Christofolini Denise M, Piazzon Flavia B, Evo Carolina, Mafra Fernanda A, Cosenza Stella R, Dias Alexandre T, Barbosa Caio P, Bianco Bianca, Kulikowski Leslie D
Department of Gynecology and Obstetrics, Genetics Division, Faculdade de Medicina do ABC - FMABC, São Paulo, Brazil.
Department of Pathology, Cytogenomics Laboratory, LIM 03, HC-FMUSP, University of São Paulo, Av. Dr. Enéas de Carvalho Aguiar 255, São Paulo 05403-000, Brazil.
Mol Cytogenet. 2014 Apr 24;7:29. doi: 10.1186/1755-8166-7-29. eCollection 2014.
Complex small supernumerary marker chromosomes (sSMCs) consist of chromosomal material derived from more than one chromosome and have been implicated in reproductive problems such as recurrent pregnancy loss. They may also be associated with congenital abnormalities in the offspring of carriers. Due to its genomic architecture, chromosome 15 is frequently associated with rearrangements and the formation of sSMCs. Recently, several different CNVs have been described at 16p11.2, suggesting that this region is prone to rearrangements.
We detected the concomitant occurrence of partial trisomy 15q and 16p, due to a complex sSMC, in a 6-year-old girl with clinical phenotypic. The karyotype was analyzed by G and C banding, NOR staining, FISH and SNP array and defined as 47,XX,+der(15)t(15;16)(q13;p13.2)mat. The array assay revealed an unexpected complex sSMC containing material from chromosomes 15 and 16, due to an inherited maternal translocation (passed along over several generations). The patient's phenotype included microsomia, intellectual disability, speech delay, hearing impairment, dysphagia and other minor alterations.
This is the first report on the concomitant occurrence of partial trisomy 15q and 16p. The wide range of phenotypes associated with complex sSMCs represents a challenge for genotype-phenotype correlation studies, accurate clinical assessment of patients and genetic counseling.
复杂的小额外标记染色体（sSMC）由来自不止一条染色体的染色体物质组成，并与反复流产等生殖问题有关。它们也可能与携带者后代的先天性异常有关。由于其基因组结构，15号染色体经常与重排和sSMC的形成有关。最近，在16p11.2处描述了几种不同的拷贝数变异（CNV），表明该区域易于发生重排。
我们在一名具有临床表型的6岁女孩中检测到由于复杂的sSMC导致的15q和16p部分三体同时出现。通过G带和C带、核仁组织区（NOR）染色、荧光原位杂交（FISH）和单核苷酸多态性（SNP）阵列分析了核型，定义为47,XX,+der(15)t(15;16)(q13;p13.2)mat。阵列分析显示由于遗传的母源易位（经过几代传递），存在一个意外的包含15号和16号染色体物质的复杂sSMC。患者的表型包括身材矮小、智力残疾、语言发育迟缓、听力障碍、吞咽困难和其他轻微改变。
这是关于15q和16p部分三体同时出现的首次报告。与复杂sSMC相关的广泛表型对基因型-表型相关性研究、患者的准确临床评估和遗传咨询构成了挑战。
