Complete trisomy 17p syndrome in a girl with der(14)t(14;17)(p11.2;p11.2)

Road to a rare diagnosis: Description of novel unbalanced translocation causing partial trisomy 17p

Trisomy 17 is a rare chromosomal disorder. Existing literature on the topic is limited and mostly refer to mosaic Trisomy 17 cases. Our report summarizes the 70‐day clinical course of a late preterm neonate with partial Trisomy 17p karyotype 46,XY,der(14)t(14;17)(p11.1;p11.2) dpat. Trisomy 17 due to unbalanced translocation is rare, and our case elaborates the clinical presentation with intestinal malfunction without any anatomical pathology and urethral diverticulum and the ethical dilemma in decision‐making. The male proband was born at 35 weeks with antenatal findings of multiple neurological and other abnormalities such as cystic hygroma, absent corpus collosum, high riding third ventricle, absent cavum septum pellucidum, indented occiput, absent ductus venous, and intrauterine growth restriction. The postnatal findings included significant facial dysmorphisms with short palpebral fissures, hypertelorism, low set ears, micrognathia, hirsutism, and single palmar creases, central hypotonia, and hyperreflexia of upper limbs bilaterally. Genital‐urinary assessment revealed a urinary diverticulum and significantly underdeveloped scrotum with undescended testes. Infant had excessive irritability and resistance to sleep despite increasing doses of analgesia and sedation, and persistent respiratory and feeding difficulties. Enteral nutrition could not be established due to profuse and persistent diarrhea, necessitating use of total parenteral nutrition. Microarray assay exhibited a pathogenic copy number gain of approximately 21.4 Mb of chromosome region 17p13.3p11.2. Follow‐up chromosome analysis and FISH revealed an abnormal male karyotype with a derivative chromosome 14, resulting from an unbalanced translocation between the short arm of one chromosome 14 and the short arm of one chromosome 17, effectively resulting in trisomy 17p11.2. It was derived from a paternal balanced t(14;17)(p11.1;p11.2) as shown by chromosome analysis and FISH studies. The rarity of this chromosomal disorder contributed to difficulty with prognosis and led to bioethical dilemma regarding life‐sustaining measures and quality of life. Through shared decision‐making processes and in consideration of poor prognosis, parents decided to withdraw life‐sustaining care and the proband died at postnatal day of life 70.

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

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.

Molecular characterization of near-complete trisomy 17p syndrome from inverted duplication in association with cryptic deletion of 17pter

Trisomy of the short arm of chromosome 17 (T17P) is a genomic disorder presenting with growth retardation, motor and mental retardation and constitutional physical anomalies including congenital heart defects. Here we report a case of near-complete T17P of which the genomic dosage aberrations were delineated by chromosomal microarray along with conventional diagnostic modalities. A 9-year-old Korean boy was admitted because of esophageal obstruction. He showed clinical manifestations of T17P, along with atypical features of scoliosis, corpus callosum agenesis, and seizure. Chromosome analyses revealed an inverted duplication of the chromosomal segment between 17p11.2 and 17p13.3. Chromosomal microarray revealed a duplication of the most of the short arm of chromosome 17 (size ~19.09 Mb) along with a cryptic deletion of a small segment of 17p terminal end (17pter) (~261 Kb). This is the first report of molecular characterization of near-complete T17P from inverted duplication in association with 17pter microdeletion. The fine delineation of the extent of genomic aberration by SNP-based microarray could help us better understand the molecular mechanism and genotype-phenotype correlations in T17P syndrome.

Effects of deletion and duplication in a patient with a 46,XX,der(7)t(7;17)(q36;p13)mat karyotype

Exact breakpoint determination by DNA-array has dramatically improved the analysis of genotype-phenotype correlations in chromosome aberrations. It allows a more exact definition of the most relevant genes and particularly their isolated or combined impact on the phenotype in an unbalanced state. Here, we report on a 21-year-old female with severe growth retardation, severe intellectual disability, hypoplasia of the corpus callosum, unilateral sacral hypoplasia, tethered cord, various minor facial dysmorphisms, and a telomeric deletion of about 4.4 Mb in 7q36.2->qter combined with a telomeric duplication of about 8 Mb in 17pter->p13.1. Fine mapping was achieved with the Illumina® Infinium HumanOmni1-Quad v1.0 BeadChip. Most of the major clinical features correspond to the well-known effects of haploinsufficiency of the MNX1 and SHH genes. In addition, review of the literature suggests an association of the 17p duplication with specific facial dysmorphic features and skeletal anomalies, but also an aggravating effect of the duplication-deletion for severe growth retardation as well as sacral and corpus callosum hypoplasia by one or more genes located on the proximal half of the segmental 17p duplication could be elaborated by comparison with other patients from the literature carrying either the deletion or the duplication found in our patient.

A microduplication on chromosome 17p13.1p13.3 including the PAFAH1B1 (LIS1) gene

Recently, three children with a microduplication in 17p13 including the PAFAH1B1 gene that encodes LIS1 were reported. LIS1 overexpression has earlier been shown to affect brain development by causing migrational defects and reductions in brain volume [Bi et al., 2009]. Here, we report an additional patient with a microduplication on chromosome 17p13.1p13.3 including the PAFAH1B1 gene, that was inserted into the long arm of chromosome 4. The patient had psychomotor and growth retardation, dysmorphic features, small ventricular septal defect (VSD), and immunoglobulin abnormality. Only subtle abnormalities in brain MRI scan were seen. Interestingly, the facial features of our patient closely resemble those previously reported in 17p trisomy patients.

Cystic Dilation of the Aqueductus Sylvii in Case of Trisomy 17p11.2-pter with the Deletion of the Terminal Portion of the Chromosome 6

Since the 1970s, about 30 cases of partial or complete trisomy 17p have been presented in the literature. Partial trisomies of the short arm of chromosome 17 are somewhat more common, but complete trisomy is quite rare. Most of these cases were described in infants and newborns; and to our knowledge only 3 cases of trisomy 17p have been detected intrauterine. Phenotypic features of trisomy 17p in fetuses are intrauterine growth retardation, ventriculomegaly, cleft lip and cleft palate, micrognathia, horseshoe kidneys, single umbilical artery, and congenital heart defects. The sonographic and foetopathologic findings of a pregnancy trisomy 17p11.2-pter with the deletion of the terminal portion of the chromosome 6 due to paternal balanced translocation are described in this case report.

Increased LIS1 expression affects human and mouse brain development

Deletions of the PAFAH1B1 gene (encoding LIS1) in 17p13.3 result in isolated lissencephaly sequence, and extended deletions including the YWHAE gene (encoding 14-3-3epsilon) cause Miller-Dieker syndrome. We identified seven unrelated individuals with submicroscopic duplication in 17p13.3 involving the PAFAH1B1 and/or YWHAE genes, and using a 'reverse genomics' approach, characterized the clinical consequences of these duplications. Increased PAFAH1B1 dosage causes mild brain structural abnormalities, moderate to severe developmental delay and failure to thrive. Duplication of YWHAE and surrounding genes increases the risk for macrosomia, mild developmental delay and pervasive developmental disorder, and results in shared facial dysmorphologies. Transgenic mice conditionally overexpressing LIS1 in the developing brain showed a decrease in brain size, an increase in apoptotic cells and a distorted cellular organization in the ventricular zone, including reduced cellular polarity but preserved cortical cell layer identity. Collectively, our results show that an increase in LIS1 expression in the developing brain results in brain abnormalities in mice and humans.

Report of a child with a complete de novo 17p duplication localized to the terminal region of the long arm of chromosome 17

We report the second case of a child with trisomy of the entire short arm of chromosome 17 secondary to a de novo duplication. Trisomy 17p in this patient resulted from a duplication, localized to the distal region of the long arm of the same chromosome, an abnormality not previously described. This cytogenetic abnormality was confirmed using whole chromosome paint, subtelomeric and Smith-Magenis probes by fluorescence in situ hybridization (FISH) analysis. The child presented with phenotypic features previously described in trisomy 17p, including some specific facial dysmorphia, microcephaly, growth retardation, hypotonia, short webbed neck, congenital heart defect, minor abnormalities of the hands, agenesis of the corpus callosum and abnormalities of the iris. Iris alterations and defects involving the left side of heart and the aorta also may represent truly clinical hallmarks of this cytogenetic abnormality. In conclusion, this cytogenetic anomaly seems to represent a severe malformation entity with a poor prognosis and a recognizable clinical pattern that justifies the use of the term "17p trisomy syndrome" suggested previously by other authors.