单亲分体(UPD)是指染色体的两个同源物仅从一个亲本遗传而没有来自另一个亲本的代表性拷贝。UPD在人口中的患病率估计为0.15‰。目前对UPD的理解仅限于由于印迹障碍或隐性疾病而导致UPD与临床表现相关的受试者。节段性UPD很少见,特别是对于具有异体和等体组合的节段性UPD。本文介绍了一对具有相互易位46,XY,PGT-SR的t(14;22)(q32.3;q12.2)。在8个活检囊胚中,通过B等位基因频率检测到一个具有节段性杂合性缺失(LOH)(22)[arr[hg19]q12.1q22.3(28,160,407-35,407,407,682)]的整倍体囊胚(第4号)。我们发现染色体同时包含UPiD(22)[arr[hg19]q12.1q22.3(28,160,407-35,407,407,682)×2hmzmat]和UPhD(22)[arr[hg19]q22.3qter(35407,682-51,169,045)×2htzmat]。UPDtool软件确认了结果。更重要的是,分段UPD和相互易位共享相同的断点,chr22q12.1(28,160,407),而等分和异分之间的断点为chr22q22.3(35,407,682)。我们报道了第一个节段性UPD,包括异体和等体,这可能是由于非整倍性抢救。该病例强调综合染色体筛查和单倍型分析相结合对降低误诊风险的重要性。
Uniparental disomies (UPD) refers to the inheritance of both homologs of a chromosome from only one parent with no representative copy from the other parent. UPD was with an estimated prevalence of 0.15‰ in population. Current understanding of UPD was limited to subjects for which UPD was associated with clinical manifestation due to imprinting disorders or recessive diseases. Segmental UPD was rare, especially for a segmental UPD with a combination of hetero- and isodisomy. This paper presents a couple with reciprocal translocation 46,XY, t(14;22)(q32.3;q12.2) for PGT-SR. Among 8 biopsied blastocysts, one euploid blastocyst (No.4) with segmental loss of heterozygosity (LOH)(22) [arr[hg19] q12.1q22.3 (28,160,407 - 35,407,682)] was detected by B allele frequency. We found the chromosome contained both UPiD(22) [arr[hg19] q12.1q22.3 (28,160,407 - 35,407,682) ×2 hmz mat] and UPhD(22) [arr[hg19] q22.3qter(35,407,682 - 51,169,045) ×2 htz mat] by haplotype analysis. UPDtool software confirmed the result. What\'s more, the segmental UPD and reciprocal translocation shared the same breakpoint, chr22q12.1 (28,160,407), while the breakpoint between iso- and heterodisomy was chr22q22.3 (35,407,682). We reported the first segmental UPD with a combination of hetero- and isodisomy, which may result from aneuploidy rescue. This
case emphasizes the importance of the combination of comprehensive chromosome screening and haplotype analysis to reduce the risk of misdiagnosis.