Hartin Samantha N, Hossain Waheeda A, Francis David, Godler David E, Barkataki Sangjucta, Butler Merlin G
Departments of Psychiatry & Behavioral Sciences and Pediatrics, University of Kansas Medical Center, Kansas City, Kansas.
Cyto-molecular Diagnostic Research Laboratory, Royal Children's Hospital, Victorian Clinical Genetics Services and Murdoch Children's Research Institute, Melbourne, Victoria, Australia.
Mol Genet Genomic Med. 2019 Apr;7(4):e00575. doi: 10.1002/mgg3.575. Epub 2019 Feb 21.
Detailed analysis of imprinting center (IC) defects in individuals with Prader-Willi syndrome (PWS) is not readily available beyond chromosomal microarray (MA) analysis, and such testing is important for a more accurate diagnosis and recurrence risks. This is the first feasibility study of newly developed droplet digital polymerase chain reaction (ddPCR) examining DNA copy number differences in the PWS IC region of those with IC defects.
The study cohort included 17 individuals without 15q11-q13 deletions or maternal disomy but with IC defects as determined by genotype analysis showing biparental inheritance. Seven sets of parents and two healthy, unrelated controls were also analyzed.
Copy number differences were distinguished by comparing the number of positive droplets detected by IC probes to those from a chromosome 15 reference probe, GABRβ3. The ddPCR findings were compared to results from other methods including MA, and whole-exome sequencing (WES) with 100% concordance. The study also estimated the frequency of IC microdeletions and identified gene variants by WES that may impact phenotypes including CPT2 and NTRK1 genes.
Droplet digital polymerase chain reaction is a cost-effective method that can be used to confirm the presence of microdeletions in PWS with impact on genetic counseling and recurrence risks for families.
除染色体微阵列（MA）分析外，目前尚无法对普拉德-威利综合征（PWS）患者的印记中心（IC）缺陷进行详细分析，而此类检测对于更准确的诊断和复发风险评估非常重要。这是一项关于新开发的液滴数字聚合酶链反应（ddPCR）的可行性研究，该技术用于检测存在IC缺陷的PWS患者IC区域的DNA拷贝数差异。
研究队列包括17名无15q11-q13缺失或母源二体，但经基因型分析显示双亲遗传且存在IC缺陷的个体。还分析了7对父母以及2名健康的无关对照。
通过比较IC探针检测到的阳性液滴数量与来自15号染色体参考探针GABRβ3的阳性液滴数量，区分拷贝数差异。将ddPCR结果与包括MA和全外显子组测序（WES）在内的其他方法的结果进行比较，一致性达100%。该研究还估计了IC微缺失的频率，并通过WES鉴定了可能影响表型的基因变异，包括CPT2和NTRK1基因。
液滴数字聚合酶链反应是一种经济有效的方法，可用于确认PWS中微缺失的存在，对家庭的遗传咨询和复发风险评估具有重要意义。
