Baqri Wafa, Goh Elaine S, Berndl Anne, Seesahai Judy, Skidmore Martin, Vaags Andrea K, Kekis Mariana
Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
Laboratory Medicine and Genetics, Trillium Health Partners, Mississauga, Ontario, Canada.
Mol Genet Genomic Med. 2025 Sep;13(9):e70138. doi: 10.1002/mgg3.70138.
Human chimerism is rare, and most prevalent with discordant chromosomal sex. We report a male 46,XY/46,XY chimera, born through a spontaneously conceived pregnancy to a healthy 32-year-old G1P0 Indian, African, and Scottish female and her 34-year-old healthy Chinese partner. The prenatal presentation and postnatal outcomes are described.
A prenatal cell-free DNA screening test, amniocentesis with QF-PCR and SNP microarray, and postnatal microarray and FISH study on peripheral blood, placenta, and umbilical cord were used to evaluate chimerism.
The prenatal cell-free screening test revealed high risk for triploidy/vanishing twin, but there was no confirmation from early ultrasound. Subsequent QF-PCR on amniocytes showed a profile suggestive of a tetragametic chimera. G-banding showed a 46,XY karyotype. A SNP microarray detected two copy number gains of uncertain significance on chromosome 6q, derived from the father who was a balanced carrier of ins(6;11). A postnatal microarray and FISH study confirmed the presence of two cell lines, each with a 46,XY complement but with different submicroscopic structural changes including recombinant and insertion changes. Clinical evaluations of the child at birth and 8 weeks of age were coordinated to detect the presence of chimeric symptoms.
With a confirmed incidental finding of 46,XY/46,XY chimerism, we present that underlying same-sex chimerism may be under-recognized.
人类嵌合体很罕见，在染色体性别不一致的情况中最为常见。我们报告了一名46,XY/46,XY嵌合体男性，其母亲是一名健康的32岁印度、非洲和苏格兰混血G1P0女性，父亲是一名34岁健康的中国男性，此次妊娠为自然受孕。本文描述了该病例的产前表现和产后结局。
采用产前游离DNA筛查试验、QF-PCR和单核苷酸多态性（SNP）微阵列羊水穿刺术，以及产后对外周血、胎盘和脐带进行微阵列和荧光原位杂交（FISH）研究来评估嵌合现象。
产前游离DNA筛查试验显示三倍体/消失双胎的高风险，但早期超声未得到证实。随后对羊水细胞进行的QF-PCR显示出提示四配子嵌合体的图谱。G显带显示为46,XY核型。SNP微阵列检测到6号染色体长臂存在两个意义不明的拷贝数增加，来源于父亲，父亲是ins(6;11)的平衡携带者。产后微阵列和FISH研究证实存在两种细胞系，每个细胞系均具有46,XY核型，但存在不同的亚微观结构变化，包括重组和插入变化。对该患儿出生时和8周龄时进行了临床评估，以检测嵌合症状的存在。
经证实偶然发现46,XY/46,XY嵌合现象，我们认为潜在的同性嵌合现象可能未得到充分认识。
