新生兒篩檢在診斷核黃素反應型多發性醯基輔酶A去氫酶缺乏症（MADD）之可行性研究

Abstract

背景 現行新生兒篩檢可以利用串聯質譜儀分析，對於戊二酸血症第二型（Glutaric aciduia type II; GA II）又稱為多發性醯基輔酶A去氫酶缺乏症(multiple acyl-coenzyme A dehydrogenase deficiency；MADD)的患者提供早期診斷的機會，但目前選用串聯質譜儀分析血片中的數種乙醯肉鹼(acylcarnitines)濃度是否異常的準確度仍有待改進。 方法 我們回顧性的分析了296,929件新生兒篩檢血片串聯質譜議分析的結果，利用檢驗後分析工具Tool runner – GA-II分析，大於35分者依分數高低分為高度懷疑或是可能為GA II (細分為高風險及低風險組)，再採用Taqman single nucleotide polymorphisms (SNP) Genotyping Assays分析這些樣本中是否帶有台灣地區GA II的基因突變熱點（A84T與R99G)，並以定序方式加以確認。 結果 共有1,103件(0.4%)樣本的分數符合為高度懷疑或是可能為GA II。在高度懷疑個案中，三個為其他脂肪酸代謝異常患者，另外有2名個案確認為GA II患者。在高風險及低風險組中的1,091個個案中共發現14個有A84T的突變(13名雜合子及1名同合子)，A84T在此研究中的帶因率為1.35%，與先前文獻的帶因率相似。A84T同合子的乙醯肉鹼數值並無明顯異常的指標。 結論 以Tool runner – GA-II可以有效篩選脂肪酸代謝異常包括GA II的患者，但是無法檢出帶有A84T的新生兒。如何增進此類患者的偵測率仍有待進一步研究。

Background Glutaric acidemia type II (GA II), also known as multiple acyl-coenzyme A dehydrogenase deficiency (MADD), is an autosomal recessive disease caused by electron transfer flavoprotein (ETF) or electron transfer flavoprotein dehydrogenase (ETFDH) defects. Currently, the diagnosis of GA II in newborn screening dependent on tandem mass spectrometry analysis but the sensitivity is unknown. Method We retrospectively analyzed 296,929 acylcarnitines data of newborn screening results using Tool Runner-GA-II. Score higher than 35 were defined as likely or probably (high risk and low risk) to be GA II. We then analyzed if they have A84T and R99G of ETFDH gene by Taqman single nucleotide polymorphisms (SNP) Genotyping Assays. All positive cases were confirmed by direct sequencing. Result Totally 1,103 cases (0.4%) were selected as likely or probably GA II. Six cases were in the likely group included three cases of other fatty acid oxidation defects, and 2 cases of GA II. Fourteen of the 1,091 analyzed cases in the probably groups had A84T mutation (13 heterozygous, 1 homozygous). A84T allele frequency in this study is 1.35%, similar to other studies. The one with A84T homozygous mutation showed normal acylcarnitines at first screening. Conclusion Tool Runner – GA-II can identifies fatty acid oxidation defects including some GA II patients. However, it can’t be a solely tool to detect Taiwan newborns with A84T mutation. Further study is necessary to improve the detection rate.