Gasparini Yanca, Montenegro Marília M, Novo-Filho Gil M, Ceroni José R M, Honjo Rachel S, Zanardo Évelin A, Dias Alexandre T, Nascimento Amon M, Costa Taís V M M, Madia Fabrícia A, Chehimi Samar N, Damasceno Jullian G, Kim Chong A, Kulikowski Leslie D
Cytogenet Genome Res. 2019;157(3):153-157. doi: 10.1159/000498836. Epub 2019 Apr 2.
Mosaic trisomy 12 is a rare anomaly, and only 9 cases of live births with this condition have been reported in the literature. The clinical phenotype is variable, including neuropsychomotor developmental delay, congenital heart disease, microcephaly, cutaneous spots, facial asymmetry, prominent ears, hypotonia, retinopathy, and sensorineural hearing loss. A 2-year-old female presented with neuropsychomotor developmental delay, prominent forehead, dolichocephaly, patchy skin pigmentation, and unexpected overgrowth at birth. Cytogenetic analysis of her peripheral blood showed normal results, suggesting the presence of a chromosomal alteration in other tissues. Further studies using G-banding and FISH performed on fibroblasts from both hyper- and hypopigmented regions identified a 47,XX,+12/46,XX karyotype. To the best of our knowledge, no patients with mosaic trisomy 12 associated with overgrowth have been reported to date. Congenital overgrowth and neonatal overgrowth have been frequently linked to Pallister-Killian syndrome (PKS; OMIM 601803). This case suggests the possibility of an association of genes present in the 12p region with fetal overgrowth, considering that chromosomal duplications could lead to an increase in the production of aberrant transcripts and disturbing gene dosage effects. This case highlights the importance of cytogenetic analysis in different tissues to provide relevant information to the specific genotype/phenotype correlation.
12号染色体嵌合三体是一种罕见的异常情况，文献中仅报道过9例患有这种疾病的活产病例。其临床表型多样，包括神经精神运动发育迟缓、先天性心脏病、小头畸形、皮肤斑点、面部不对称、耳朵突出、肌张力减退、视网膜病变和感音神经性听力损失。一名2岁女性表现出神经精神运动发育迟缓、前额突出、长头畸形、皮肤色素沉着斑以及出生时意外的过度生长。对其外周血进行的细胞遗传学分析结果正常，提示其他组织中存在染色体改变。对色素沉着过多和过少区域的成纤维细胞进行的G显带和荧光原位杂交进一步研究确定了47,XX,+12/46,XX核型。据我们所知，迄今为止尚未报道过与过度生长相关的12号染色体嵌合三体患者。先天性过度生长和新生儿过度生长常与帕利斯特-基利安综合征（PKS；OMIM 601803）有关。该病例提示12p区域存在的基因与胎儿过度生长相关的可能性，考虑到染色体重复可能导致异常转录本产生增加并干扰基因剂量效应。该病例突出了对不同组织进行细胞遗传学分析以提供特定基因型/表型相关性相关信息的重要性。
