be more complex than originally thought.
Partial or complete trisomy of chromosome 17p is relatively rare.
The first report of trisomy 17p was described by Latta et al in 1974. 16 Since that time, more cases have been reported as described below.

| CON CLUS ION
Complete trisomy 17p syndrome has severe malformations.
Intrauterine growth retardation is the most typical manifestation of trisomy 17p as shown by ultrasonography in the second trimester of pregnancy. According to the current literature, the genotypephenotype relationships of complete trisomy 17p syndrome are not completely consistent. To further delineate these relationships, additional cases are required to provide more information by ultrasonographic findings during pregnancy.

ACK N OWLED G M ENT
We thank Ellen Knapp, PhD, from Liwen Bianji, Edanz Group China (www.liwen bianji.cn/ac), for editing the English text of a draft of this manuscript.