Newborn screening for PKU and BH4 responsiveness

1958年，罗伯特·华纳博士找到罗伯特·古特里博士，寻求帮助，以开发一种更好的方法， 测量新生儿血液中的苯丙氨酸这种相互作用产生了细菌抑制试验 以及开始以人群为基础的新生儿苯丙酮尿症（PKU）筛查。及早识别 受影响的新生儿使用苯丙氨酸限制饮食避免了不可逆的脑损伤。虽然BIA 已经被串联质谱法取代作为测量苯丙氨酸的手段，PKU仍然是 通过前瞻性识别无症状患者有效治疗疾病的范例。PKU 苯丙氨酸羟化酶（PAH）缺陷导致不能将苯丙氨酸转化为 酪氨酸。通过饮食方式治疗苯丙酮尿症在很大程度上保持不变，直到几个小组确定了一个亚组， 使用PAH酶的强制性辅因子6R-四氢生物蝶呤（BH 4）可治疗的患者集， 没有苯丙氨酸限制饮食。虽然BH4反应患者倾向于轻度PKU， 高苯丙氨酸血症;典型的PKU患者已被表征为BH 4反应性。分析 PAH基因正成为决定BH4反应的一个重要方面。全面分析 PAH基因可采用普遍采集的新生儿筛查干血卡为来源 的DNA。使用干血卡和新兴的高分辨率熔体分析技术， PAH的综合分析可以在异常新生儿筛查的1.5天内轻松完成 结果当生理Phe/BH4负荷试验结果完成时，基因型数据将在手。 将生理分析和遗传分析相结合，可以有效地鉴定BH4反应型 PKU患者。导致BH4反应性疾病的PAH突变的编目正在进行中，因此开发了一种 分析PAH基因的灵敏、快速和经济有效的方法将对临床医生和 研究人员在此提出使用高分辨率熔体分布来开发简化的且 评估编码序列和内含子区域的简化方法，这些区域对mRNA加工至关重要， PAH基因。高分辨率熔解曲线分析是快速的，灵敏度至少等于DNA序列分析 并且超过了其它的预序列扫描技术。高分辨率熔体轮廓将在以下方面发挥作用： 鉴定BH4应答性PKU患者。

In 1958, Dr Robert Guthrie was approached by Dr Robert Warner seeking aid to develop a better means to measure phenylalanine in the blood of newborns. Of this interaction was born the bacterial inhibition assay and the beginning of population-based newborn screening for phenylketonuria (PKU). Early identification of affected newborns avoided irreversible brain damage using a phenylalanine-restricted diet. While the BIA has been replaced by tandem mass spectrometry as the means to measure phenylalanine, PKU remains the paradigm for a disorder effectively treated by prospective identification of asymptomatic patients. PKU results from defects in phenylalanine hydroxylase (PAH) causing an inability to convert phenylalanine to tyrosine. Treating PKU by dietary means remained largely unchanged until several groups identified a sub- set of patients treatable using 6R-tetrahydrobiopterin (BH4), the obligatory co-factor of the PAH enzyme, without the phenylalanine restricted diet. While BH4-responsive patients are skewed to mild PKU and hyperphenyla'ianemia; classic PKU patients have been characterized as BH4 responsive. Analysis of the PAH gene is becoming an important aspect to determining BH4 response. Comprehensive analysis of the PAH gene may be performed using the universally collected newborn screening dried blood card as a source of DNA. Using the dried blood card and the emerging technology of high-resolution melt profiling, comprehensive analysis of PAH may be easily completed within 1.5 days of abnormal newborn screening results. Genotypic data will be in hand when results of the physiological Phe/ BH4 loading test are complete. Combining physiological analysis and genetic analysis will lead to effective identification of BH4 responsive PKU patients. Cataloging PAH mutations resulting in BH4 responsive disease is underway thus developing a sensitive, rapidly, and cost effective means to analyze the PAH gene will have utility to clinicians and researchers. Herein is proposed the use of high resolution melt profiling to develop a simplified and streamlined means of assessing the coding sequence and intronic regions critical to mRNA processing in the PAH gene. High resolution melt profiling is rapid with sensitivity at least equal to DNA sequence analysis and in excess of other pre-sequence scanning technologies. High resolution melt profiling will play a role to identify BH4 responsive PKU patients.