The impact of visual media to encourage low protein cooking in inherited metabolic disorders

Background:  The use of educational visual aids is one way to help children with inherited metabolic disorders (IMD) understand and develop a positive attitude towards their low protein diet. However, it is difficult to establish their effectiveness in the clinical setting. The present study aimed to evaluate the impact of a low protein recipe book and accompanying DVD for children with IMD.
Methods:  One hundred and five children (53% female; median age = 6–8 years) with IMD on low protein diets were each given a low protein recipe book and DVD. After 6 months, children and carers were posted a questionnaire asking whether they used these resources; identifying any change in frequency of low protein cooking; and the outcome when preparing recipes.
Results:  One hundred and two questionnaires were returned, representing 105 patients. Seventy percent ( n  = 71) of questionnaires were from carers. Ninety-three percent ( n  = 66) of carers acknowledged receipt of the resource; one-third ( n  = 22) had not watched the DVD and 23% ( n  = 15) had not opened the recipe book; 55% ( n  = 36) had tried the recipes; and 71% ( n  = 47) said the recipe book and/or DVD motivated them to try new recipes. Children were more likely to have watched the DVD (75%; n  = 21/28) and read the recipe book (86%; n  = 24/28) than carers.
Conclusions:  Although a helpful educational tool, just over one-half of respondents had used the resource. Identifying visual media that, by itself, will motivate most families of children with IMD to prepare low protein recipes may be unrealistic. The combined approach of visual aids and 'hands-on' practical experience, such as low protein cooking workshops and individual counselling, may be more beneficial.     

Spectrum and origin of phenylketonuria mutations in Spain

In order to characterize the molecular heterogeneity of phenylalanine hydroxylase deficiencies in the Spanish population, 37 PKU patients were initially screened for 16 known European mutations. For the remaining unidentified alleles, we used a combined strategy based on single strand conformation polymorphism analysis and DNA sequencing. Overall, a total of 15 different mutations were found in our sample, which account for 62% of the total mutant alleles. We also investigated the association between the mutations, haplotypes and variable number of tandem repeats described on the phenylalanine hydroxylase gene. In addition, we analyzed the geographical distribution in Spain of the two most prevalent mutations in our population: IVS10 and I65T.     

Hyperphenylalaninemia due to impaired dihydrobiopterin biosynthesis

A fourteen month-old boy with atypical phenylketonuria was treated with 5-hydroxytryptophan, L-dopa and peripheral aromatic amino acid decarboxylase inhibitor (Ro 4-4602:benserazide). Despite the good control of plasma phenylalanine on a low phenylalanine diet, he had shown no improvement in his development but progressive neurological symptoms, such asiirritability, convulsions and decrease voluntary movement. After beginning neurotransmitter therapy, his irritability disappeared promptly and the other symptoms diminished. He gradually reached his developmental milestones. At two and a half years of age, he had recovered sufficiently to be able to walk freely on treatment with 13 mg/kg/day of 5-hydroxytryptophan, 11 mg/kg/day of L-dopa and 2.7 mg/kg/day of benserazide in combination with slight restriction of phenylalanine intake (100 mg/kg/day).Levels of serotonin and 5-hydroxyindoleacetic acid were low in the patient's CSF. His urinary biopterin (Crithidia factor) excretion was low. An increase in serum biopterin following L-phenylalanine loading was not found. Dihydropteridine reductase activity in his skin fibroblasts was normal. He excreated large amounts of erythro- and threo-neopterins (but only a trace of biopterin) in his urine. After loading with phenylalanine the urinary excretion of neopterins was even more enhanced, but biopterin remained at low levels. These findings indicated that the patient has a dihydrobiopterin synthetase deficiency.     

Sustained attention and inhibition of cognitive interference in treated phenylketonuria: associations with concurrent and lifetime phenylalanine concentrations

Fifty-seven 7-14-year-old early- and continuously treated phenylketonuria (PKU) patients and 65 matched controls performed a sustained attention task. PKU patients with plasma phenylalanine (phe) levels higher than 360 micromol/l at the time of testing exhibited, compared to controls, lower speed of information processing, a lower ability to inhibit task-induced cognitive interference, less consistent performance, and a stronger decrease of performance level over time. Patients with concurrent phe levels lower than 360 micromol/l did not differ from controls and were significantly better than patients with levels higher than 360 micromol/l. Strong relationships were found with task performance for phe levels during the pre-school years and between ages 5 and 7. These correlations were stronger than those between concurrent phe level and task performance. Significant multiple regression models were found with age accounting for the largest proportion of variance of tempo and tempo fluctuation, and lifetime phe levels (particularly phe level between ages 5 and 7) accounting for the largest proportion of variance of the relative number of inhibition errors and its increase over time. Phe level between ages 5 and 7 also contributed significantly to the variance of tempo and tempo fluctuation. Neuropsychological outcome was independent of IQ. The results indicate that strict dietary adherence during these periods is beneficial to attentional control later in life. We suggest that phe levels should be maintained under 360 micromol/l until approximately age 12, when development of attentional control approaches an adult level.     

Fetal Heart Malformations in Experimental Hyperphenylalaninemia in Pregnant Rats

Abstract Sprague-Dawley rats were given L-phenylalanine intraperitoneally from the 8th to 11th day of pregnancy. The hearts of the fetuses were examined on the 21st day of pregnancy. We found that the group given the higher doses of L-phenylalanine had significantly more heart defects than the group given the lower dose and the controls. Ventricular septal defect was found in 80 % of the fetuses with congenital deformities of the heart. [¹⁴C] Leucine uptake by the embryos was significantly lower in the group loaded with L-phenylalanine than in the controls.
The activity of thymidine kinase, one of the rate-limiting enzymes in DNA synthesis, was significantly lower in the brain and heart tissues of the young rats loaded with L-phenylalanine than in the controls.
Thus, when blood levels of phenylalanine are high in early pregnancy, an amino acid imbalance in the embryo occurs during fetal organogenesis. Also, thymidine kinase decreases, which may hinder DNA synthesis. Both of these mechanisms seem to be involved in the higher incidence of fetal heart malformations in maternal phenylketonuria.     

智力低下儿童与苯丙酮尿症杂合子

用血浆phe赦度和Phe／Tyr，Phe^2／Tyr，Phe／LNAA比值．以其中一项或一项以上大于正常（成人或儿童)x 2S为诊断杂合子依据．分析了75例智低原因不明儿童．6例新生儿筛查疑高苯丙是酸血症小儿及部分父母。结果显示有26例儿童(23／75，3/6)符合杂合子诊断，其中10例的父母18人中12人符合杂合子标准。     

Comparison of phenylketonuric and nonphenylketonuric sibs from untreated pregnancies in a mother with phenylketonuria

Two children, one with phenylketonuria (PKU) and the other nonphenylketonuric, from untreated pregnancies in a mother with PKU provided the opportunity to compare the degree of damage from maternal PKU between these genotypically different fetuses. Both the phenylketonuric offspring and her nonphenylketonuric sib were microcephalic at birth and had congenital anomalies, esophageal atresia in the former and congenital dislocation of the hip in the latter. However, the phenylketonuric child also had intrauterine growth retardation while the non-phenylketonuric sib had normal weight and length at birth. Both children are mentally retarded with an IQ below 50 in the phenylketonuric child despite early dietary treatment for PKU and an IQ of 54 in the non-phenylketonuric sib. Both children also have hypoplasia of the corpus callosum and enlarged cerebral ventricles. This experience and review of the literature indicates that the residual liver phenylalanine hydroxylase activity of a nonphenylketonuric fetus offers little or no protection from damage in untreated maternal PKU. Consequently, the outcome in maternal PKU is likely to depend on control of the maternal biochemical abnormalities in the mother regardless of whether the fetus has or does not have PKU. © Wiley-Liss, Inc.     

Comparative multiplex dosage analysis detects whole exon deletions at the phenylalanine hydroxylase locus

We have developed quantitative comparative multiplex dosage analysis to detect altered copy number of regions of the phenylalanine hydroxylase gene. Out of 41 alleles (4% of 1,010 PKU chromosomes) on which a mutation had not been characterized previously, this technique has highlighted two novel mutations: deletions of exon 5 and of exon 6 on a total of eight alleles. Restriction-enzyme digestion of genomic DNA and hybridization to an amplified segment of the phenylalanine hydroxylase (PAH) cDNA probe PAH247 established the size of the deletion in five individuals to be between 700 and 900 bases. We also report somatic mosaicism in the parent of an affected child previously shown to have a deletion spanning exons 5 and 6. Finally, we report a putative duplication of a region encompassing exon 6 in an affected individual.     

Glycomacropeptide in PKU—Does It Live Up to Its Potential?

The use of casein glycomacropeptide (CGMP) as a protein substitute in phenylketonuria (PKU) has grown in popularity. CGMP is derived from κ casein and is a sialic-rich glycophosphopeptide, formed by the action of chymosin during the production of cheese. It comprises 20–25% of total protein in whey products and has key biomodulatory properties. In PKU, the amino acid sequence of CGMP has been adapted by adding the amino acids histidine, leucine, methionine, tyrosine and tryptophan naturally low in CGMP. The use of CGMP compared to mono amino acids (L-AAs) as a protein substitute in the treatment of PKU promises several potential clinical benefits, although any advantage is supported only by evidence from non-PKU conditions or PKU animal models. This review examines if there is sufficient evidence to support the bioactive properties of CGMP leading to physiological benefits when compared to L-AAs in PKU, with a focus on blood phenylalanine control and stability, body composition, growth, bone density, breath odour and palatability.     

Haplotype analysis of the phenylalanine hydroxylase gene in Turkish phenylketonuria families

We have estimated the haplotype distribution of mutant and normal phenylalanine hydroxylase (PAH) alleles for 17 Turkish phenylketonuria (PKU) families: 20 normal and 27 mutated PAH alleles could be identified. Of the latter, the most prevalent were associated with haplotype 6 (29.6%), 1 (18.5%) and 36 (11.1%), while the normal alleles were preferentially associated with haplotype 1 (20%). Of the 19 different haplotypes observed, 5 have not been described previously. The haplotype distribution differed significantly from that of the Northern European population. Two of the eight polymorphic sites were in association with PKU. No deletions of exon sequences were found in the families analysed.