Department of Pediatrics, National Cheng Kung University Hospital and College of Medicine, Tainan, Taiwan.
Cytogenetic Laboratory, Department of Pathology, National Cheng Kung University Hospital, Tainan, Taiwan.
Taiwan J Obstet Gynecol. 2014 Dec;53(4):598-601. doi: 10.1016/j.tjog.2014.06.003.
Prenatal detection of trisomy 8 mosaicism can be misleading and remains challenging in genetic counseling. Identifying cases of partial or complete trisomy 8 mosaicism will highlight the pitfalls of conventional karyotyping in prenatal amniocentesis for partial or complete trisomy 8 mosaicism.
The patient was born uneventfully at term to a healthy 34-year-old mother. Analysis of the amniotic fluid (AF) cells showed a normal male karyotype. At birth, the newborn presented dysmorphic features, including asymmetric mandibles and ears, anteverted nostrils with a relatively long philtrum, retrognathia, and a clenched hand on the left side. Imaging studies revealed agenesis of the corpus callosum with bilateral colpocephaly, a common arterial trunk bifurcating into the left subclavian and carotid arteries, and bilateral pelviectasis. Cytogenetic analysis of the blood revealed mosaicism of partial trisomy 8: 47,XY,+del(8) (q21.3) [8]/46,XY [12]. Array comparative genomic hybridization (array-CGH) revealed 82.9 Mb duplications at chromosome 8p23.3-8q21.3 with dosage variations. Interphase fluorescence in situ hybridization analysis of urine sediments and buccal smears were compatible with mosaic compositions. A small colony of AF cells was found to have partial trisomy 8 in repeated analysis.
Conventional karyotyping through amniocentesis has limitations particularly in detecting rare trisomy mosaicism if trisomic cells show growth disadvantage. Array-CGH using uncultured cells may be of help in providing more information on genetic dosage variations in such cases.
产前检测 8 三体嵌合体可能存在误导，在遗传咨询中仍然具有挑战性。识别部分或完全 8 三体嵌合体病例将突出显示传统核型分析在产前羊膜穿刺术部分或完全 8 三体嵌合体中的局限性。
患者足月顺产，母亲健康，34 岁。羊水（AF）细胞分析显示正常男性核型。新生儿出生时表现出畸形特征，包括不对称的下颌骨和耳朵、前鼻孔相对较长、下颌后缩和左侧紧握的手。影像学研究显示胼胝体发育不全，双侧脑膨出，共同动脉干分叉为左锁骨下动脉和颈动脉，双侧肾盂扩张。血液细胞遗传学分析显示部分 8 三体嵌合体：47，XY，+del（8）（q21.3）[8]/46，XY[12]。阵列比较基因组杂交（array-CGH）显示 8p23.3-8q21.3 染色体 82.9 Mb 重复，剂量变化。尿液沉淀物和口腔涂片的间期荧光原位杂交分析与嵌合体成分一致。重复分析发现一小部分羊水细胞存在部分 8 三体。
如果三体细胞表现出生长劣势，通过羊膜穿刺术进行的传统核型分析在检测罕见的三体嵌合体方面存在局限性。使用未培养细胞的 array-CGH 可能有助于提供此类情况下遗传剂量变化的更多信息。
