Follow-up study of a nation-wide neonatal metabolic screening program in Japan

A nationwide neonatal sreening program for phenylketonuria (PKU), maple syrup urine disease (MSUD), homocystinuria, histidinemia and galactosemia was started in Japan in 1977. The total number of infants screened had reached 6,311,754 by March, 1982. A follow-up study revealed the incidence of the disease in Japan: 1/108,823 for PKU; 1/450,840 for hyperphenylalaninemia (HPA); 1/1,577,939 for biopterin deficiency; 1/525,980 for MSUD; 1/1,051,959 for homocystinuria; 1/8,371 for histidinemia, and 1/788,969 for galactosemia type 1. The incidences of PKU, HPA, homocystinuria, and galactosemia (type 1) were found to be markedly low in Japan as compared with those in Caucasian countries. There was no great difference in the incidence of MSUD between both. On the other hand, the incidence of histidinemia was higher in Japan.It was found that most of the patients with PKU, HPA, MSUD, homocystinuria, or galactosemia are developing normally due to the early initiation of dietary treatment. These results clearly indicate that the neonatal mass screening program plays a great role in preventing the occurrence of handicapped children.     

Neonatal Mass-Screening for Inborn Errors of Metabolism in Japan

This report describes the results of neonatal mass screening in Japan for PKU, maple syrup urine disease, histidinemia, homocystinuria, galactosemia, inborn errors of urea cycle metabolism and congenital hypothyroidism. The incidence of PKU is low but the incidence of histidinemia is somewhat high compared to that in the United States. Some genetic variants of each of these inborn errors of metabolism such as malignant hyperphenylalaninemia or mild form of MSUD have been detected in the neonatal screening. Clinical values of the screening for each of these in born errors of metabolism are discussed.     

上海地区遗传代谢病的新生儿筛查(英文)

Objectives Inborn errors of metabolism (IEM) has a diverse spectrum and different incidence in different countries, the early diagnosis at presymptomatic stage is imperative to benefic patient from sequelae. Phenylke-tonuria (PKU) / hyperphenylalaninemia (HPA) is the most common metabolism disorder in Shanghai as well as in other regions. The study is to further clarify the incidence of inborn errors of metabolism among newborn in Shanghai. Methods The dried blood spot specimens were collected from near 90 ...     

Experience and Problems of Newborn Mass Screening for Inborn Errors of Metabolism in Japan

A program of newborn mass screening for inborn errors of metabolism has since 1977 been conducted by The Ministry of Health and Welfare in Japan with great success in preventing mental and physical handicaps in children and estimating the incidence of these diseases in our country as follows: phenylketonuria (PKU) 1/78,100 maple syrup urine disease (MSUD) 1/281,200 histidinemia 1/10,600 galactosemia 1/156,200 There are some genetic variants of each of these diseases, PKU, MSUD and others. Circumspection is therefore required in making a diagnosis or selecting a particular method of treatment. When MSUD is suspected, it is necessary to make a definite diagnosis promptly and take therapeutic measures including peritoneal dialysis. The efficacy of low histidine diet in histidinemia is not yet ascertained. Close inquiries should be made about the benefit of such a dietary regimen and the long term prognosis therewith. A screening test for homocystinuria by the detection of blood methionine level is difficult. In cases with high blood methionine level during the neonatal period, it is necessary to differentiate the condition from other disease with high blood methionine. Hepatorenal tyrosinemia appears to be unsuitable for mass screening because of the the unefficacy of low phenylalanine tyrosine diet in some of the patient and the difficulty to differentiate from transient tyrosinemia in normal newborn infants. However, mass-screening is recommendable for Richner-Hanhalt type tyrosinemia which responds well to dietary therapy and which is easy to differentiate from the transient tyrosinemia because of the marked elevation of blood tyrosine.     

Treatment of Inborn Errors of Metabolism

The results of a collaborative study of children treated on newborn mass-screening program in Japan are described. Forty-three cases of PKU, in which the dietary treatment was started between 9 to 35 days of life, were followed up, their ages ranging from 6 months to .6 years. DQ or IQ was found to be within normal range in all cases. As compared with IQ in untreated cases of PKU, an evident effect of early treatment was observed. Two of ten cases of hyperphenylalaninemia were found to be of the malignant type due to a defect in biopterin synthesis. Oral test of tetrahydrobiopterin to decrease of serum phenylalanine was thought to be clinically useful in the differential diagnosis of malignant hyperphenylalaninemia. Eight cases of galactosemia on the dietary treatment were followed up, their ages ranging from 6 months to 8 years. DQ or IQ was found to be within normal range in 7 of 8 cases. Five cases of maple syrup urine disease on the dietary treatment were followed up. DQ was within normal range in 3 of 5 cases. One died of sepsis at 39 days of life, and the other one showed lower IQ. A simple method for detecting hyperammonemia was described. The method requires only one drop of blood and takes only 15 minutes to complete. This new method is considered to be useful for routine, low-cost mass-screening of newborn infants for hyperammonemia. Newborn mass-screening program for phenylketonuria (PKU), maple syrup urine disease (MSUD), homocystinuria, histidinemia and galactosemia has been going on in Japan with the support of the Ministry of Health and Welfare since 1977. In parallel with this program, the collaborative study of children treated for these disorders has been started to evaluate the effects of early treatment. This investigation was made in eleven medical centers listed in Table 1 all over Japan. This paper describes a brief summary of the collaborative study.     

Development of Histidinemic Patients: Follow-Up Study of Five Cases with Neuropsychological Symptoms

We described the general clinical course of histidinemia in a previous report. Here, we report on five patients having particular problems in the developmental aspects. Case 1 was found to have histidinemia at the age of 3 years during a clinical survey of the nature of his neurological symptoms. He has been followed up for seven years. He developed poorly in verbal expression. Case II was detected by newborn mass screening. The psychomotor development was apparently normal, but in detail, the development of fine motor and cognitive function was insufficient during the follow-up period. Consequently, a developmental lag in visual perception, visual motor perception and spatial perception were noted in this case. Cases III, IV and V were each 3 years old, and were also diagnosed as histidinemic by newborn mass screening test; scanty attachment and various kinds of autistic behavior were noted during their clinical course. These five cases were clinically different from other non-symptomatic patients with histidinemia. It is important to study the pathogenesis of such psychomotor abnormalities from the viewpoint of psychological care for the children.     

四氢生物蝶呤反应性苯丙氨酸羟化酶缺乏症

目的：四氢生物蝶呤(BH4)可以使BH4缺乏症病人的血液苯丙氨酸水平正常化,但是对苯丙酮酸尿症(PKU)病人无效。最近在新生儿PKU筛查中发现了对BH4有反应的轻度PKU患者。本研究将探讨BH4和苯丙氨酸羟化酶(PAH)基因突变在对BH4有反应的轻度PKU和轻度高苯丙酸血症(HPA)患者中的作用。方法：对经新生儿PKU筛查中发现的生物蝶呤代谢正常的轻度HPA患者,进行单次(10mg/kg)、4次、1周[20 mg/(kg·d)]的BH4口服负荷试验及长期BH4治疗,评估其对BH4口服负荷试验的反应性。结果：在单剂量BH4口服负荷试验中,典型PKU患者的血苯丙氨酸水平没有降低。在单剂量BH4口服负荷试验中血苯丙氨酸水平下降超过20%的患者,在4次BH4口服负荷试验中下降亦超过20%。1周BH4负荷试验确认在单剂量和4次BH4负荷试验中表现出弱反应性的病人对BH4有反应。许多患轻度PKU和轻度HPA且有R241C基因位点的病人,都对BH4治疗有反应。在无BH4反应性的典型PKU病人中未发现R241C、P407S和A373T基因突变。结论：1周BH4负荷试验用于诊断BH4反应性PAH缺乏症最为有效。等位基因R241C、P407S和A373T与轻度HPA和轻度PKU病人具有H4反应性有关。BH4治疗是针对轻度HPA和轻度PKU的一种新颖、有效的药物治疗,有望代替限制苯丙氨酸饮食的方法。     

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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。     

Biochemical screening in mental retardation

Biochemical screening of 3000 mentally retarded individuals led to the detection of 64 cases with metabolic defects comprising phenylketonuria, homocystimuria, histidinemia, Hartnup disease, Hurler syndrome, Hunter syndrome, hydroxy-prolinemia, Tay-Sach disease, kinky hair disease and Lesch-Nyhan syndrome. The largest number of cases of PKU reported from India originate from Karnataka state. The biochemical procedures found useful and reliable in screening for metabolic defects among the mentally retarded, as well as the newborn cases have been indicated. These include tests for detecting errors of metabolism in aminoacids, mucopolysaccharides, lipids and reducing substances.     

Zinc status of untreated histidinemic children

In order to study zinc status in histidinemia, serum and hair zinc concentrations were measured in 40 untreated children with histidinemia (age 2 months-5 years). In 20 children (greater than 2 years of age) zinc content and carbonic anhydrase activity of erythrocytes and urinary excretion of zinc were also studied. The amount of zinc excreted was elevated in histidinemic children and showed a positive correlation with the urinary histidine concentration (gamma = 0.57, p less than 0.005). The means of serum zinc concentration, erythrocyte zinc concentration, and erythrocyte carbonic anhydrase activity were all similar in the histidinemic and the control children. Hair zinc concentration of histidinemic children was compared with that of controls of five different age groups: less than 5 months, 5-18 months, 18 months-2 years, 2-4 years, and 4-5 years. In all of these age groups, hair zinc content was similar. The incidence of low-hair-zinc level (less than 80 micrograms/g) in histidinemic children greater than 5 months of age (9 of 34) was significantly higher than in controls (18 of 180, p less than 0.05). The observation suggested the possibility that untreated histidinemia may cause chronic mild zinc deficiency in some histidinemic children.     

青岛市苯丙氨酸羟化酶缺乏症患儿基因突变分析

目的探讨青岛市苯丙氨酸羟化酶(phenylalanine hydroxylase,PAH)缺乏症患儿的基因突变特点,为青岛市PAH缺乏症的产前诊断、治疗提供科学参考依据。方法对经青岛市新生儿疾病筛查确诊的44例PAH缺乏症患儿,应用第二代高通量测序及多重连接酶探针依赖扩增(multi-ligase probe dependent amplification,MLPA)技术进行基因分析,检测患儿基因突变位点,应用Sanger测序对其父母的PAH基因相应突变位点进行检测并验证。根据患儿血苯丙氨酸浓度,分为经典型苯丙酮尿症、轻度苯丙酮尿症和轻度高苯丙氨酸血症。结果①44例PAH缺乏症患儿PAH基因中均检测到2个突变位点,其中2例为纯合突变,纯合突变的频率为4.6%,所有突变在患儿父母相应突变位点处均能检测到。②44例PAH缺乏症患儿共检测到突变36种,其中c.728G>A突变频率最高(15.9%,14/88),其次是c.1068C>A(10.2%,9/88),再次为c.158G>A(9.1%,8/88)。③21例经典型苯丙酮尿症患儿PAH基因突变19种,其中c.1068C>A突变频率最高(21.4%,9/42),其次是c.728G>A(19.0%,8/42)。10例轻度苯丙酮尿症患儿PAH基因突变14种,其中c.721C>T/722delG突变频率最高(15.0%,3/20),其次为c.1197A>T、c.1301C>A、c.721C>T、c.728G>A(均为10.0%,2/20)。13例轻度高苯丙氨酸血症患儿PAH基因突变17种,其中c.158G>A突变频率最高(26.9%,7/26),其次为c.728G>A(15.4%,4/26)。结论青岛市PAH缺乏症患儿PAH基因突变以复合杂合突变为主,具有明显热点突变(c.728G>A、c.1068C>A、c.158G>A),经典型苯丙酮尿症患儿以c.1068C>A、c.728G>A为主,轻度苯丙酮尿症患儿以c.721C>T/722delG为主,轻度高苯丙氨酸血症患儿以c.158G>A为主。本研究明确了青岛市PAH缺乏症患儿基因的突变类型与特点,为深入开展PAH缺乏症的诊断以及进一步的基因治疗奠定了基础。     

A Chinese family with phenylketonuria and maternal phenylketonuria detected by family screening

A 16-year-old boy with classical phenylketonuria (PKU) and mild mental retardation (IQ 69) was detected by the screening of mentally retarded school children in Taiwan with Guthrie's bacterial inhibition assay. The follow-up family study showed that one of his married elder sisters suffered from borderline mental retardation (IQ 75) and was also diagnozed as a classical case of PKU. She had borne one boy and one girl, both suffering from mild mental retardation, microcephaly, delay in linguistic development and severe growth retardation. This is the first known Chinese family with maternal PKU. To prevent future mental retardation caused by maternal PKU, the simultaneous establishment of a register system with a neonatal screening programe, is indicated for the follow-up of PKU girls, screening of the whole family of newly discovered PKU cases, and to exclude unrecognized maternal PKU in women who have given birth to a microcephalic child.Abbreviations PKU phenylketonuria - WAIS Wechsler adult intelligence scale - CCDI Chinese children development inventory     

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。     

IgA deficiency in children: A clinical study with special reference to intestinal findings

Clinical, immunological, and intestinal studies on 26 children with IgA deficiency in the age range 2 to 16 years are reported. 9 of these children were suffering from autoimmune disease, namely thyroiditis (5), thyrotoxicosis (1), rheumatoid arthritis (2), and probable Sjögren''s syndrome (1). The last-mentioned patient had defective cellular immunity. Altogether 11 patients were subject to recurrent respiratory tract infections. The symptomatology of the remaining patients was variable. In a boy with growth retardation, a chromosome anomaly was found, and endocrinological studies indicated total absence of growth hormone.In 21 patients IgA was undetectable, while 5 had trace amounts of IgA in their sera. IgG was raised in 11 patients, and one patient had low serum IgG. IgM levels were mostly normal. Precipitating antibodies to cow''s milk proteins were present in all but one serum.Small intestinal biopsy was performed on all patients. In 3 cases total villous atrophy was detected and these probably had coeliac disease, though malabsorption symptoms were not always evident. Disaccharidase assay of biopsy specimens revealed 2 cases of isolated lactase deficiency among 8 tested.Results show that the increased incidence of autoimmune disease reported in IgA deficiency in adults also holds true in children; i.e. that there is a raised incidence of coeliac disease with or without symptoms in IgA deficiency.     

Genetic background of hyperphenylalaninemia in Nagasaki,Japan

Phenylketonuria (PKU) and related hyperphenylalaninemia (HPA) are caused by a deficiency in hepatic phenylalanine hydroxylase (PAH). The incidence of PKU in Nagasaki prefecture is higher than that in all parts of Japan (1/15 894 vs 1/120 000). To investigate the genetic background of patients with HPA in Nagasaki prefecture, mutation analysis was done in 14 patients with PKU or mild HPA. Homozygous or compound heterozygous PAH mutations were identified in all the patients. The spectrum of PAH mutations in the cohort was broad and similar to those in all parts of Japan and East Asian countries. R53H is the most common mutation in patients with mild HPA. The present results provide further support for genotype–phenotype correlations in patients with HPA. The high incidence of PKU in Nagasaki, the westernmost part of Japan, might be due to migration of people with PAH mutations from China and Korea, and geographic factors.     

THE INCIDENCE OF PKU IN FINLAND

Guthrie's bacterial inhibition test was applied to 71 135 newborn infants from different parts of Finland. No cases of PKU were diagnosed. In addition, 3 685 mentally retarded patients, mostly idiots and imbeciles, have been screened in Finland with the same method. With two cases of PKU among them, a prevalence of 0.54 per 1 000 is obtained. The incidence of the disease among the newborn is estimated to be less than one per 100 000.     

Newborn screening for phenylketonuria: predictive validity as a function of age

Data from questionnaires were assembled for 109 infants with phenylketonuria (PKU) and 114 control infants to assess the predictive validity of newborn screening for PKU as a function of age. Patients with PKU had values of less than 4 mg/dL in cord blood and in samples from days 1, 2, and 4 through 7. The proportion of patients with PKU expected to fall below screening cutoffs of 2, 4, and 6 mg/dL was predicted for each age range. Using a cutoff of 4 mg/dL, approximately one third of patients with PKU would be missed by a sample taken from the neonate in the first 12 hours of life, and nearly 10% would be missed with a sample from the second 12 hours of life. This study shows that not all patients with PKU will be detected by newborn screening, and that the phenomenon of early nursery discharges must be considered in developing appropriate screening strategies.     

In vivo studies of phenylalanine hydroxylase by phenylalanine breath test: diagnosis of tetrahydrobiopterin-responsive phenylalanine hydroxylase deficiency

Tetrahydrobiopterin (BH4)-responsive phenylalanine hydroxylase (PAH) deficiency is characterized by reduction of blood phenylalanine level after a BH4-loading test. Most cases of BH4-responsive PAH deficiency include mild phenylketonuria (PKU) or mild hyperphenylalaninemia (HPA), but not all patients with mild PKU respond to BH4. We performed the phenylalanine breath test as reliable method to determine the BH4 responsiveness. Phenylalanine breath test quantitatively measures the conversion of L-[1-13C] phenylalanine to 13CO2 and is a noninvasive and rapid test. Twenty Japanese patients with HPA were examined with a dose of 10 mg/kg of 13C-phenylalanine with or without a dose of 10 mg . kg(-1) . d(-1) of BH4 for 3 d. The phenylalanine breath test [cumulative recovery rate (CRR)] could distinguish control subjects (15.4 +/- 1.5%); heterozygotes (10.3 +/- 1.0%); and mild HPA (2.74%), mild PKU (1.13 +/- 0.14%), and classical PKU patients (0.29 +/- 0.14%). The genotypes in mild PKU cases were compound heterozygotes with mild (L52S, R241C, R408Q) and severe mutations, whereas a mild HPA case was homozygote of R241C. CRR correlated inversely with pretreatment phenylalanine levels, indicating the gene dosage effects on PKU. BH4 loading increased CRR from 1.13 +/- 0.14 to 2.95 +/- 1.14% (2.6-fold) in mild PKU and from 2.74 to 7.22% (2.6-fold) in mild HPA. A CRR of 5 to 6% reflected maintenance of appropriate serum phenylalanine level. The phenylalanine breath test is useful for the diagnosis of BH4-responsive PAH deficiency and determination of the optimal dosage of BH4 without increasing blood phenylalanine level.     

Serum Carnitine Level in Phenylketonuric Children under Dietary Control in Greece

ABSTRACT. Although total, free and esterified carnitine blood levels were found to be low (p < 0.001) in phenylketonuric patients under dietary treatment compared to controls, no clinical signs of carnitine deficiency were noticed. Exclusion from the PKU diet of nutrients rich in carnitine has been suggested. Supplementation of the diets with carnitine or preferably enrichment of the PKU formulas with carnitine will rectify the restriction of extrinsic carnitine in PKU dietary treatment.     

Mutation analysis of phenylketonuria in Yamagata prefecture, Japan

BACKGROUND: We have screened 309,914 newborns in Yamagata prefecture, Japan, since 1977 and have detected four patients with phenylketonuria (PKU). We analyzed the phenylalanine hydroxylase (PAH) gene of the four patients to study the genetic background in this area and the genotype-phenotype relationship in these patients. METHODS: Mutations of the PAH gene were screened by denaturing gradient gel electrophoresis analysis and the sequences were determined. RESULTS: Three cases were compound heterozygotes of six different mutations of the PAH gene and the remaining case was a homozygote. Of the six detected mutations, K115fs is novel, whereas the others have been previously detected among Chinese and/or Japanese patients. CONCLUSIONS: The incidence and genetic basis in Yamagata prefecture was similar to that of other parts of Japan. Analysis of the genotype is useful to understand the clinical variation in some families.