Mishra R, Paththinige C S, Sirisena N D, Nanayakkara S, Kariyawasam U G I U, Dissanayake V H W
Human Genetics Unit, Faculty of Medicine, University of Colombo, Kynsey Road, Colombo, 00800, Sri Lanka.
Civil Service Hospital, Minbhawan Marg, Minbhawan, Kathmandu, 44600, Nepal.
BMC Pediatr. 2018 Jan 8;18(1):4. doi: 10.1186/s12887-017-0980-z.
Partial trisomy is often the result of an unbalanced segregation of a parental balanced translocation. Partial trisomy16q is characterized by a common, yet non-specific group of craniofacial dysmorphic features, and systemic malformations with limited post-natal survival. Most of the cases of partial trisomy 16q described in the scientific literature have reported only one, or less frequently two cardiac defects in the affected babies. Herein, we report a case of partial trisomy 16q21➔qter with multiple and complex cardiac defects that have not previously been reported in association with this condition.
We report the phenotypic and cytogenetic features of a Sri Lankan female infant with partial trisomy 16q21➔qter. The baby had a triangular face with downslanting eyes, low set ears and a cleft palate. Systemic abnormalities included multiple cardiac defects, namely double outlet right ventricle, ostium secundum atrial septal defect, mild pulmonary stenosis, small patent ductus arteriosus, and bilateral superior vena cavae. An anteriorly placed anus was also observed. The proband was trisomic for 16q21➔qter chromosomal region with a karyotype, 46,XX,der(15)t(15;16)(p13;q21)mat. The chromosomal anomaly was the result of an unbalanced segregation of a maternal balanced translocation; 46,XX,t(15;16)(p13;q21). Partial trisomy 16q was established by fluorescence in-situ hybridization analysis.
The craniofacial dysmorphic features and the presence of cardiac and anorectal malformation in the proband are consistent with the phenotypic spectrum of partial trisomy 16q reported in the scientific literature. More proximal breakpoints in chromosome 16q are known to be associated with multiple cardiac abnormalities and poor long-term survival of affected cases. This report presents a unique case with multiple, complex cardiac defects that have not previously been described in association with a distal breakpoint in 16q. These findings have important diagnostic and prognostic implications.
部分三体性通常是亲代平衡易位不平衡分离的结果。16q部分三体性的特征是一组常见但非特异性的颅面畸形特征以及全身性畸形，出生后存活率有限。科学文献中描述的大多数16q部分三体性病例报告，受影响婴儿仅出现一种心脏缺陷，或较少见的两种心脏缺陷。在此，我们报告一例16q21➔qter部分三体性病例，其具有多种复杂心脏缺陷，此前尚未见与该病症相关的报道。
我们报告了一名患有16q21➔qter部分三体性的斯里兰卡女婴的表型和细胞遗传学特征。该婴儿面部呈三角形，眼睛向下倾斜，耳朵低位，并有腭裂。全身性异常包括多种心脏缺陷，即右心室双出口、继发孔型房间隔缺损、轻度肺动脉狭窄、小型动脉导管未闭和双侧上腔静脉。还观察到肛门位置靠前。先证者的16q21➔qter染色体区域三体性，核型为46,XX,der(15)t(15;16)(p13;q21)mat。染色体异常是母亲平衡易位不平衡分离的结果；46,XX,t(15;16)(p13;q21)。通过荧光原位杂交分析确定为16q部分三体性。
先证者的颅面畸形特征以及心脏和肛门直肠畸形的存在与科学文献中报道的16q部分三体性的表型谱一致。已知16q染色体上更靠近近端的断点与多种心脏异常以及受影响病例的长期存活率低有关。本报告呈现了一例具有多种复杂心脏缺陷的独特病例，此前未见与16q远端断点相关的描述。这些发现具有重要的诊断和预后意义。
