Prader-Willi Syndrome （PWS） is a genetic disorder that is difficult to detect, particularly at an early age. PWS is caused by disruption of normal, epigenetically controlled gene function in the chromosome 15q11-q13 region. Clinical symptoms are difficult to diagnose in infants and only become clearer at later ages as the patients develop hyperphagia and morbid obesity. Molecular genetic tests are able to definitively diagnose PWS and allow early diagnosis of the syndrome. High resolution cytogenetic testing, methylation-specific PCR （MS-PCR）, and linkage analysis are routinely used to diagnose PWS. To establish a linkage analysis method for Chinese patients, this study identified a useful set of STR markers in the typical PWS deletion and adjacent area, for linkage analysis in two Chinese families with PWS offspring. Using this method, the authors confn＇rned that one patient had a paternal deletion in chromosome 15q 11-q 13 and the other patient had maternal uniparental heterodisomy of chromosome 15. MS -PCR and high resolution chromosome G-banding also confirmed this diagnosis. This linkage analysis method can detect both deletion and uniparental disomy, thus providing valuable information for genetic counseling and the opportunity to analyze the relationship between the genotype and phenotype of PWS.
目的探索一种快速确定缺失或插入突变杂合子DNA序列的简便方法。方法采用PCR-聚丙烯酰胺凝胶电泳（polyacrylamide gel electrphoresis，PAGE）一切胶回收-二次PCR-测序的方法，分析P基因1920del30 bp和insAACA杂合突变的突变等位基因序列。结果获得了准确的突变等位基因序列。结论PCR—PAGE电泳-切胶回收-二次PCR-测序方法可准确鉴定缺失／插入突变杂合子个体突变等位基因DNA序列，在多方面优于克隆测序。
目的对1例眼皮肤白化病(OCA)患儿进行基于 DNA 的分型诊断,并在此基础上进行 OCA 产前基因诊断。方法应用 PCR 技术、DNA 序列测定技术和变性高效液相层析(DHPLC)技术,分析患儿及其父母的 OCA 相关基因,确定患儿的分型诊断和基因型后,于其母孕20周时取羊水,以 DNA 序列测定技术进行 OCA 产前基因诊断。结果先证者 TYR 基因未见突变,1对 P 基因分别存在 N476D 和 Y827H 突变。群体中100名表型正常者中未见此2种突变等位基因。胎儿获得了母源性 N476D 突变,未获得父源性 Y827H 突变,推测胎儿为表型正常的致病基因携带者。胎儿出生后表型正常,与产前基因诊断结果相符。结论成功开展了1例 OCA2产前基因诊断并发现2种致病性 P 基因新突变 N476D 和 Y827H,对今后开展该病的基础研究和预防与优生工作具有重要意义。
