Pregnancy in phenylketonuria: dietary treatment aimed at normalising maternal plasma phenylalanine concentration.

The transport characteristics of the placenta, which favour higher phenylalanine concentrations in the fetus than in the mother, and regression data of head circumference at birth against phenylalanine concentration at conception in maternal phenylketonuria (PKU), suggest that treatment of maternal PKU should ideally aim to maintain plasma phenylalanine concentration within the normal range throughout pregnancy. A patient with classical PKU was treated from before conception by aiming to maintain plasma phenylalanine concentration within the range 50-150 mumol/l and tyrosine within the range 60-90 mumol/l. The diet was supplemented with phenylalanine-free amino acids (100-180 g/day) and tyrosine (0-5 g/day). Plasma amino acid concentrations were monitored weekly by amino acid analyser. Dietary phenylalanine intake ranged from 6 mg/kg/day at conception to 30 mg/kg/day at delivery. Normal weight gain and fetal growth were maintained throughout the pregnancy. A normal baby was born at term with a head circumference of 35.5 cm; at 1 year of age no abnormality is detectable. These results show that with careful monitoring and compliance it is possible, and may be advisable, to maintain plasma phenylalanine concentration within the normal range in the management of PKU pregnancy.     

Phenylalanine hydroxylase expression in liver of a fetus with phenylketonuria

The expression and activity of phenylalanine hydroxylase was studied in the liver of a fetus aborted after prenatal diagnosis of phenylketonuria. No phenylalanine hydroxylase enzymatic activity or immunoreactive protein was detectable in the PKU liver specimen, though both enzymatic activity and immunoreactive protein were detectable in control specimens of similar gestational age. Phenylalanine hydroxylase messenger RNA of normal size was present in the PKU fetal liver at normal abundance. These results confirm the genetic diagnosis of PKU in this fetus and indicate that the mutations in this fetus affect translation or stability of the phenylalanine hydroxylase protein.     

The international collaborative study of maternal phenylketonuria: status report 1994

Neonatal screening for phenylketonuria (PKU) has created a problem as females with PKU are reaching child-bearing age. Surveys have revealed that maternal phenylalanine blood concentrations greater than 1200 μmol/l are associated with fetal microcephaly, congenital heart defects and intrauterine growth retardation. It is estimated that as many as 3000 hyperphenylalaninemic females may be at risk of producing these fetal abnormalities. To examine this problem, the international maternal PKU collaborative study was developed to evaluate the efficacy of a phenylalanine-restricted diet in reducing fetal morbidity. Preliminary findings have indicated that phenylalanine restriction should begin before conception for females with PKU planning a pregnancy. Dietary control should maintain maternal blood phenylalanine levels between 120 and 360 μmol/l and should provide adequate energy, protein, vitamin and mineral intake. Pregnant hyperphenylalaninemic females who achieved metabolic control after conception or by the 10th week of pregnancy had a better offspring outcome than anticipated. The results of 402 pregnancies are reviewed.     

Baby of a phenylketonuric mother: Inferences drawn from a single case

Reports on pregnancy in phenylketonuric women are rare, but fetal brain damage has been well documented and attributed to the mother''s biochemical disturbance. Reports on fetal health after the treatment of phenylketonuria (PKU) in pregnancy are even rarer. Since the treatment of PKU girls is often stopped or relaxed at various prepubertal ages, pregnancy may occur soon in apparently normal girls who have high phenylalanine levels and PKU. In view of the scarcity of information, implications are cautiously suggested from the experience gained of one case. More information is needed urgently, not about the effects of PKU alone, but also of hyperphenylalaninaemia. The present case suggests that it is possible for a fetus to escape malformation, brain damage, and growth failure if maternal dietary treatment is good from about the 20th week of gestation. It would be unwise, however, to accept this finding as holding true for all cases.     

幼儿发育落后间断抽搐8个月

该文报道1 例因发育落后及癫癎而诊断为母性苯丙酮尿症(phenylketonuria, PKU)的患儿。患儿男,1 岁8 个月时就诊,发育落后,1 岁出现癫癎,毛发黑,头围小,发育商为43,脑MRI 扫描显示白质髓鞘化发育落后,双侧侧脑室增宽,枕骨大孔狭窄。染色体核型正常,血液氨基酸、酯酰肉碱谱及尿液有机酸正常。家族史调查发现患儿母亲自幼智力落后,学习困难,毛发色泽发黄,26 岁结婚,婚前常规检查未见异常。患儿母亲于28 岁来院检查,血液氨基酸分析发现血液苯丙氨酸显著增高(916.54 μmol/L,正常值20~120 μmol/L),苯丙氨酸羟化酶(PAH)基因c.611A>G(p.Y204C)纯合突变,为PAH 缺陷导致的PKU 患者。患儿为c.611A>G杂合突变携带者,血液苯丙氨酸正常。患儿父亲健康,PAH 基因未检出突变。建议对于不明原因智力障碍的患儿需进行详细的家族史调查,对智力障碍的父母更需进行详细的临床及代谢分析,以发现亲代疾病导致的儿童脑损害,如母性PKU。     

Prenatal diagnosis of cystic fibrosis in a Turkish family.

Prenatal diagnosis of cystic fibrosis (CF) was made in a Turkish family whose first born child was diagnosed at necropsy as having CF. Two consecutive pregnancies followed. The fetus of the second pregnancy was diagnosed as having CF by the microvillar enzyme assay and was aborted. The diagnosis was verified by the DNA polymerase chain reaction analysis using chorionic villi from the abortus. In the third pregnancy, amniocentesis was performed in the 17th week, and KM19 polymorphism linked to CF was used to assess the status of the fetus. Since the fetus was determined to be a carrier, the family was advised to continue with the pregnancy.     

Maternal phenylketonuria: comparison of two treated full term pregnancies

This case report documents the fetal outcome of two full term pregnancies in a patient with phenylketonuria (PKU). She was treated with a low phenylalanine diet preceeding and during both pregnancies. During her first full term pregnancy she was not able to maintain the rigid diet, and this pregnancy resulted in the delivery of a growth-retarded, microcephalic boy. In her second pregnancy the patient maintained the diet until her delivery at full term. Maternal blood phenylalanine levels remained with two exceptions below 600 mol/l throughout pregnancy and an infant of normal weight and head circumference was born.Abbreviations PKU phenylketonuria - BPD biparietal diameter     

Maternal phenylketonuria: report from the United Kingdom Registry 1978-97.

BACKGROUND: The effects of maternal phenylalanine on the fetus include facial dysmorphism, microcephaly, intrauterine growth retardation, developmental delay, and congenital heart disease. AIMS: To evaluate the impact of phenylalanine restricted diet in pregnant women with phenylketonuria (PKU) on their offspring. METHODS: Data on virtually all pregnancies of women with PKU in the United Kingdom between 1978 and 1997 were reported to the United Kingdom PKU Registry. The effect of the use and timing in relation to pregnancy of a phenylalanine restricted diet on birth weight, birth head circumference, the presence or absence of congenital heart disease (CHD), 4 year developmental quotient, and 8 year intelligence quotient were examined. RESULTS: A total of 228 pregnancies resulted in live births (seven twin pregnancies were excluded). In 110 (50%), diet started before conception. For this group mean (SD) birth weight was 3160 (612) g, birth head circumference 33.6 (1.9) cm, 4 year DQ 108.9 (13.2), 8 year IQ 103.4 (15.6), and incidence of CHD was 2.4%. In comparison, for those born where treatment was started during pregnancy (n = 91), birth weight was 2818 (711) g, birth head circumference 32.7 (2.0) cm, 4 year DQ 96.8 (15.0), 8 year IQ 86.5 (13.0), and incidence of CHD was 17%. Month-by-month regression analyses suggested that metabolic control by 12-16 weeks gestation had most influence on outcome. CONCLUSIONS: Many features of the maternal PKU syndrome are preventable by starting a phenylalanine restricted diet. Women with PKU and their carers must be aware of the risks and should start the diet before conception, or as soon after as possible.     

Maternal phenylketonuria: report from the United Kingdom Registry 1978-97

Background: The effects of maternal phenylalanine on the fetus include facial dysmorphism, microcephaly, intrauterine growth retardation, developmental delay, and congenital heart disease. Aims: To evaluate the impact of phenylalanine restricted diet in pregnant women with phenylketonuria (PKU) on their offspring. Methods: Data on virtually all pregnancies of women with PKU in the United Kingdom between 1978 and 1997 were reported to the United Kingdom PKU Registry. The effect of the use and timing in relation to pregnancy of a phenylalanine restricted diet on birth weight, birth head circumference, the presence or absence of congenital heart disease (CHD), 4 year developmental quotient, and 8 year intelligence quotient were examined. Results: A total of 228 pregnancies resulted in live births (seven twin pregnancies were excluded). In 110 (50%), diet started before conception. For this group mean (SD) birth weight was 3160 (612) g, birth head circumference 33.6 (1.9) cm, 4 year DQ 108.9 (13.2), 8 year IQ 103.4 (15.6), and incidence of CHD was 2.4%. In comparison, for those born where treatment was started during pregnancy (n = 91), birth weight was 2818 (711) g, birth head circumference 32.7 (2.0) cm, 4 year DQ 96.8 (15.0), 8 year IQ 86.5 (13.0), and incidence of CHD was 17%. Month-by-month regression analyses suggested that metabolic control by 12–16 weeks gestation had most influence on outcome. Conclusions: Many features of the maternal PKU syndrome are preventable by starting a phenylalanine restricted diet. Women with PKU and their carers must be aware of the risks and should start the diet before conception, or as soon after as possible.     

Three-year audit of the hyperphenylalaninaemia/phenylketonuria spectrum in Victoria

AIMS: To determine the prevalence, the types and severity of hyperphenylalaninaemia (including phenylketonuria (PKU)) in Victoria and to report on a new treatment modality of PKU. METHODS: We reviewed the medical records of all patients diagnosed with high blood phenylalanine levels by newborn screening between November 2001 and October 2004. RESULTS: We identified 17 newborn babies with high levels of blood phenylalanine (total samples: 190,835). Dihydrobiopterin reductase deficiency was excluded in all babies. Five babies had persistent phenylalanine levels of 200-300, and do not receive any dietary or pharmaceutical therapy. One baby was diagnosed as having pyruvoyl tetrahydro-pterin synthase deficiency. Following reports of tetrahydrobiopterin (BH(4))-responsive PKU, we have performed a BH(4) load (20 mg/kg, 6R-5,6,7,8-tetrahydro-L-biopetrin dehydrochloride; Schricks Laboratories, Jona, Switzerland) in 10 newborn babies with PKU (one baby with a phenylalanine level of 2600 micromol/L was started on diet without prior load). Three babies had a significant response to BH(4) (>35% decrease in phenylalanine level). Protein restriction (1.2 g/kg/day) and introduction of phenylalanine-free formula, in addition to BH(4) treatment, were necessary in one patient. The other patients maintain good metabolic control with BH(4) treatment only (at approximately 11 mg/kg/day) and an intake of 2-3 g protein per day. Of the nine babies who are on a full PKU diet, three have high phenylalanine tolerance (consistently >40 mg/kg/day). CONCLUSION: There is a spectrum of severity of hyperphenylalaninaemia in the population. The detection of BH(4)-responsive PKU patients offers them a less restrictive dietary regimen and an improved quality of life, and may enable near normal life-style in adolescence.     

Screening programme for phenylketonuria in the Gaza Strip: evaluation and recommendations

Phenylketonruia (PKU) is an inherited metabolic disorder that results in progressive mental retardation. PKU is a paradigm of a disease that can be identified by proper screening of newborns and medical follow-up in order to prevent serious complications. The present study was designed to evaluate the Palestinian national screening programme for PKU in the Gaza Strip. Data about the screening of PKU in the Gaza Strip were obtained from the records of the healthcare centers of the Palestinian Ministry of Health (MOH) during the year 2000. In addition, PKU patients and families were interviewed. The results showed that the prevalence of PKU in the Gaza Strip varied considerably between the different regions with an overall prevalence of 6.35/100,000, while the maximum prevalence of 28.3/100,000 occurred in the rural areas. Coverage of PKU testing in the Gaza Strip is limited to about 35.3 per cent of the total newborns, who are delivered and receive health care at the government clinics. Among those newborns delivered at the government clinics, the percentage of PKU screening is about 87.8 per cent. However, PKU testing is not carried out at UNRWA clinics where about two-thirds of newborn deliveries take place. On average, 61 per cent of PKU testing is made in the infant's second week, ranging between 11 and 17 days, and the remaining (39 per cent) are tested thereafter. Approximately 60 per cent of PKU patients had consanguine parents (first cousins), while 7.7 per cent had no consanguinity. Only 43.1 per cent of PKU patients were fed on the specialized low phenylalanine milk. An inverse correlation was reported between the use of low phenylalanine milk and age. A total of 35.4 per cent of the PKU patients were regularly monitored by blood tests each month, 47.7 per cent had not been tested for the previous year. It was concluded that the PKU screening programme has to be improved, the screening methods should be reviewed, and the screening coverage should include all the newborns in the Gaza Strip.     

Phenylalanine control and family functioning in early-treated phenylketonuria

The association between effective metabolic control and patients' intelligence test performance and behavior in phenylketonuria (PKU) has been demonstrated frequently. The present study reexamined this relationship in a population of 41 young children with early-treated PKU, and added a dimension of family investigation to determine relationships between dietary phenylalanine control and patient functioning, family functioning and phenylalanine control, and family functioning and patient functioning. Significant correlations were found between concurrent phenylalanine control and patients' intelligence test scores, and lifetime phenylalanine control and patients' social competence. Parent-report measures of family psychological adjustment, stress, interaction, and socioeconomic status showed no significant association with children's dietary phenylalanine control. Family cohesion and adaptability correlated positively with patients' cognitive performance. Results support a policy of diet continuation in PKU, and suggest that family interaction patterns influence patient functioning. Longitudinal study of family factors in PKU is indicated.     

Predictors of mean phenylalanine levels during the first five years of life in patients with phenylketonuria who were treated early

We studied the relationship between plasma phenylalanine level at first diagnostic visit, country of origin of the mother, birth cohort, child clinic, sex, and social class on the one hand and mean plasma phenylalanine levels in the first five years of life on the other hand in patients with phenylketonuria (PKU) who were treated early. The study population consisted of 131 early treated patients with PKU born during the period from September 1st, 1974 to December 31st, 1988 in The Netherlands. Plasma phenylalanine levels from first diagnostic visit (usually before the age of three weeks) up until the fifth birthday were registered. For each patient the mean phenylalanine level during that period was calculated. Our results suggest that 1) it is more difficult to maintain low phenylalamine levels in patients with a more severe form of PKU, 2) in recent years paediatricians have treated their patients with a stricter diet, 3) there are differences in perception between paediatricians of different clinics as to what levels are acceptable, and 4) treatment of patients from non-Dutch mothers is more difficult than treatment of patients with Dutch mothers.     

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。     

Children with Inborn Errors of Phenylalanine Metabolism: Prognosis and Phenylalanine Tolerance

ABSTRACT. Twenty-three children, who were detected by neonatal PKU screening, were followed for 8-18 years in one paediatric centre. Dietary treatment was started if the blood phenylalanine level exceeded 0.72 mmolA. All 23 infants were initially given a low phenylalanine diet. The growth and development rates of the children did not differ significantly from those in a reference population, although one child had mild mental retardation and another had a short attention span. Fourteen children were still on a strict phenylalanine-restricted diet on their last follow-up (at 8-18 years of age). In nine children who were initially put on a low phenylalanine diet, it was possible to normalize the diet between 1/2 and 10 years of age, while maintaining the blood phenylalanine levels between 0.25 and 0.72 mmol/1. It seems likely that those of our patients who markedly increased their phenylalanine tolerance during childhood had a regulatory mutation of the phenylalanine hydroxylase system. A continuous reevaluation of each child treated with a low phenylalanine diet reduces the use of unnecessarily restricted diets.     

Children with inborn errors of phenylalanine metabolism: prognosis and phenylalanine tolerance

Twenty-three children, who were detected by neonatal PKU screening, were followed for 8-18 years in one paediatric centre. Dietary treatment was started if the blood phenylalanine level exceeded 0.72 mmol/l. All 23 infants were initially given a low phenylalanine diet. The growth and development rates of the children did not differ significantly from those in a reference population, although one child had mild mental retardation and another had a short attention span. Fourteen children were still on a strict phenylalanine-restricted diet on their last follow-up (at 8-18 years of age). In nine children who were initially put on a low phenylalanine diet, it was possible to normalize the diet between 1/2 and 10 years of age, while maintaining the blood phenylalanine levels between 0.25 and 0.72 mmol/l. It seems likely that those of our patients who markedly increased their phenylalanine tolerance during childhood had a regulatory mutation of the phenylalanine hydroxylase system. A continuous reevaluation of each child treated with a low phenylalanine diet reduces the use of unnecessarily restricted diets.     

Prenatal Diagnosis of Duchenne Muscular Dystrophy (DMD) by the Polymerase Chain Reaction (PCR)

The diagnosis of Duchenne muscular dystrophy (DMD) has been drastically improved by recent advances in DNA analysis. The Southern blot hybridization using the cDNA 8 probe and the restriction enzyme Hind III was conducted in a gravida and her family in blood samples. The diagnosis revealed partial gene deletions in both the gravida and the DMD-affected second child. The prenatal diagnosis was performed by studying the PCR (polymerase chain reaction) for target DNAs of exons 48 and 51 that correspond with cDNA 8 probe. In the affected child, the 506 bp band at exon 48 was detected but 388 bp at exon 51 was missing. On the other hand, both the 506 bp band at exon 48 and the 388 bp band at exon 51 were detected in the cultured amniotic cells. Thus, the fetus was determined to be not affected.     

Protein metabolism in phenylketonuria and Lesch-Nyhan syndrome

Animal and in vitro studies have implicated decreased protein synthesis in the pathogenesis of tissue damage in phenylketonuria (PKU) and of growth failure in Lesch-Nyhan syndrome. Protein turnover was measured in vivo in ten young adult subjects with classical PKU, two subjects with hyperphenylalaninemia, and three children with Lesch-Nyhan syndrome using techniques based on continuous infusions of [13C]leucine and, in Lesch-Nyhan subjects, [2H5]phenylalanine. The PKU subjects had various degrees of dietary phenylalanine restriction and plasma phenylalanine levels at the time of study ranged from 450-1540 mumol/L (mean 1106). Plasma phenylalanine in the two hyperphenylalaninemic subjects was 533 and 402 mumol/L. Rates of protein synthesis in all PKU subjects (mean 3.71 g/kg/24 h, range 2.68-5.10, [13C]leucine as tracer) were in a range similar to or above control values (mean 2.97, range 2.78-3.22, n = 6), as were rates of protein catabolism (PKU mean 4.23 g/kg/24 h, range 3.15-5.45; controls 3.64, 3.50-3.91). Protein turnover values in hyperphenylalaninemia were also similar to those in controls. With [13C]leucine as tracer, both mean protein synthesis and catabolism values in Lesch-Nyhan subjects (mean 4.80 and 5.64 g/kg/24 h, respectively) were higher than values in control children matched for protein intake (synthesis 4.32 +/- 0.74 (SD) and catabolism 4.85 +/- 0.57 (g/kg/24 h, n = 5). Similar results were obtained in Lesch-Nyhan subjects using [2H5]phenylalanine as tracer. These results suggest that protein turnover is not decreased in either PKU or Lesch-Nyhan syndrome. This conclusion is inconsistent with the hypothesis that tissue damage in PKU results from impaired protein synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)     

New England Maternal PKU Project: prospective study of untreated and treated pregnancies and their outcomes

Four women with classic phenylketonuria (blood phenylalanine greater than 1200 mumol/L) were given a phenylalanine-restricted diet; three also received L-tyrosine supplements. Biochemical measures of nutrition were normal except for iron deficiency anemia, and in one woman folate deficiency. One pregnancy in which treatment began before conception and another treated from 8 weeks gestation, both with blood phenylalanine levels maintained at 120 to 730 mumol/L, resulted in normal newborn infants whose postnatal growth and development have also been normal. A third pregnancy, treated from 6 gestational weeks, was marked by poor dietary compliance until the middle of the second trimester; fetal microcephaly was identified by ultrasonography at 28 weeks but not at 21 weeks. The child has microcephaly and motor delay. The fourth pregnancy, not treated until the third trimester, produced a child with microcephaly, mental retardation, hyperactivity, and neurologic deficits. It is likely that fetal damage from maternal phenylketonuria can be largely and perhaps entirely prevented by dietary therapy, but therapy must begin before conception for the best chance of a normal infant.     

先天性肾上腺皮质增生症21-羟化酶缺陷的产前诊断一例

目的　探讨先天性肾上腺皮质增生症 2 1 羟化酶缺陷的产前诊断方法。方法　运用Southern杂交、单链构象多态性分析和人工酶切位点分析的方法检测突变 ,对先天性肾上腺皮质增生症 2 1 羟化酶缺陷先证者 (男 ,3岁 )及其父母进行DNA诊断 ,并于其母亲第 5次妊娠 16周时抽取其羊水进行羊水细胞诊断。结果　先证者存在缺失突变与内含子 2第 6 5 6剪切突变 ,父母各携带其一。羊水细胞未检出两种突变 ,判断胎儿正常。胎儿娩出后发育良好 ,实验室检查正常 ,证实了产前诊断结果。结论　羊水细胞DNA分析是先天性肾上腺皮质增生症 2 1 羟化酶缺陷的产前诊断的可靠方法。