Partial trisomy 16q21➔qter due to an unbalanced segregation of a maternally inherited balanced translocation 46,XX,t(15;16)(p13;q21): a case report and review of literature

A novel case of 16q22.3 duplication syndrome in a child with overgrowth: case report and literature review

BACKGROUND

Distal chromosome 16 duplication syndrome (also known as 16q partial trisomy) is a very rare genetic disorder recently described in few clinical reports. 16q trisomy is generally associated with a multisystemic phenotype including intrauterine growth restriction (IUGR), brain and cardiac defects, intellectual disability (ID) and an increased risk of both prenatal and postnatal lethality. Smaller copy number variants (CNV) within the 16q region create partial trisomies, which occur less frequently than full trisomy 16q.

CASE PRESENTATION

We present the clinical case of a 12-years-old male with a 16q22.3q24.1 de novo heterozygous duplication whose phenotype was characterized by ID, facial dysmorphisms, stature and weight overgrowth. To date, only five other cases of this syndrome have been reported in scientific literature, and none of them comprised overgrowth.

CONCLUSIONS

Our case report highlights the great heterogeneity in clinical manifestations and provides new evidence for better defining the phenotypic picture for smaller 16q distal CNVs, suggesting unusual features.

Clinical Features of de novo Pure 16q21q24.1 Chromosome Duplication

Pure partial duplications of the long arm of chromosome 16 are rare and few cases are described with delineation by chromosomal microarray. Data about clinical abnormalities of pure partial 16q duplications are incomplete because many individuals die during the perinatal period. We describe the clinical features of a 47-month-old Brazilian girl with 16q21q24.1 duplication. To the best of our knowledge, she is the first person with this specific chromosome segment duplication, and we compare her phenotype with the only reported individual alive with intermediate-distal pure 16q duplication.

A rare description of pure partial trisomy of 16q12.2q24.3 and review of the literature

Trisomy 16 is the most common autosomal trisomy in humans, which is almost uniformly embryonic lethal. Partial trisomy 16 including a segment of the long arm of chromosome 16 is occasionally compatible with life and has been associated with severe congenital defects, growth retardation, and early lethality. Segmental trisomy of 16q is usually described concomitantly with partial monosomy of another chromosome, often resulting from a parental balanced translocation. Pure partial chromosome 16q trisomy is exceedingly rare. About nine children with 16q12→qter and 16q13→qter duplication have been reported in the literature, almost all described with monosomy of a second chromosome, and highlighting very few long-term survivors. A single individual with pure partial distal 16q12.1q23.3 duplication has been reported in an infant, underscoring complexities of genetic counseling and management, especially in view of life-limiting congenital anomalies in rare survivors. Here, we present a 12-month-old child with pure 16q12.2q24.3 trisomy, having continued morbidity related to pulmonary hypertension and chronic lung disease. The features of intrauterine growth retardation, facial dysmorphism, hypotonia, congenital heart defect, distal contractures, urogenital abnormalities, and hearing loss support the association with 16q partial trisomy, as in previous studies. This report expands our current understanding related to the survival of infants with large segmental aneusomy of the long arm of chromosome 16.

Partial trisomy 16q and partial monosomy 7p of a fetus derivated from paternal balanced translocation: A case report

INTRODUCTION

Subchromosomal deletions and duplications could currently be detected by noninvasive preliminary screening (NIPS). However, NIPS is a screening test that requires further diagnosis. Here we report a fetus with an autosomal abnormality revealed by NIPS and conventional karyotype combined with copy number variations sequencing (CNV-seq) confirmed the fetus with an unbalanced translocation.

PATIENT CONCERN

This was the fourth pregnancy of a 30-year-old woman who underwent 2 spontaneous abortions and gave birth to a child with a normal phenotype. The woman and her husband were healthy and nonconsanguineous. NIPS indicated a repeat of about 19-Mb fragment at the region of 16q22.1-q22.4 at 17-week gestation.

DIAGNOSES

The combination of traditional karyotype and CNV-seq could better locate the abnormal chromosomal region and further identify the source of fetal chromosomal abnormalities. Simultaneously, we evaluated the fetal morphology by ultrasound examination. The karyotype of the fetus was 46,XX,der(7)t(7;16)(p22;q23) and CNV-seq results showed an approximately 20.96-Mb duplication in 16q22.1-q24.3 (69200001-90160000) and an approximately 3.86-Mb deletion in 7p22.3-p22.2 (40001-3900000). Prenatal ultrasound revealed the fetal micrognathia. The paternal karyotype was 46,XY, t (7;16) (p22;q23), while the maternal was normal. The fetus inherited an abnormal chromosome 7 from its father.

INTERVENTIONS

No treatment for the fetus.

OUTCOMES

Pregnancy was terminated.

CONCLUSIONS

To our knowledge, the occurrence of de novo partial trisomy 16q (16q22.1-qter) and partial monosomy 7p (7p22.2-pter) has not previously been reported up to now. Here, we present the perinatal findings of such a case and a review of the literatures. CNV-seq combined with karyotype is a useful tool for chromosomal abnormalities indicated by NIPS.

Mosaic Trisomy 16 Associated with Left Lung Agenesis, Abnormal Left Arm, and Right Pulmonary Artery Stenosis: Expanding the Phenotype and Review of the Literature

Trisomy 16 is the most common autosomal trisomy found in spontaneous abortions with mosaic versions seen in survivors. However, surviving children have multiple congenital defects and are at risk of growth and developmental delay. We report an additional case of mosaic trisomy 16 diagnosed by amniocentesis and confirmed after birth. Our patient is the first documented case of living mosaic trisomy 16 with the malformation constellation of lung agenesis, left pulmonary artery agenesis, congenital heart defects, and ipsilateral radial ray and limb abnormalities, expanding the phenotype of this rare condition. Additionally, this individual's unique combination of lung and cardiac defects caused morbidities that were challenging to manage and complicated family counseling as well.

Partial Trisomy 16q21-q24.3 with Novel Cardiac Manifestation of Left Ventricular Noncompaction Cardiomyopathy: A Case Report

Partial trisomy 16q is most often a consequence of malsegregation from a balanced parental translocation involving chromosome 16q. It is characterized by nonspecific craniofacial dysmorphic features, hypotonia, developmental delay, psychomotor retardation, and systemic manifestations of cardiac defect, renal abnormalities, and lung abnormalities. The survival of these patients depends upon the extent and severity of the organs involved. The present literature was replete with cases of partial trisomy 16q having structural cardiac defects. However, in the present report we described a novel finding of myocardial disease in the form of left ventricular noncompaction (LVNC) cardiomyopathy associated with this genetic condition.

Molecular cytogenetic characterization of partial monosomy 2p and trisomy 16q in a newborn: A case report

Trisomy 16q is a rare disorder with severe abnormalities, which always leads to early postnatal mortality. It usually results from a parental translocation, exhibiting 16q duplication associated with another chromosomal deletion. The present study reports on the clinical presentation and molecular cytogenetic results of a small-for-gestational-age infant, consisting of partial trisomy 16q21→qter and monosomy 2p25.3→pter. The proband presented with moderately low birthweight, small anterior fontanelles, prominent forehead, low hairline, telecanthus, flat nasal bridge, choanal atresia, clinodactyly of the fifth fingers, urogenital anomalies, congenital muscular torticollis and congenital laryngomalacia. The last two traits have not previously been reported in any trisomy 16q and monosomy 2p cases. The proband was trisomic for the 16q21→qter chromosomal region with the karyotype 46,XY,der(2)t(2;16)(p25;q21)pat. The chromosomal anomaly was the result of unbalanced segregation of a paternal balanced translocation, 46,XY,t(2;16)(p25;q21). In this case, molecular cytogenetic analysis had a critical role in delineating the proband's clinical phenotype. Although this patient had a 16q21→qter duplication and a 2p25.3→pter deletion, the latter may have had mild phenotypic effects when associated with trisomy 16q. The literature was also reviewed, focusing on cases with the same breakpoints, localizations and clinical features reported in recent years.