Neurocognitive functioning in adults with phenylketonuria: Report of a 10-year follow-up

BACKGROUND

The long-term prognosis of early treated phenylketonuria (PKU) is still under discussion. Aim of this controlled long-term study was to assess the neurological and neuropsychological outcome in adult patients with early-treated PKU.

METHODS

We investigated 35 patients with early-treated classical PKU aged 29 to 51 years (mean age 41 years) and 18 healthy controls matched for age and socioeconomic status. Patients and controls were assessed for their intelligence quotient (IQ), attention and information-processing abilities. Magnetic resonance imaging (MRI) of the brain was performed in all patients. Neuropsychological assessments and MRI were repeated at a five-year and a ten-year follow-up.

RESULTS

In the entire interval IQ, information processing and attention of patients and controls remained constant. At both follow-up assessment times the IQ scores were significantly lower in patients compared to controls. Older adult patients (> 42 years) showed poorer information processing and attention at both assessment times compared to young adult patients (< 42 years) and controls. IQ, information processing and attention showed no correlation to imaging results. IQ, however, was significantly correlated to blood phenylalanine (Phe) levels in patients´ childhood and adolescence, and Phe levels had been higher in the adolescent years of older adult patients.

CONCLUSIONS

Cognitive performance in adult patients with early-treated PKU does not seem to deteriorate in a ten-year interval. Neuropsychological assessment in adults with PKU revealed neurocognitive impairment particularly in older adult patients. This seems to refer to an early relaxation of diet that was recommended when the older patients were adolescents. Results indicate a benefit of dietary control during adolescence in PKU.

Molecular genetics and diagnosis of phenylketonuria: state of the art

Detection of individuals with phenylketonuria (PKU), an autosomal recessively inherited disorder in phenylalanine degradation, is straightforward and efficient due to newborn screening programs. A recent introduction of the pharmacological treatment option emerged rapid development of molecular testing. However, variants responsible for PKU do not all suppress enzyme activity to the same extent. A spectrum of over 850 variants, gives rise to a continuum of hyperphenylalaninemia from very mild, requiring no intervention, to severe classical PKU, requiring urgent intervention. Locus-specific and genotypes database are today an invaluable resource of information for more efficient classification and management of patients. The high-tech molecular methods allow patients' genotype to be obtained in a few days, especially if each laboratory develops a panel for the most frequent variants in the corresponding population.

Recommendations for the nutrition management of phenylalanine hydroxylase deficiency

The effectiveness of a phenylalanine-restricted diet to improve the outcome of individuals with phenylalanine hydroxylase deficiency (OMIM no. 261600) has been recognized since the first patients were treated 60 years ago. However, the treatment regime is complex, costly, and often difficult to maintain for the long term. Improvements and refinements in the diet for phenylalanine hydroxylase deficiency have been made over the years, and adjunctive therapies have proven to be successful for certain patients. Yet evidence-based guidelines for managing phenylalanine hydroxylase deficiency, optimizing outcomes, and addressing all available therapies are lacking. Thus, recommendations for nutrition management were developed using evidence from peer-reviewed publications, gray literature, and consensus surveys. The areas investigated included choice of appropriate medical foods, integration of adjunctive therapies, treatment during pregnancy, monitoring of nutritional and clinical markers, prevention of nutrient deficiencies, providing of access to care, and compliance strategies. This process has not only provided assessment and refinement of current nutrition management and monitoring recommendations but also charted a direction for future studies. This document serves as a companion to the concurrently published American College of Medical Genetics and Genomics guideline for the medical treatment of phenylalanine hydroxylase deficiency.

Undiagnosed phenylketonuria in parents of phenylketonuric patients, is it worthwhile to be checked?

In our phenylketonuria (PKU) cohort of 120 patients, we uncovered a couple of cases of undiagnosed mild phenylketonuria (mPKU)/hyperphenylalaninemia (mHPA) in maternal parents of the PKU cohort. This finding prompted us to evaluate the risk of either mild phenylketonuria or mild hyperphenylalaninemia in the parent population whose children were diagnosed with hyperphenylalaninemia (HPA). Taking into account the phenylalanine hydroxylase (PAH) mutation carrier frequency and the PAH mild mutation rate, we estimated that the prevalence of the parental mPKU/mHPA varied widely, from 1/74 in Turkey to 1/708 in Lithuania. The benefits of the parental detection procedure described here are the prevention of further maternal PKU syndrome, the follow-up of the newly detected patients and the accuracy of the genetic counseling provided to these families. This very simple procedure should be incorporated into neonatal PKU management of the hospitals in countries where a routine systematic neonatal screening is operational.

Phenylketonuria

Phenylketonuria is the most prevalent disorder caused by an inborn error in aminoacid metabolism. It results from mutations in the phenylalanine hydroxylase gene. Phenotypes can vary from a very mild increase in blood phenylalanine concentrations to a severe classic phenotype with pronounced hyperphenylalaninaemia, which, if untreated, results in profound and irreversible mental disability. Neonatal screening programmes identify individuals with phenylketonuria. The initiation of a phenylalanine-restricted diet very soon after birth prevents most of the neuropsychological complications. However, the diet is difficult to maintain and compliance is often poor, especially in adolescents, young adults, and pregnant women. Tetrahydrobiopterin stimulates phenylalanine hydroxylase activity in about 20% of patients, and in those patients serves as a useful adjunct to the phenylalanine-restricted diet because it increases phenylalanine tolerance and allows some dietary freedom. Possible future treatments include enzyme substitution with phenylalanine ammonia lyase, which degrades phenylalanine, and gene therapy to restore phenylalanine hydroxylase activity.

Cost effectiveness of establishing a neonatal screening programme for phenylketonuria in Libya

BACKGROUND

Inborn errors of metabolism (IEM) are a significant cause of morbidity and mortality in North Africa and the Middle East. With the evident success of neighbouring countries in initiating neonatal screening for IEM, the Libyan Authorities are now considering introducing neonatal screening for phenylketonuria (PKU) in Libya in the first instance, with the prospect of expanding the programme to cover other IEM in the future.

OBJECTIVE

To estimate the cost effectiveness of neonatal screening for PKU compared with no neonatal screening in Libya.

METHODS

A decision model was constructed to estimate the cost effectiveness of neonatal screening for PKU, from the perspective of Libyan society. Healthcare resource use and other input parameters were based on expert opinion.

RESULTS

The expected discounted cost to Libyan society of screening over 15 years and managing ∼374 patients with detected PKU over their lifetime was estimated to be $US213.6 (95% CI 211.9, 214.3) million (year 2007-8 values). The current expected discounted cost of managing these same PKU patients over their lifetime as a result of not screening was estimated to be $US321.2 (95% CI 318.0, 322.7) million. Hence, screening would save Libyan society $US107.6 (95% CI 105.5, 109.1) million over the lifetime of PKU patients and lead to an additional 6947 life-years (95% CI 6837, 7056). The expected cost per undiscounted life-year gained was estimated to be -$US15,500 (95% CI -16,600, 1100). There would be a 90% return on investment in the screening programme since society would gain $US1.9 for every $US1 invested. Probabilistic sensitivity analysis demonstrated that the screening programme has a 0.95 probability of being cost effective even at a willingness-to-pay threshold of $US4000 per life-year gained.

CONCLUSIONS

Within the model's limitations, neonatal screening for PKU appears to offer Libyan society a strategy that is cost effective compared with no neonatal screening.

[Diagnosis, treatment and long-term following up of 223 patients with hyperphenylalaninemia detected by neonatal screening programs]

OBJECTIVE

To investigate the incidence of hyperphenylalaninemia (HPA) caused by different etiologic factors in China and the relationship between the phenylalanine and mental development of patients with HPAs who were diagnosed by neonatal screening and early treated.

METHODS

Two hundred and twenty-three patients with HPA detected by neonatal screening programs were refered to us at the age of (41 +/- 27) days after birth. The differential diagnosis was performed by BH(4) (20 mg/kg) loading test, urinary pterin analysis and dihydropteridine reductase (DHPR) activity determination respectively. The control of phenylalanine (Phe) metabolism, growth and mental development were evaluated in all treated patients. Related gene mutation analysis was performed in some patients

RESULTS

One hundred and twenty-nine of 223 patients (57.8%) were diagnosed as phenylalanine hydroxylase deficiency (PAHD), 64 patients (28.7%) as BH(4) responsive PAHD, 30 patients (13.5%) as 6-pyruvoyl tetrahydropterin synthase deficiency (PTSD). One hundred and forty-nine patients were followed at age of 4 m - 2 y in our clinic. The 136 of 149 patients were treated according to different etiology at the age of 1.6 m (0.5 - 3.5 m) after birth. Thirteen patients were followed up without the need for treatment. All patients had normal growth development. One hundred and eight (79.4%) of 136 treated patients had normal mental development. The negative correlation (r = -0.439, P < 0.01) between IQ and average Phe levels were observed in 58 patients. Twenty-eight patients were able to go to primary school or even university. Nine kinds of PTS gene mutations were found in 9 cases with PTSD, among which 286G-->A and 259C-->T were most commonly seen, accounting for 45%. Seven kinds of PAH gene mutations were found in 13 cases with BH(4) responsive PAHD with the R241C (43.8%) mutation being the most frequent one.

CONCLUSION

The differential diagnosis should be quickly made in all HPA patients detected by neonatal screening. Near 80% patients early treated had normal mental development. The good control of blood Phe level is a key factor for mental development.

Low therapeutic threshold for hepatocyte replacement in murine phenylketonuria

Phenylalanine homeostasis in mammals is primarily controlled by liver phenylalanine hydroxylase (PAH) activity. Inherited PAH deficiency (phenylketonuria or PKU) leads to hyperphenylalaninemia in both mice and humans. A low level of residual liver PAH activity ensures near-normal dietary protein tolerance with normal serum phenylalanine level, but the precise threshold for normal phenylalanine clearance is unknown. We employed hepatocyte transplantation under selective growth conditions to investigate the minimal number of PAH-expressing hepatocytes necessary to prevent hyperphenylalaninemia in mice. Serum phenylalanine levels remained normal in mice exhibiting nearly complete liver repopulation with PAH-deficient hepatocytes (<5% residual wild-type liver PAH activity). Conversely, transplantation of PAH-positive hepatocytes into PAH-deficient Pah(enu2) mice, a model of human PKU, yielded a significant decrease in serum phenylalanine (<700 muM) when liver repopulation exceeded approximately 5%. These data suggest that restoration of phenylalanine homeostasis requires PAH activity in only a minority of hepatocytes.

[Screening for phenylketonuria in 726,998 neonates in Zhejiang Province]

OBJECTIVE

To analyze the results of screening for neonatal phenylketonuria (PKU) in Zhejiang Province.

METHODS

The screening for neonatal PKU was conducted among 726,998 newborns in Zhejiang Province. Heel prick blood specimens were collected around 72 h after birth with 6 intakes of high protein milk and the specimens were dried on S and S903 filter papers. Phenylalanine (Phe) levels were determined quantitatively with Perkin Elmer Neonatal Fluorometric PKU kits.

RESULTS

Among 726,998 newborns, elevated blood Phe levels were found in 152 infants. They were all recalled for serum amino acid analysis and 32 were confirmed to have PKU with 19 males and 13 females. The earliest time of confirmation was 16 d and latest was 105 d with the median of 32 d.

CONCLUSION

The data shows that the detection rate of screening for neonatal phenylketonuria in Zhejiang Province was 1/22,718.

Avaliação do programa de prevenção e promoção da saúde de fenilcetonúricos

OBJETIVO: Avaliar os resultados de ações preventivas e de promoção à saúde institucionalizadas para crianças fenilcetonúricas. MÉTODOS: Foram avaliados os resultados alcançados pelo Programa de Triagem Neonatal, do Estado do Paraná, entre os fenilcetonúricos, no período de 1996 a 2001. Foram investigados dados socioeconômicos e aplicado instrumento de medição da função motora grossa para determinar as habilidades motoras de 32 crianças fenilcetonúricas com diagnóstico e tratamento precoces. Optou-se pela utilização do coeficiente de correlação de Pearson para verificar a relação entre a variável de interesse (escore motor) e as demais variáveis quantitativas (nível médio de fenilalanina pós-tratamento, escolaridade do pai e da mãe, idade da criança no início do tratamento e renda familiar). RESULTADOS: Dentre as crianças avaliadas, 93,7% apresentaram desenvolvimento de acordo com os parâmetros de normalidade referenciados na literatura. O tratamento foi iniciado no primeiro mês em 71,9% dos casos de fenilcetonúria. A pesquisa socioeconômica registrou 39,5% de pais com instrução até o quarto ano escolar. Foi encontrada correlação significativa entre o escore motor da criança e a escolaridade dos pais (N=32), e entre o escore motor e a precocidade do tratamento (N=27). CONCLUSÕES: Os resultados evidenciaram a alta efetividade do programa avaliado. A baixa escolaridade dos pais e sua relação com o escore motor ressaltam a importância do apoio aos pais na dietoterapia. A relação encontrada entre o escore motor e o início do tratamento confirma a necessidade da adesão imediata ao programa. A inexistência na literatura de outros estudos de avaliação dificulta a generalização dos resultados.

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.

[An eighteen-year study on phenylketonuria]

A study on phenylketonuria (PKU) has been carried out in China-Japan Friendship Hospital since 1984. The results revealed that: (1) Totally 603 patients with PKU were diagnosed and treated in the hospital from October 1984 to September 2002. Among which 136 cases were identified by neonatal screening and treated within 3 months. One hundred and ninety-five cases were treated when the children were 3-12 months of age. Another 272 PKU children were diagnosed when they were more than 1 year old. All of these late-treated cases had some signs and symptoms of PKU. Mental retardation was found in 467 cases and various patterns of seizures in 119 cases. After treatment with low-phenylalanine diet, the follow-up for early-treated patients revealed that their physical and mental developments were normal. In late-treated patients, abnormal behaviour was significantly improved and their developmental quotient were elevated. Prenatal gene diagnosis of PKU risk foetus in 22 PKU families was successfully performed. (2) Urinary pterins obtained from 369 HPA patients were measured by HPLC. Twenty two patients with BH4 deficiency have been recognized. Six single base mutations were detected in 18 unrelated northern Chinese BH4 deficiency families, and the mutations at nucleotides 259C-->T and 286G-->A were common mutations. Eighteen BH4 deficient patients were treated with BH4, L-dopa and 5-hydroxytryptophan, and the results were satisfactory. (3) The abnormal rate of EEG was high in untreated patients with PKU, mainly showing epileptiform discharges and partly showing background activity abnormality. The most frequent finding was patchy areas of increased signal intensity in white matter on MRI in the brain of PKU patients, while delayed myelination and brain agenesis were often detected. After dietary treatment, follow-ups with EEG and MRI revealed that the abnormalities were decreased significantly. (4) The relationship between genotype and intellectual phenotype was examined in 29 late-treated patients with classical PKU. It was found that the genotype of 22 patients were compatible with intellectual phenotype and not well matched in 7 cases. The result indicate that the genotype was well matched with intellectual phenotype in classical PKU patients.

Newborn PKU screening in Turkey: at present and organization for future

At present, pkenylketonuria screening is a national child health program in Turkey which is carried out collaboratively by the Ministry of Health and three University Children's Hospitals in Ankara, Istanbul and Izmir. Since 1986 the number of cities included in the screening program has gradually increased, now and it covers all the metropolises the country. A total of 383 babies were found with persistent hyperphenylalaninemia (1:4,172) among 1,605,582 babies screened by the Guthrie test at the Hacettepe Screening Center in Ankara. By taking into account pretreatment phenylalanine levels and phenlyalanine tolerances at five years of age, the numbers of classical and mild-moderate phenylketonuria and mild hyperphenylalaninemia cases were 216, 102 and 58, respectively. The major problems encountered in the screening program and in management of the detected cases were unsatisfactory sample collection, early discharge from maternity hospitals, difficulties in reaching some detected cases, and noncompliance with dietary therapy due to illiterate parents or to lack of social insurance. To screen and treat all newborns for phenylketonuria and to include at least hypothyroidism in the screening program, there is a need for a more disciplinary intersectoral approach than exists at present.

[A cost-benefit evaluation of neonatal screening for phenylketonuria and congenital hypothyroidism]

OBJECTIVE

In order to make the best use of health care resources, to achieve the maximal social and economic benefits and to lay a foundation for popularizing neonatal screening for phenylketonuria (PKU) and congenital hypothyroidism (CH), a cost-benefit analysis of the screening program was conducted.

METHODS

Cost for and benefit gained from screening were calculated according to the average incidence of two diseases recommended by the Ministry of Health, mean charge for neonatal screening, sampling extraction of medical history and data published in national economic statistics.

RESULTS

The cost of neonatal screening, treatment for PKU with low phenylalanine milk powder and follow up, the total add up to 128 793 Yuan However the direct and indirect financial benefits is 481 263 Yuan, ratio of cost to benefit was 1:3.7. The cost of neonatal screening for CH is 129 175 Yuan. However the financial benefits including the money saved in treatment, nursing care, special education and the loss of income avoided is 468 470 Yuan, ratio of cost to benefit was 1:3.6.

CONCLUSION

Neonatal screening for PKU and CH in this country reflects a better economic and social benefit and merits further popularization.

Maternal phenylketonuria syndrome: congenital heart defects, microcephaly, and developmental outcomes

OBJECTIVE

A cohort of women with phenylketonuria (PKU) were selected to explore the impact of phenylalanine (Phe) levels and other factors on congenital heart defects (CHDs), microcephaly, and development of their offspring.

STUDY DESIGN

Three hundred fifty-four women with PKU were followed up weekly with diet records, blood Phe levels, and sonograms obtained at 18 to 20 and 32 weeks' gestation. At birth, 413 offspring were examined and followed up at 6 months and annually by means of Bayley Mental Developmental Index and Psychomotor Developmental Index tests at 1 and 2 years. The women had Wechsler Adult Intelligence Scales and DNA testing.

RESULTS

Thirty-one offspring had CHDs; of these, 17 also had microcephaly. Mean Phe levels at 4 to 8 weeks' gestation predicted CHDs (P <.0001). An infant with a CHD had a 3-fold risk of having microcephaly when the mother had higher Phe levels (P =.02). The Bayley Mental Developmental Index and Psychomotor Developmental Index scores correlated with both CHDs (P =.037 and.0015, respectively) and microcephaly (P =.0001 for both). No direct relationship to the PKU mutation was found.

CONCLUSION

None of the women whose offspring had CHDs had blood Phe levels in control during the first 8 weeks of gestation. Women with PKU need to be well controlled on a low-phenylalanine diet before conception and throughout pregnancy.

Prepregnancy testing for single-gene disorders by polar body analysis

Preventive measures for single-gene disorders are currently based on carrier screening in pregnancy and prenatal diagnosis. Although this has been extremely effective for preventing new cases of common inherited conditions, the major limitation is still termination of 25% of wanted pregnancies following detection of affected fetuses. To overcome this important problem, we developed a method for prepregnancy genetic testing that involves DNA analysis of the first and second polar bodies, which are extruded during maturation and fertilization of oocytes. We offered this option to 28 couples at risk for having children with single-gene disorders. Fifty clinical cycles were performed from these patients for the following conditions: 20 for cystic fibrosis, 18 for thalassemia, 6 for sickle cell disease, 2 each for Gaucher disease and LCHAD (long-chain 3-hydroxyacyl-COA dehydrogenase deficiency), and 1 each for hemophilia B and phenylketonuria. Oocytes obtained from these patients using in vitro fertilization procedures (IVF) were tested by a sequential multiplex nested PCR analysis of the first and second polar body to detect the gene involved simultaneously with linked polymorphic markers. A total of 191 of 399 oocytes with predicted genotype were mutation free and preselected for fertilization and transfer. In all but three cycles, one to three unaffected embryos with predicted unaffected genotypes were transferred, resulting in 20 pregnancies, from which 19 healthy children have been born. The follow-up analysis of embryos resulting from oocytes with predicted affected genotype, confirmed the diagnosis in 97% of cases, demonstrating the reliability of prepregnancy diagnosis of single-gene defects by polar body analysis.

Rationale for the German recommendations for phenylalanine level control in phenylketonuria 1997

Treatment of hyperphenylalaninaemias due to phenylalanine hydroxylase deficiency with a low phenylalanine (Phe) diet is highly successful in preventing neurological impairment and mental retardation. There is consensus that, for an optimal outcome, treatment should start as early as possible, and that strict blood Phe level control is of primary importance during the first years of life, but for adolescent and adult patients international treatment recommendations show a great variability. A working party of the German Working Group for Metabolic Diseases has evaluated research results on IQ data, speech development, behavioural problems, educational progress, neuropsychological results, electroencephalography, magnetic resonance imaging, and clinical neurology. Based on the actual knowledge, recommendations were formulated with regard to indication of treatment, differential diagnosis, and Phe level control during different age periods. The development of the early-and-strictly-treated patient in middle and late adulthood still remains to be investigated. Therefore, the recommendations should be regarded as provisional and subject to future research. Efficient treatment of phenylketonuria has to go beyond recommendations for blood Phe level control and must include adequate dietary training, medical as well as psychological counselling of the patient and his family, and a protocol for monitoring outcome.

CONCLUSIONS

Early-and-strictly-treated patients with phenylketonuria show an almost normal development. During the first 10 years treatment should aim at blood Phenylalanine levels between 40 and 240 micromol/L. After the age of 10, blood phenylalanine level control can be gradually relaxed. For reasons of possible unknown late sequelae, all patients should be followed up life-long.

[Neonatal screening in Denmark. Status and future perspectives]

In Denmark, the Faroe Islands, and Greenland, comprehensive screening of newborns for phenylketonuria and congenital hypothyroidism has been carried out for 20 years. The screening programme has detected 98 and 356 patients, respectively, corresponding to incidences of 1:12,000 and 1:3,400. The future savings on health care expenditures resulting from one year of neonatal screening are estimated to be 196 million DKK in present day value, which is 28 times higher than the cost of screening. The screening samples are stored in a biobank, which is used in diagnosis of congenital diseases and infant deaths and for development of future screening methods. It is desirable to expand the existing screening programme to include a range of rare inherited metabolic diseases, which collectively are frequent. This is realistic with the advent of tandem mass spectrometry, which allows cost-effective simultaneous screening for a group of inborn errors of metabolism.

[Programs of systematic screening in neonatology. Pharmaco-economic aspects]

Systematic neonatal screening offers many advantages for the patients, its family and the community. The Genetic center of the University Hospital of Liège provides neonatal screening for the following diseases: phenylketonuria, congenital hypothyroidy, cystic fibrosis, alpha-1-antitrypsin, adrenal hyperplasia and biotinidase deficiency. On economical grounds, it is clear that the organisation of neonatal screening costs less to the community than the cost of the disease if diagnosis is made too late as to allow an alleviation, or even a total recovery, of the symptomatology.

Neonatal screening: current trends and quality control in the United Kingdom

Neonatal screening for phenylketonuria (PKU) and congenital hypothyroidism (CHT) is universal across the UK using heel prick blood collected at 6-14 days of age. Additional programmes for sickle cell disorders, cystic fibrosis, Duchenne muscular dystrophy and galactosaemia are provided in some areas. The number of inherited metabolic disorders (IMDs) has greatly increased since the introduction of PKU screening, and there have been major advances in treatment, e.g. organ transplantation, drug therapy. Recent developments in technology have expanded the possibilities for screening using the heel prick blood specimen, particularly the application of tandem mass spectrometry. There is a case for introducing tandem mass spectrometry, limited to clearly defined diseases where specificity is adequate and there are satisfactory diagnostic tests. Any change in newborn screening to a much broader group of disorders must be carefully introduced and monitored preferably as a pilot study. A key component of a laboratory screening service is quality control. There are well established UK programmes for PKU and CHT. Consideration of the needs for other disorders is now an important priority.

[The routine sampling procedure for PKU should be changed. Venous puncture is less painful than heel lancing]

All newborns in Sweden are screened for phenylketonuria (PKU), among other things, blood usually being sampled by heel lancing. Because it is unnecessarily painful, however, this form of sampling in newborns has recently been questioned. There is reason to recommend sampling from a dorsal hand vein as the method of choice for PKU screening purposes.

Audit of neonatal screening programme for phenylketonuria and congenital hypothyroidism

The performance of the neonatal screening programme was audited against clinical standards in the Bath clinical area from 1 April 1994 to 31 March 1996. The standards and policy were agreed by local service provider representatives of the screening and were audited, using laboratory and child health computer systems and medical records. Two annual reports were produced with recommendations for improvement communicated to representatives of the service. Thus the first audit loop has been completed. The audit shows that the coverage of the service is excellent, with all eligible babies being offered screening; those with congenital hypothyroidism or phenylketonuria receive appropriate treatment by the 28 day standard. The process works extremely well, although areas for improvement have been identified, to increase the efficiency of the service. It is concluded that an effective and efficient audit cycle can be established, to monitor and improve the performance of the neonatal screening service.

Milk-induced hypoalgesia in human newborns

OBJECTIVE

To determine whether milk and its components reduce crying in newborns during and after blood collection for phenylketonuria evaluation.

METHODOLOGY

Seventy-two normal newborns ingested 2 mL of milk (Similac), Ross Special Formula, fat, protein, lactose, sucrose, or water for the 2 minutes preceding blood collection via heel lance. Crying duration during and for the 3 minutes after the procedure was determined by scorers who were blind to the ingestive substance.

RESULTS

Sucrose and Similac each reduced crying during the blood collection procedure. Sucrose, fat, protein, and Ross Special Formula were effective during the 3-minute recovery period. Neither water nor lactose were effective during or after blood collection.

CONCLUSION

Milk and some of its components are antinociceptive in human newborns. Based on previous studies, reduced crying during and after painful stimulation may be mediated through endogenous opioids. These findings are of potential clinical significance: natural protective mechanisms, normally engaged during suckling, may safely and noninvasively be activated to reduce newborn crying to painful stimulation.

The impact of early obstetric discharge on newborn health care

The impetus for shorter hospital stay of mother and newborn infant after delivery is based on economic constraints and parental preference. Earlier published studies did not demonstrate any increase in morbidity rate with shorter stay, but these studies were limited by methodologic flaws and biases that limited the validity and generalizability of the conclusions. More recent studies showed that readmission rates increased with shorter stay and that the severity of illness of readmitted infants may have increased. In addition, the interpretation of current newborn screening tests may not be applicable when performed prior to early discharge. In light of recent changes in neonatal hospital length of stay, a careful review and update of current guidelines and practices for newborn care are required.

An audit of the organisation of neonatal screening for phenylketonuria and congenital hypothyroidism in the Northern Region

BACKGROUND

The objectives of the study were to identify whether all districts in the Northern Region had a system in place to ensure that all resident babies were being screened for phenylketonuria and congenital hypothyroidism and to identify potential delays which could influence whether a result was available on all residents before 28 days of age.

METHODS

Lead professionals involved in the screening programmes were interviewed in 1993 in all 16 districts. Recommendations for improving the service were made to each district. Six months later a follow up telephone interview with the doctor involved in the screening programmes was undertaken to identify the changes that had been made in the service.

RESULTS

In 1993 three districts made no attempt to match neonatal screening results to birth notifications. Of the 13 districts that undertook matching, two districts did no further checks to identify babies without a result and five districts undertook a check on a monthly basis only. Only six districts were, therefore, found to have a timely fail-safe system for checking that results were available for resident babies. In 1994, following recommendations to improve the timeliness and completeness of the screening programmes, all districts except two had improved their fail-safe systems.

CONCLUSION

This multi-disciplinary regional audit resulted in organisational improvements to the neonatal metabolic screening programmes in the Northern Region.

Maternal phenylketonuria: a metabolic teratogen

The maternal phenylketonuria (PKU) syndrome refers to the teratogenic effects of PKU during pregnancy. These effects include mental retardation, microcephaly, congenital heart disease, and intrauterine growth retardation. In untreated pregnancies wherein the mother has classic PKU with a blood phenylalanine level > or = 1,200 microM (20 mg/dl), the frequencies of these abnormalities in offspring are exceedingly high, approaching 75-90% for microcephaly and mental retardation and 15% for congenital heart disease. There is a dose response relationship with progressively lower frequencies of these abnormalities at lower phenylalanine levels, both in the pregnancies of women with variants of PKU and in treated classic PKU pregnancies. The pathogenesis of this syndrome is unknown; it may be related to inhibition by phenylalanine of large neutral amino acid transport across the placenta or to direct toxicity of phenylalanine and/or a phenylalanine metabolite in certain fetal organs. A mouse model for PKU now exists, and studies of maternal PKU in this model are in progress. The treatment of maternal PKU consists of biochemical control through a phenylalanine restricted diet during pregnancy. The best results are obtained with diet initiation before conception or no later than the earliest weeks of pregnancy. Women with PKU and their families require much psychosocial support to meet the strict requirements of a maternal PKU pregnancy, including compliance with a difficult diet. With such compliance, however, it seems that bearing normal or near normal offspring is possible.

[Maternal hyperphenylalaninemia in a population of healty Czech women. 18 years' experience with mass screening, diet therapy and metabolic monitoring]

BACKGROUND

Elevated phenylalanine levels in maternal blood (hyperphenylalaninaemia) during pregnancy damages the developing foetal tissues. Early detection of pregnant women with hyperphenylalaninaemia and adherence to a low phenylalanine diet already before conception and throughout pregnancy can prevent this damage. The objective of the investigation are results achieved screening and strict monitoring of low phenylalanine dietetic treatment in detected pregnant women of the Prague population.

METHODS AND RESULTS

186 350 healthy women of the Prague population were examined by the chromatographic screening test in a venous blood sample during their first visit in a maternity welfare centre and 22 positive cases were detected (incidence 1:8470). In 86% mild, persistent or benign forms of phenylketonuria were involved. Nineteen patients were treated by a low phenylalanine diet and the phenylalanine tolerance was monitored as well as the nitrogen balance, amino acids in serum and urine, protein markers, trace elements, vitamins, lipids, the body mass index-BMI, changes of body weight after introduction of the dietetic treatment and treatment during pregnancy. A significant increase of the phenylalanine tolerance by 20 to 200% was found, mostly in the second half of pregnancy and reduced values of serum and urinary selenium. The decrease of body weight when the diet was introduced and the increment during pregnancy correlated with the BMI value. In the other investigated parameters no significant deviations were found.

CONCLUSION

Fifteen healthy children with normal psychomotor development delivered by 12 mothers with hyperphenylalaninaemia provide evidence of the effectiveness of prenatal screening for hyperphenylalaninaemia during pregnancy.

Newborn screening for certain treatable inborn errors of metabolism in Alexandria

The study was conducted on two groups of newborn infants: Group A; a random sample of 3000 infants attending different Health offices in Alexandria for BCG vaccination. Their ages ranged from 5-120 days with a mean age of 39.9 days. Group B; included all the infants born to high risk families attending the clinic of Human Genetics Department, Medical Research Institute (9 infants; 7 with family history of PKU and 2 with family history of congenital hypothyroidism). Their ages ranged from 7 to 60 days with a mean age of 18 days. The newborn infants of the two groups were screened for three treatable inborn errors of metabolism, phenylketonuria "PKU", galactosemia and congenital hypothyroidism with the aim of early detection and therapy to prevent mental retardation. In group A; one baby with transient hyperphenylalaninemia (HPA) (0.33%) and one presumptive case of galactosemia (0.33%) were found. Initial positive results were found in eleven infants they had high levels of thyroid stimulating hormone (TSH). On reevaluation of nine infants of them they were all euthyroids. In Group B, four infants were detected among the infants of PKU families. After confirmation of these results breast feeding was stopped at once and the infants started their dietary management and were kept on it with follow up and periodic evaluation of the adequacy of treatment.

[20-year national screening for phenylketonuria in The Netherlands. National Guidance Commission PKU]

OBJECTIVE

Evaluation of the Dutch national screening programme for phenylketonuria (PKU).

DESIGN

Descriptive.

SETTING

Nationwide.

METHODS

Data on the screening were obtained from the laboratories, from the registration offices of vaccination and screening results and from the paediatricians to whom infants with positive screening values were referred, during the period from September 1st, 1974 to December 31st, 1993.

RESULTS

During the study period 3,481,738 infants were screened in the Netherlands (99.4% of all live births). The sensitivity of the programme was 98%, the specificity 99.99% and the positive predictive value 50%. The prevalence of PKU varied considerably between regions, e.g. from 1:33,600 in Zuid-Holland to 1:8,250 in Limburg (average in the Netherlands 1:18,000). The percentage of patients treated before the age of 22 days was 84% in the period from 1974 to 1988 and 95% in the period from 1989 to 1993 (p = 0.04). Birth weight in patients with PKU was 141 g (95% confidence interval: 66-216) less than the expected birth weight in the Netherlands. Furthermore, a slight growth retardation occurred in the first three years of life in early treated patients. The percentage of patients following special education was twice as high as in the general population (p < 0.001).

CONCLUSION

The screening procedure for PKU is functioning at a high level. Despite early treatment development of patients with PKU is slightly below normal.

Phenylketonuria screening: effect of early newborn discharge

OBJECTIVE

To determine the percentage of term newborns discharged by 24 hours of life and the actions taken by physicians and institutions to avoid false-negative phenylketonuria (PKU) screens in these infants.

DESIGN

Descriptive cross-sectional survey.

PARTICIPANTS

One hundred forty term nurseries and 157 pediatricians.

SELECTION PROCEDURE

Stratified sampling techniques were used to sample nurseries from the 1992 American Hospital Association guide to provide equal representation of each region of the country. Pediatricians were systematically sampled from a national list of practicing pediatricians supplied by Ross Laboratories to provide equal sampling from each state.

RESULTS

The response rates were 95% (n = 133) for term nurseries and 83% (n = 131) for pediatricians. Twenty-four percent of healthy newborns are discharged by 24 hours of life. Ninety-three percent of nurseries screen all infants for PKU before discharge. In states without laws mandating rescreening, only 48% of institutions that discharge the majority of their infants (> 50%) by 24 hours of life rescreen. Also, in states without rescreening laws, 64% of pediatricians rescreen. The timing of this repeat screen ranges from less than 72 hours of life to 4 weeks. Determining which infants to rescreen varies by practitioner; some rescreen all infants, whereas others rescreen those discharged early. Just more than half of all pediatricians, whether practicing in a state requiring repeat PKU screening, claim to be familiar with the American Academy of Pediatrics recommendations regarding repeated PKU screening of infants discharged by 24 hours of life.

CONCLUSION

Twenty-four percent of term newborns in the United States are discharged by 24 hours of life. Most hospitals screen all infants for PKU before discharge regardless of age. The majority of states do not mandate rescreening; rescreening policies among pediatricians and institutions in those states vary widely. A significant number of infants do not receive repeated screening and are therefore at risk for delayed or missed diagnosis of PKU because of insensitive initial screens. Pediatrician awareness of the need to perform repeated PKU screens on infants discharged by 24 hours is poor.

Nutritional therapy for pregnant women with a metabolic disorder

Nutritional therapy is essential for a normal reproductive outcome in phenylketonuric women. In homocystinuria, fetal outcome is good in women whose disorder is responsive to vitamin B6 therapy and is poor in women whose disorder is unresponsive to therapy. Pregnancy in galactosemia is rare because of the almost universal ovarian dysfunction present in female patients with this disorder. Transplantation of the fertilized ovum is a promising possibility for these women. In women with MSUD, there has been only one case of pregnancy reported to date.

[Screening of newborn infants in Norway for severe metabolic disease]

The objective of neonatal screening for phenylketonuria and congenital hypothyroidism is early diagnosis and initiation of treatment to prevent brain damage and mental retardation. We present the results of the Norwegian national neonatal screening programme for phenylketonuria and congenital hypothyroidism. Screening for phenylketonuria based on serum phenylalanine determinations started in 1967 and covered the whole country in 1978. National screening for congenital hypothyroidism started in 1979. One hundred children with phenylketonuria and 280 children with a strong indication of congenital hypothyroidism have been detected up to 1 October 1994. Screening-related challenges and principles of treatment are discussed.

[Neonatal screening for metabolic diseases--a task without priority in the Norwegian health policy?]

The Norwegian national screening programme for early diagnosis of phenylketonuria and congenital hypothyroidism was established in 1978-79. The organization and implementation of the programme is based on a marginal cost policy profile and has kept almost the same structure throughout the period of national neonatal screening. We focus on practical measures aimed at increasing the quality of the programme, and suggest a health political reconsideration of public preference and financial support for neonatal screening in Norway.

Theory and practice of psychopharmacogenetics

This article attempts to elucidate the theory and practice of psychopharmacogenetics. Eight working models were identified and characterized with a distinct view of risk factors in the host, the pathophysiology of disease, and the strategies for optimum therapy. The biochemical culprits related to adverse drug reaction in each case can be used to identify a risk and thus contribute to prevention research. Since the phenomenology of these uncommon conditions covers a broad spectrum of neuropsychiatric manifestations, the insights they generated might presage a better understanding of the natural history of a wider range of mental disorders associated with genetic vulnerability. The emerging information suggests that psychopharmacogenetics could be defined from clinical perspectives as multidimensional analysis of genes, drugs, and behaviour for the treatment and prevention of psychiatric disorders.