| Abstract: | 近年來次端粒的重組已經被認為是造成智力障礙或畸型特徵的主要原因。在這些不明原因的智力障礙中大約5-10％是跟次端粒的重組有關。次端粒的重組，例如，染色體的缺失和重複，因為片段太小而無法利用傳統的細胞遺傳方法來診斷，因此，我們選擇一個簡單、快速，經濟且有效的分析方法—MLPA (多重連接探針擴增法)來偵測次端粒的異常。MLPA是利用41種次端粒的探針先和染色體的DNA雜交後,將雜交的5'端探針和3'端探針接合再利用PCR放大接合的探針。MLPA能夠在單一反應中篩檢所有染色體末端且不需要父母的DNA。
本實驗篩檢49位不明原因智力障礙，特徵奇怪，先天性異常或有家族史智障的南投教養院學童。利用兩種的次端粒探針套組SALSA P019, P020來偵測。結果，若以波峰面積作為統計數值，則發現22位學童次端粒異常，其中9位有次端粒缺失的情形；20位有次端粒重複的情形。然而，若以波峰的高度當做統計數據，則有16位學童次端粒異常，其中12位有次端粒缺失的情形；6位有次端粒重複的情形。另外，發現一例家族性遺傳：46,XY, der(19)t(16;19)，其異常是來自於母親。
在本實驗，MLPA的價值是被認定的，它可以同時進行處理大量的檢體以減少實驗室工作。因此，它是一個快速且值得信賴作為篩檢次端粒的方法，未來可以開發在例行性診斷之使用。
In recent years, subtelomeric rearrangements have been identified as a major cause of mental retardation and/or malformation syndromes. These
aberrations account for roughly 5 to 10% of all mental retardation. Subtelomeric rearrangemens were too small to be detected by conventional cytogenetic analysis, so we use an easy, rapid, economical and efficient tool--MLPA to diagnose subtelomeric aberration. Multiplex ligation dependent probe amplification（MLPA） are based on PCR amplification of ligated probes hybridized to chromosome ends. 41 telomeres can be screened all chromosome ends in a single reaction without the need for parental DNAs.
We have tested 49 individuals with idiopathic MR, dysmorphic features, congenital malformations, and/ or family history of MR. Two sets of subtelomeric probes, the SALSA P019 and P020 human telomere test kit, were used. A subtelomeric aberration account for peak area was identified in 22 patients (44.8%) (nine deletions and twenty duplications).For peak height, there were 16 subtelomeric aberrations（32.7％）（twelve deletions and six duplications）. In addition, there was one aberration that identified by MLPA were inherited form his mother：46,XY, der(19)t(16;19)mat.
In this study, the value of MLPA is confirmed. It allows large number of samples to be processed simultaneously and thus significantly reducing laboratory work. This study demonstrates that MLPA is a fast and reliable method for subtelomeric screening, potentially suitable for use in routine diagnostics. |
