高苯丙氨酸血症患儿苯丙氨酸负荷试验后苯丙氨酸和酪氨酸浓度变化

目的了解苯丙氨酸负荷试验对高苯丙氨酸血症HPA患儿血苯丙氨酸Phe和酪氨酸Tyr浓度及其比值Phe/Tyr的影响。方法HPA组30例,非HPA儿童(对照组)33例。所有儿童均空腹口服Phe100mg/kg,分别于服Phe前0h、服Phe后1h、2h、3h、4h采手指血,滴于滤纸片上,取直径3mm干血滤纸片,经含Phe和Tyr同位素内标的甲醇萃取,盐酸正丁醇衍生,进行串联质谱分析,测定Phe、Tyr浓度和Phe/Tyr值。结果血Phe浓度HPA组于服Phe后2h最高,服Phe后4h仍维持在较高水平,对照组于服Phe后1h值最高,服Phe后4h下降至接近正常浓度,两组比较各时间段差异均有显著性(P<0.001)。Tyr浓度HPA组各时间段差异无显著性,对照组于服Phe后逐渐升高,各时间段差异有显著性P<0.05,于服Phe后2h、3h时高于HPA组,差异有显著性(P<0.05)。Phe/Tyr值HPA组各时间段均高于对照组,差异非常显著(P<0.001)。结论HPA患儿Phe代谢速度下降,测定血Phe浓度结合Phe/Tyr值有助于HPA诊断。     

高苯丙氨酸血症患儿尿中代谢物水平分析

目的通过检测高苯丙氨酸血症(HPA)患儿血苯丙氨酸(Phe)及尿苯丙酮酸、苯乙酸及苯乳酸水平,探讨其血Phe水平与尿代谢产物的关系。方法研究对象为55例HPA患儿,其中20例为轻度HPA(血Phe浓度<360 mmol/L)、35例为苯丙酮尿症(PKU,血Phe浓度360~1 200 mmol/L);血Phe水平检测采用串联质谱干血滤纸片法;尿苯丙酮酸、苯乙酸及苯乳酸水平检测采用尿素酶预处理气相色谱-质谱法。结果 HPA患儿血Phe水平与尿苯丙酮酸、苯乙酸及苯乳酸水平呈正相关(r=0.61~0.84,P均<0.01)。轻度HPA与PKU患儿尿苯丙酮酸、苯乙酸及苯乳酸水平差异有统计学意义(P均<0.01);70%轻度HPA患儿及5.71%PKU患儿的尿苯丙酮酸、苯乙酸及苯乳酸水平正常。结论 HPA患儿尿中苯丙酮酸、苯乙酸及苯乳酸水平的变化与血Phe浓度密切相关,单纯检测尿苯丙酮酸、苯乙酸及苯乳酸可能导致假阴性。     

不同类型高苯丙氨酸血症的临床表型

目的探讨不同类型高苯丙氨酸血症（HPA）临床表型,了解HPA患者对低苯丙氨酸（Phe）饮食治疗的反应性。方法HPA患儿44例均口服四氢生物喋呤（BH4）负荷试验（20 mg/kg）或Phe-BH4联合负荷试验,同时进行尿喋呤谱分析、红细胞二氢喋呤还原酶（DHPR）测定。治疗前采用Gesell发育量表进行智力测定并行脑电图检查。予苯丙氨酸羟化酶（PAH）缺乏症患者低Phe饮食治疗,控制血Phe在120~360μmol/L,监测Phe耐受量。结果1.确诊BH4反应性PAH缺乏症患儿12例。男7例,女5例;平均年龄7.8个月;生化代谢表型均为轻度或中度HPA。2.部分BH4缺乏症患儿确诊前经低Phe饮食治疗后血Phe可以控制在较低水平,但仍出现进行性神经损害,脑电图异常率为72.7%。3.BH4反应性PAH缺乏症的发育商明显高于其他HPA;饮食治疗中的Phe耐受量较高。结论BH4反应性PAH缺乏症患者对饮食治疗的反应性更好。早期BH4缺乏症的鉴别诊断非常重要。     

四氢生物蝶呤负荷试验诊断四氢生物蝶呤反应性苯丙氨酸羟化酶缺乏症的临床研究

目的探讨四氢生物蝶呤(BH4)反应性苯丙氨酸羟化酶(PAH)缺乏症的临床诊断方法,进一步了解其临床特征,为该型患儿应用BH4药物治疗提供科学依据。方法73例高苯丙氨酸血症(HPA)患儿,男47例,女26例,平均年龄1.93个月。所有患儿都进行口服BH4负荷试验,同时进行尿蝶呤谱分析、红细胞二氢蝶啶还原酶测定。对其中血苯丙氨酸(Phe)浓度<600μmol/L者给予口服Phe BH4联合负荷试验,对部分BH4反应性PAH缺乏症患儿,在普食条件下给予BH4片剂(10～20mg/kg)替代治疗6～7天,观察其疗效。结果(1)在BH4负荷试验中,不同类型HPA患儿的血Phe浓度表现出特征性的曲线改变,22例诊断为经典型苯丙酮尿症(PKU),39例中度PKU,12例四氢生物蝶呤缺乏症;(2)在中度PKU患儿中发现22例(56.4%)对BH4有反应;(3)6例BH4反应性PAH缺乏症患儿以BH410mg/kg治疗6～7天,其中4例血Phe浓度能控制到正常或接近正常治疗水平,另2例BH4需增加到20mg/kg使Phe浓度显著下降。结论在BH4负荷试验中,部分因苯丙氨酸羟化酶缺乏引起的中轻度PKU患儿对BH4有反应性,给予这些患儿BH4治疗可部分或全部替代低苯丙氨酸饮食治疗,拓宽了PKU的治疗方法,有助于提高患儿的生活质量。     

高苯丙氨酸血症56例临床研究

目的探讨高苯丙氨酸血症的早期诊断以及治疗时间与疗效之关系。方法采用时间分辨化学荧光法,测定56例患儿血苯丙氨酸(Phe)浓度,血Phe浓度持续>120μmol/L(2mg/dl)诊断为高苯丙氨酸血症。同时作四氢生物喋呤(BH4)负荷试验、尿喋呤谱分析、红细胞二氢喋定还原酶(DHPR)活性测定进行进一步确诊和苯丙酮尿症(PKU)、BH4缺乏症的鉴别诊断。一经确诊立即行低苯丙氨酸饮食治疗。结果出生筛查阳性患儿立即治疗及初治年龄≤6个月者,智力发育与正常同龄儿差异无统计学意义;初治年龄>6个月者智力发育与正常同龄儿差异有统计学意义。结论新生儿疾病筛查意义重大,早期、合理治疗预后良好。     

苯丙氨酸负荷实验筛选苯丙酮尿症杂合子

目的初步建立口服苯丙氨酸负荷实验筛选苯丙酮尿症(PKU)杂合子的方法。方法采用病例对照研究,观察4例PKU杂合子(为已确诊PKU患儿的父母)和4例年龄、性别、体质量与前者相匹配的健康对照者,空腹、口服苯丙氨酸后1、2、3、4、6、24 h,血清苯丙氨酸(Phe)、酪氨酸(Tyr)浓度及其比值(Phe/Tyr)的变化。血清Phe、Tyr浓度采用高效液相色谱仪测定。结果口服Phe 2 h,PKU杂合子与对照者的Phe/Tyr均达到峰值,两者间血清Phe浓度和Phe/Tyr呈现显著差异(P<0.05);且两者之间的数值范围无重叠,其中Phe/Tyr的差距更大。结论口服苯丙氨酸负荷实验有助于筛选人群中的PKU杂合子。     

苯丙氨酸羟化酶缺乏症患儿基因型和表型关系及其临床应用的研究

目的构建苯丙氨酸羟化酶(PAH)缺乏症患儿的PAH基因变异谱,研究基因型和表型的关系。方法回顾分析76例经新生儿筛查确诊的PAH缺乏症患儿的PAH基因变异位点,建立基因型-表型预测模型。对等位基因进行赋值,设定变异位点特定值(AV),并计算AV评分之和,进而预测临床表型。结果应用第二代高通量测序技术和多重连接酶探针依赖扩增检测(MLPA)技术,在76例新生儿152个PAH等位基因中共检测出146个变异位点,频率为96.1%。70例新生儿检测出2个变异等位基因,其中3例纯合变异,67例复合杂合变异;另外6例检测出1个变异等位基因。共检测出变异类型45种,变异频率较高的位点为c.728GA(26/146,17.8%)、c.158GA(13/146,8.9%)、c.1068CA(11/146,7.5%)、c.721CT(10/146,6.8%),c.1238GC(8/146,5.5%)、c.331CT(8/146,5.5%)、c.1301CA(7/146,4.8%)。其中c.95AG位点未曾被BIOPKU数据库报道。患儿治疗前血苯丙氨酸(Phe)浓度与AV评分之和呈显著负相关(r=-0.83,P0.001)。随访发现2例轻度高苯丙氨酸血症患儿血Phe浓度120 μmol/L者无需治疗。结论构建常见PAH基因变异谱,验证了PAH基因突变和表型的相关性,有助于PAH确诊及分型、早期判断预后以及遗传咨询。     

血脑苯丙氨酸转运与苯酮尿症临床表型的关系及治疗新探索

苯酮尿症患者血中高浓度的苯丙氨酸（Phe）与其他大分子中性氨基酸竞争血脑屏障氨基酸转运体进入脑内,影响脑发育。通过氢磁共振波谱分析可测定脑Phe浓度,通常血,脑Phe的浓度比例约为3：1。研究发现,脑Phe浓度较血Phe浓度与临床表型的相关性更大。个体血脑屏障对Phe的转运与脑Phe浓度相关,高表观转运米氏常数、低最大转运速率,脑内消耗率者的脑Phe浓度较低,对脑白质的损伤及智能发育的影响均较小;采用大分子中性氨基酸制剂可降低患者脑内Phe浓度,改善脑内神经递质合成,成为苯酮尿症治疗方面的又一新的探索。     

新生儿高苯丙氨酸血症筛查及PAH基因变异和缺失分析

目的 了解石家庄市新生儿高苯丙氨酸血症（HPA）的发病率、临床分型以及相关基因的变异特征。方法选择2017年3月至2021年5月在石家庄市新生儿疾病筛查中心进行HPA筛查的487 380名新生儿，经免疫荧光法检测其足跟血苯丙氨酸浓度，采用基因测序技术对可疑阳性患儿苯丙氨酸羟化酶（PAH）基因进行检测，患儿父母采用Sanger法进行目标基因变异验证，进一步将基因测序结果与正常人比对，找出片段缺失区域并进行分析。结果487 380名新生儿中筛查出阳性儿191例，确诊HPA 104例，均为PAH缺乏症，发病率为1/4686。104例患儿中共检测出62种基因变异，包括错义变异37种、剪接变异10种、无义变异7种、同义变异2种、整码变异1种以及杂合缺失5种。PAH基因常见的变异位点有c. 158 G>A(18.7%)、c. 728 G>A(10.5%)、c. 611 A>G(6.7%)、c. 331 C>T(4.8%)和c.721C>T(4.8%)，并发现未报道基因片段缺失（外显子6杂合缺失）及基因变异（c.630T>G、c.61-1G>A、c.912+...     

苯丙酮尿症儿童脑部磁共振成像与临床生化的相关性

目的探讨苯丙酮尿症（PKU）患儿临床及生化与MRI异常改变的关系,评价常规MRI在PKU脑部病变中的价值。方法经临床生化证实为PKU患儿12例。其中4例为新生儿筛查证实,其后接受正规低苯丙氨酸（Phe）饮食治疗;8例未经任何治疗。12例均接受1.5TMRI扫描仪头部检查,应用T2WI、T1WI序列,且对T2WI上异常高信号进行分级,与智商（IQ）、血Phe质量浓度进行相关分析。结果未经治疗的PKU患儿均表现为脑白质T2WI异常高信号,呈斑片状、对称性分布,见于顶枕部脑室周白质。代表白质病变严重程度的MRI分级与血Phe质量浓度（r=-0.537 P〉0.05）及IQ（r=-0.279 P〉0.05）无相关性;血Phe质量浓度与IQ值亦无相关性（r=0.412 P〉0.05）。结论PKU患儿IQ低或血Phe高与常规T2WI上的异常范围并不成正比;常规MRI可很好显示PKU脑部病变,能为临床诊断及监控治疗提供帮助。     

Cerebral energy metabolism in phenylketonuria: findings by quantitative In vivo 31P MR spectroscopy

Both severe impairments of brain development in untreated infants and acute reversible neurotoxic effects on brain function are clinical features of phenylketonuria (PKU). For determining whether impairments of cerebral energy metabolism play a role in the pathophysiology of PKU, quantitative in vivo 31P magnetic resonance spectroscopy (MRS) was performed in a supratentorial voxel of 11 adult PKU patients and controls. Peak areas of inorganic phosphate; phosphocreatine; alpha-, beta-, and gamma-ATP; NAD; phosphomonoesters; phosphodiesters; and a broad phospholipid signal were converted to millimolar concentrations. Mg2+, pH, ADP, the phosphorylation potential, and the relative velocity of oxidative metabolism V/Vmax were derived. Clinical evaluation included mutation analysis, neurologic investigation, intelligence testing, magnetic resonance imaging, and concurrent plasma and brain phenylalanine (Phe), the last by 1H-MRS. Phe loading was performed in five patients with an oral dose of 100 mg/kg body wt L-Phe monitored by spectral EEG analysis. Under steady-state conditions, 31P-MRS revealed normal values for ATP, phosphocreatine, NAD, phosphomonoesters, phosphodiesters, Mg2+, and pH in PKU. ADP (+11%) and the phosphorylation potential (+22%) were increased. Peak areas of inorganic phosphate (-22%) and phospholipid (-8%) were decreased. ADP correlated with concurrent plasma (r = 0.65) and brain (r = 0.55) Phe. During the Phe load, blood Phe levels increased steeply. EEG revealed slowing of background activity. The phosphorylation potential decreased, whereas ADP and V/Vmax increased. In vivo 31P-MRS demonstrated subtle abnormalities of cerebral energy metabolism in PKU in steady-state conditions that were accentuated by a Phe load, indicating a link between Phe neurotoxicity and imbalances of cerebral energy metabolism.     

Differential diagnosis of increased phenylalanine blood level in infancy. Results of the German collaborative study on phenylketonuria (PKU)/hyperphenylalaninemia (HPA)

Between 1978 and 1984 165 children with elevated Phe blood levels in newborn screening were included in a German multicentric study. The differential diagnosis, comprising Phe concentrations in the blood under a tetrahydrobiopterin (BH4) load (30 mg BH4), determination of pterins in the urine and dihydropteridin reductase (DHPR) in erythrocytes, resulted in two patients with a 6-pyruvoyltetrahydrobiopterin synthase (PTPS) deficiency. Those patients with a defect in the apoenzyme phenylalanine hydroxylase (PH) were treated with a low Phe diet, when the Phe blood concentrations exceeded 10 mg/dl under an adapted formula (n = 154). At the age of six months, in 155 infants a protein challenge containing 180 mg Phe/kg body weight for three days was performed, followed by a fourth day with 5 mg Phe/kg. Corresponding to the US Collaborative Study [19] 3 types of response were chosen according to the course of the Phe blood level under the challenge (n = 145). Type I response (n = 112) shows a continuous increase of the Phe more than 20 mg/dl even under the Phe restriction at day 4. Type II response (n = 14) shows also increasing Phe blood levels above 20 mg/dl, followed by a spontaneous decrease below 20 mg/dl still during the high Phe challenge and even lower at the fourth day with low Phe intake. Type III response (n = 19) had only a small increase of the Phe blood concentration, mostly below 15 mg/dl during the whole challenge period.(ABSTRACT TRUNCATED AT 250 WORDS)     

Maternal hyperphenylalaninaemia as a cause of microcephaly and mental retardation

We attempted to evaluate the role of maternal hyperphenylalaninaemia (HPA) as an isolated cause of mental retardation and microcephaly in children. This transversal study observed the plasma phenylalanine from mothers of 161 children with mental retardation and/or microcephaly of unknown origin. In this sample, we found two women with previously undiagnosed HPA, a frequency (2/161) higher than expected for our general population (1:12 500) ( p < 0.001). We concluded that the plasma phenylalanine levels should be determined during preconceptional evaluation of every woman of reproductive age that already has had a child affected either by mental retardation or microcephaly of unknown cause. It is particularly significant where women currently having their pregnancies have not been screened for phenylketonuria as newborns, as happens in most developing countries.     

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目的探讨四氢生物蝶呤反应性苯丙氨酸羟化酶(PAH)缺乏症这一新的临床变异型在高苯丙氨酸血症(HPA)中的发生率,并进一步了解其PAH基因突变类型。方法2001年1月至2004年12月,上海第二医科大学附属新华医院收治的106例中位年龄2个月(0.5～59个月)的HPA患儿纳入研究。所有患儿做辅酶的羟生物蝶呤(BH4,20mg/kg)或联合血苯丙氨酸(Phe,100mg/kg)负荷试验、尿蝶呤谱分析及红细胞二氢蝶啶还原酶活性(DHPR)测定。以口服BH4后24h内血Phe浓度下降30%以上且排除BH4缺乏症为诊断标准。对13例BH4反应性PAH缺乏症患儿进行PAH基因突变检测。结果106例HPA者中41例(38.7%)为BH4反应性的PAH缺乏症。血Phe浓度在服用BH4前为(816±431)μmol/L,服BH4后24h内降至(267±198)μmol/L,反应下降率(67±19)%。41例尿蝶呤及DHPR活性均正常。106例中轻度HPA(18例)其BH4反应性PAH缺乏症发生率为61.1%(11/18)。13例做PAH基因突变检测,R241C为最多见突变类型(43.8%)。结论61.1%轻度HPA(11/18)及42.4%(28/66)轻度PKU对BH4有较大反应性。BH4负荷试验是该病有效而简便的鉴别诊断方法。     

In vivo proton magnetic resonance spectroscopy in phenylketonuria

In vivo nuclear magnetic resonance spectroscopy permits the non-invasive examination of metabolic characteristics of the human brain in a clinical environment. Methods to detect elevated phenylalanine (Phe) in patients with phenylketonuria (PKU) using difference spectroscopy and to estimate absolute brain Phe concentrations, [Phe]_brain, have been developed. In patients with classical PKU, [Phe]_brain typically varied between 0.14 and 0.78 mmol/l depending upon actual blood Phe concentrations, [Phe]_blood, between 0.47 and 2.30 mmol/l. Dynamic investigations can be used to extract information about Phe transport at the human blood-brain barrier, which may be described by a symmetric Michaelis-Menten model. Carrier saturation and competitive inhibition of the influx of other large neutral amino acids can be expected at blood levels usually found in PKU patients. In single cases of untreated, normal intelligent patients, abnormally low [Phe]_brain h 0.15 mmol/l were observed despite high stationary Phe levels ([Phe]_blood=1.15 - 0.10 mmol/l). Conclusion Significant variations in phenylalanine transport parameters in untreated, normal intelligent patients indicated that blood-brain barrier transport or intracerebral phenylalanine consumption are causative factors for the individual vulnerability to phenylketonuria.     

治疗延迟的苯丙酮尿症患儿脑髓鞘发育延迟与智力发育的研究

目的　应用磁共振成像(MRI)观察苯丙酮尿症(PKU)治疗延迟患儿治疗前后脑髓鞘发育延迟与智商的关系。方法　2 0 0 2～2 0 0 3年中日友好医院确诊经典型治疗延迟PKU患儿1 7例,治疗前后分别进行头颅MRI及智商检查,脑髓鞘发育按Staudt标准对不同年龄阶段患儿1 0个脑区域进行量化评估。智商检测采用Gesell发育量表测定。结果　治疗前所有病例存在脑髓鞘发育延迟,在1 0个脑区域脑髓鞘发育延迟平均发生率为44 . 7% ,主要部位在脑叶和胼胝体,并存在不同程度的智力发育落后,平均智商为44 .2 ;经低苯丙氨酸饮食治疗1年后,1 0个脑区域髓鞘发育延迟平均发生率为3 0 . 6% ,平均智商为60 . 6;治疗前、后脑髓鞘延迟改善有显著性(P <0. 0 1 ) ,平均智商改善有统计学意义(P <0. 0 5) ,且智商改善率与髓鞘延迟改善率间可见部分相关性。结论　治疗延迟的PKU患儿的脑髓鞘发育延迟及智力发育落后发生率较高,经低苯丙氨酸饮食治疗可使其在一定程度有所改善,但不能达到完全正常,提示脑髓鞘发育延迟可能是导致PKU患儿智力发育落后的原因之一。     

Differential diagnosis of hyperphenylalaninaemia by a combined phenylalanine-tetrahydrobiopterin loading test

We describe a new fully reliable method for the differential diagnosis of tetrahydrobiopterin-dependent hyperphenylalaninaemia (HPA). The method comprises the combined phenylalanine (Phe) plus tetrahydrobiopterin (BH₄) oral loading test and enables the selective screening of BH₄ deficiency when pterin analysis is not available or when a clear diagnosis has not been previously made. It should be performed together with the measurement of dihydropteridine reductase (DHPR) activity in blood. The new combined loading test was performed in nine patients with primary HPA, three with classical phenylketonuria (PKU), three with DHPR deficiency, and three with 6-pyruvoyl tetrahydropterin synthase (PTPS) deficiency. Three hours after oral Phe loading (100 mg/kg body weight), synthetic BH₄ was administered orally at doses of either 7.5 or 20 mg/kg body weight. Amino acid (Phe and tyrosine) and pterin (neopterin and biopterin) metabolism and kinetics were analysed. By exploiting the decrease in serum Phe 4 and 8h after administration, a clear response was obtained with the higher BH₄ dose (20 mg/kg body weight), allowing detection of all cases of BH₄ deficiency, as well as differentiation of BH₄ synthesis from regeneration defects. Since DHPR deficient patients who were previously shown to be non-responsive to the simple BH₄ loading test gave a positive response, the combined Phe plus BH₄ loading test can be used as a more reliable tool for the differential diagnosis of HPA in these patients. Moreover, it takes advantage of being performed while patients are on a Phe-restricted diet.     

苯丙酮尿症患儿治疗前后脑白质病变的观察

目的：该研究应用MRI观察晚治苯丙酮尿症(PKU)患者治疗前后脑白质病变。方法：确诊为经典型PKU患者19例,进行低苯丙氨酸(PHE)饮食治疗随诊8～16月,治疗前后分别进行了头颅MRI及智商检查。头颅MRI采用常规矢状面、轴面T1W和轴面T2W扫描,对脑白质T2高信号病变按Thompson6级分级法进行分级并评分。观察比较治疗前后脑白质病变的改变。结果：9例晚治PKU患者头颅MRI均存在脑白质病变,其病变主要表现为侧脑室周围及三角区白质等区域存在孤立性斑片状异常T2高信号,治疗前后的平均MRI脑白质T2高信号分级分别为2.59和1.76,治疗前后MRI分级按分数计算,差异有显著性(P<0.01),治疗后T2高信号等级改善。19例均存在不同程度的智力发育落后,在智商改善与T2高信号等级改善可见部分一致关系。血PHE浓度与脑白质病变间有关。结论：晚治PKU患者脑白质病变及智力发育落后具高发生率,低苯丙氨酸饮食治疗降低血苯丙氨酸浓度后脑白质病变及智商均有部分改善,提示PKU患者脑白质病变及智力损害是部分可逆的,PKU患者脑白质改变可能是导致晚治PKU患者智能发育障碍的原因之一。     

Magnetic resonance imaging of the brain structures in the posterior fossa in retarded autistic children

Midsagittal magnetic resonance images of the brains of retarded autistic children were compared to those of non-autistic mental retardation patients and controls. We found that the whole brain stem and particularly two of its components (the midbrain and medulla oblongata) were significantly smaller in retarded autistic children and mental retardation cases than in control children. The pons area was significantly smaller in mental retardation cases as compared to control children but did not differ between autistic and control children. Moreover, there was no difference in the brain stem between retarded autistic children and mental retardation cases. We also noted no difference in the cerebellar vermis area among retarded autistic children, mental retardation cases and control children. The ratio of the midbrain to posterior fossa area was significantly smaller only in autistic patients. Although the significance of these results is unknown, further examination of autistic children with a normal IQ is necessary.