Adult male patient with severe intellectual disability caused by a homozygous mutation in the HNMT gene.

Histamine is involved in various physiological functions like sleep-wake cycle and stress regulation. The histamine N-methyltransferase (HNMT) enzyme is the only pathway for termination of histamine neurotransmission in the central nervous system. Experiments with HNMT knockout mice generated aggressive behaviours and dysregulation of sleep-wake cycles. Recently, seven members of two unrelated consanguineous families have been reported in whom two different missense HNMT mutations were identified. All showed severe intellectual disability, delayed speech development and mild regression from the age of 5 years without, however, any dysmorphisms or congenital abnormality. A diagnosis of mental retardation, autosomal recessive 51 was made. Here, we describe a severely mentally retarded adolescent male born from second cousins with a homozygous mutation in HNMT. His phenotypic profile comprised aggression, delayed speech, autism, sleep disturbances and gastro-intestinal problems. At early age, regression occurred. Treatment with hydroxyzine combined with a histamine-restricted diet resulted in significant general improvement.

Benefits and drawbacks of guanidinoacetic acid as a possible treatment to replenish cerebral creatine in AGAT deficiency.

Arginine-glycine amidinotransferase (AGAT) deficiency is a rare inherited metabolic disorder that severely affects brain bioenergetics. Characterized by mental retardation, language impairment, and behavioral disorders, AGAT deficiency is a treatable condition, where long-term creatine supplementation usually restores brain creatine levels and improves its clinical features. In some cases of AGAT deficiency, creatine treatment might be somewhat limited due to possible shortcomings in performance and transport of creatine to the brain. Guanidinoacetic acid (GAA), a direct metabolic precursor of creatine, has recently been suggested as a possible alternative to creatine to tackle brain creatine levels in experimental medicine. AGAT patients might benefit from oral GAA due to upgraded bioavailability and convenient utilization of the compound, while possible drawbacks (e.g. brain methylation issues, neurotoxicity, and hyperhomocysteinemia) should be accounted as well.

Vitamin D, bone mineral density and risk of fracture in people with intellectual disabilities.

BACKGROUND: People with intellectual disabilities (IDs) have very high rates of osteoporosis and fractures, to which their widespread vitamin D deficiency and other factors could contribute. We aimed to assess in people with IDs previously treated for vitamin D deficiency (1) long-term adherence to vitamin D supplementation and (2) bone mineral density (BMD), as an indicator for risk of fractures, according to vitamin D supplementation and other factors. METHOD: We recorded height, weight, medical, pharmacological, dietary and lifestyle assessment. Blood sample were taken for vitamin D and related analytes. dual-energy X-ray absorptiometry for BMD was performed. RESULTS: Of 51 study participants (mean [standard deviation, SD] age 51.5 [13.6] years, 57% male), 41 (80.4%) were taking vitamin D and 10 were not. Mean [SD] serum vitamin D was 81.3 [21.3] vs. 25.2 [10.2] nmol/L (P < 0.0001), respectively. Thirty-six participants underwent a dual-energy X-ray absorptiometry scan, which showed osteoporosis in 23.7% and osteopenia in 52.6%. Participants on vitamin D had higher BMD than those who were not, a statistically significant difference when confounders (lack of mobility and hypogonadism) were removed. BMD was significantly different according to mobility, particularly in wheelchair users, in whom hip BMD was 33% lower (P < 0.0001) than in participants with normal mobility. Participants still taking vitamin D showed a 6.1% increase in BMD at the spine (P = 0.003) after mean [SD] 7.4 [1.5] years vitamin D treatment. CONCLUSIONS: In people with IDs and previous vitamin D deficiency, BMD increases on long-term vitamin D supplementation. However, additional strategies must be considered for osteoporosis and fracture prevention in this population.

Changes in Energy Intake and Diet Quality during an 18-Month Weight-Management Randomized Controlled Trial in Adults with Intellectual and Developmental Disabilities.

BACKGROUND: Previous research indicates that individuals with intellectual and developmental disabilities (IDDs) are at risk for poor diet quality. OBJECTIVE: The purpose of this secondary analysis was to determine whether two different weight-loss diets affect energy intake, macronutrient intake, and diet quality as measured by the Healthy Eating Index-2010 (HEI-2010) during a 6-month weight-loss period and 12-month weight-management period, and to examine differences in energy intake, macronutrient intake, and HEI-2010 between groups. DESIGN: Overweight/obese adults with IDDs took part in an 18-month randomized controlled trial and were assigned to either an enhanced Stop Light Diet utilizing portion-controlled meals or a conventional diet consisting of reducing energy intake and following the 2010 Dietary Guidelines for Americans. Proxy-assisted 3-day food records were collected at baseline, 6 months, and 18 months, and were analyzed using Nutrition Data System for Research software. HEI-2010 was calculated using the data from Nutrition Data System for Research. PARTICIPANTS/SETTING: The study took place from June 2011 through May 2014 in the greater Kansas City metropolitan area. MAIN OUTCOME MEASURES: This was a secondary analysis of a weight-management intervention for adults with IDDs randomized to an enhanced Stop Light Diet or conventional diet, to examine differences in energy intake, macronutrient intake, and HEI-2010 across time and between groups. STATISTICAL ANALYSES PERFORMED: Independent- and paired-samples t tests and general mixed modeling for repeated measures were performed to examine group differences and changes at baseline, 6 months, and 18 months between the enhanced Stop Light Diet and conventional diet groups. RESULTS: One hundred and forty six participants (57% female, mean±standard deviation age=36.2±12.0 years) were randomized to either the enhanced Stop Light Diet or conventional diet group (77 enhanced Stop Light Diet, 69 conventional diet) and provided data for analysis at baseline, 124 completed the 6-month weight-loss period, and 101 completed the 18-month study. Participants on the enhanced Stop Light Diet diet significantly reduced energy intake at 6 and 18 months (both P<0.001), but those on the conventional diet did not (both P=0.13). However, when accounting for age, sex, race, education level, and support level (mild vs moderate IDD), there was a significant decrease during the 18-month intervention in energy intake for the enhanced Stop Light Diet and conventional diet groups combined (P<0.01 for time effect), but no significant group difference in this change (P=0.39 for group-by-time interaction). There was no significant change in total HEI-2010 score at 6 and 18 months (P=0.05 and P=0.38 for the enhanced Stop Light Diet group; P=0.22 and P=0.17 for the conventional diet group), and no significant group difference at 6 and 18 months (P=0.08 and P=0.42). However, when participants' age, sex, race, education level, and support level were accounted for, mixed modeling indicated a significant increase in total HEI-2010 scores for the enhanced Stop Light Diet and conventional diet groups combined during the 18-month intervention (P=0.01 for time effect). CONCLUSIONS: The results of this study found that after controlling for demographic factors, individuals with IDDs can decrease their energy intake and increase their diet quality, with no significant differences between the enhanced Stop Light Diet and conventional diet groups.

A ketogenic diet rescues hippocampal memory defects in a mouse model of Kabuki syndrome.

Kabuki syndrome is a Mendelian intellectual disability syndrome caused by mutations in either of two genes (KMT2D and KDM6A) involved in chromatin accessibility. We previously showed that an agent that promotes chromatin opening, the histone deacetylase inhibitor (HDACi) AR-42, ameliorates the deficiency of adult neurogenesis in the granule cell layer of the dentate gyrus and rescues hippocampal memory defects in a mouse model of Kabuki syndrome (Kmt2d+/ßGeo). Unlike a drug, a dietary intervention could be quickly transitioned to the clinic. Therefore, we have explored whether treatment with a ketogenic diet could lead to a similar rescue through increased amounts of beta-hydroxybutyrate, an endogenous HDACi. Here, we report that a ketogenic diet in Kmt2d+/ßGeo mice modulates H3ac and H3K4me3 in the granule cell layer, with concomitant rescue of both the neurogenesis defect and hippocampal memory abnormalities seen in Kmt2d+/ßGeo mice; similar effects on neurogenesis were observed on exogenous administration of beta-hydroxybutyrate. These data suggest that dietary modulation of epigenetic modifications through elevation of beta-hydroxybutyrate may provide a feasible strategy to treat the intellectual disability seen in Kabuki syndrome and related disorders.

Protective effects of dietary supplementation with natural ω-3 polyunsaturated fatty acids on the visual acuity of school-age children with lower IQ or attention-deficit hyperactivity disorder.

OBJECTIVE: Little attention has been paid to the possible protective role of ω-3 polyunsaturated fatty acids (PUFAs) on the visual acuity of school-age children with lower IQs or attention-deficit hyperactivity disorder (ADHD). The aim of this study was to evaluate the effect of dietary ω-3 PUFAs on the visual acuity and red blood cell (RBC) fatty acid compositions of these children. METHODS: We randomly assigned 179 children with lower IQs or ADHD to receive ordinary eggs (control group, n = 90) or eggs rich in C18:3 ω-3, eicosapentaenoic acid (EPA, 20:5 ω-3) and docosahexaenoic acid (DHA, 22:6 ω-3) for 3 mo (study group, n = 89). Before and after the intervention, distance visual acuity was tested using an E chart and the RBC fatty acid composition was determined using capillary gas chromatography. RESULTS: Three months later, 171 children completed the follow-up with the exception of 8 children who were unavailable during follow-up. Both groups of children showed a significant improvement in visual acuity (P < 0.05), however, visual acuity in the study group was significantly better than that of the control group (P = 0.013). The C18:3 ω-3 (P = 0.009), DHA (P = 0.009) and ∑ω-3 (P = 0.022) levels of the intervention group were significantly higher than those of the control group, while the C20:4 ω-6 (P = 0.003), C22:4 ω-6 (P = 0.000), ∑ω-6 (P = 0.001), ∑ω-6/∑ω-3 (P = 0.000) and arachidonic acid/DHA (P = 0.000) of the study group were significantly lower than those of the control group. No significant differences in the levels of C18:2 ω-6 (P = 0.723), C20:2 ω-6 (P = 0.249), C20:3 ω-6 (P = 0.258), C20:5 ω-3 (P = 0.051), or C22:5 (P = 0.200) were found between the two groups. CONCLUSIONS: Dietary supplementation with ω-3 PUFAs improves both visual acuity and the RBC fatty acid profile in school-age children with lower IQs or ADHD.

Position of the Academy of Nutrition and Dietetics: nutrition services for individuals with intellectual and developmental disabilities and special health care needs.

It is the position of the Academy of Nutrition and Dietetics that nutrition services provided by registered dietitian nutritionists (RDNs) and nutrition and dietetics technicians, registered (NDTRs), who work under RDN supervision, are essential components of comprehensive care for adults with intellectual and developmental disabilities (IDD) and children and youth with special health care needs (CYSHCN). Nutrition services should be provided throughout life in a manner that is interdisciplinary, family-centered, community based, and culturally competent. Individuals with IDD and CYSHCN have many risk factors requiring nutrition interventions, including growth alterations (eg, failure to thrive, obesity, or growth retardation), metabolic disorders, poor feeding skills, drug-nutrient interactions, and sometimes partial or total dependence on enteral or parenteral nutrition. Furthermore, these individuals are also more likely to develop comorbid conditions, such as obesity or endocrine disorders that require nutrition interventions. Poor nutrition-related health habits, limited access to services, and long-term use of multiple medications are considered health risk factors. Timely and cost-effective nutrition interventions can promote health maintenance and reduce risk and cost of comorbidities and complications. Public policy for individuals with IDD and CYSHCN has evolved, resulting in a transition from institutional facilities and programs to community and independent living. The expansion of public access to technology and health information on the Internet challenges RDNs and NDTRs to provide accurate scientific information to this rapidly growing and evolving population. RDNs and NDTRs with expertise in this area are best prepared to provide appropriate nutrition information to promote wellness and improve quality of life.

Vitamin D supplementation in children with epilepsy and intellectual disability.

BACKGROUND: Children with epilepsy and intellectual disability have an increased risk of vitamin D deficiency. In this patient group, it is neither clear which factors are associated with the level of 25-hydroxyvitamin D nor what the therapeutic results are when Dutch guidelines are followed. METHODS: This retrospective study included 30 patients who, in October 2012, were residents of the children's wards of a tertiary epilepsy center in The Netherlands (Kempenhaeghe). From November 2012 onward they received cholecalciferol supplementation in doses that met or exceeded Dutch guidelines. At baseline, after 6, and 15 months, serum 25-hydroxyvitamin D concentration was measured. RESULTS: At baseline, the vitamin D status in 11 (36.7%) residents was found to be deficient, in 10 (33.3%) to be insufficient and in 9 (30.0%) sufficient. Supplementation dose, diet, body mass index, intellectual disability, and mobility were significantly associated with baseline 25-hydroxyvitamin D concentrations. The mean 25-hydroxyvitamin D concentration increased significantly from 57.40 ± 22.00 nmol/L at baseline to 89.47 ± 26.77 nmol/L after 15 months (P < 0.001). In spite of supplementation ranging from 400 to 1200 IU/day, 64% of the residents in the deficient category and 30% of those with an insufficient level at baseline failed to attain a sufficient vitamin D status after 15 months. CONCLUSIONS: Not all residents reached a sufficient vitamin D status after supplementation at least equal to the amount recommended by the Dutch guidelines. In a high-risk population, such as our residents, we advise monitoring 25-hydroxyvitamin D concentrations, adjusting supplementation accordingly and following patients to ensure they reach sufficiency.

Training support staff to modify fluids to appropriate safe consistencies for adults with intellectual disabilities and dysphagia: an efficacy study.

BACKGROUND: Modifying the consistency of food and drink is a strategy commonly used in the management of dysphagia for people with intellectual disabilities (ID). People with ID often depend on others for the preparation of food and drink and therefore depend on those caregivers achieving the correct consistency to keep them safe and avoid discomfort during mealtimes. Clinical experience and prior research have demonstrated that although training can improve modification, carers often find modification difficult and potentially stressful and recommend additional support for carers. Fluid consistency is often modified through the addition of powdered thickener. This study investigates the efficacy of typical training and use of consistency guides, the Thickness Indicator Model (TIM) tubes, in helping carers to modify fluids accurately. METHOD: A 3 × 3 pre-post experimental design with a control group was employed to compare the observed accuracy of modification across three groups and at three time points (pre-intervention baseline, immediately post-training intervention and 3-10 months post-training). Sixty-two paid carers who supported people with ID were recruited to participate in the study and each was randomly allocated to one of the three groups: a control group given written guidance only, a group who received typical training and written guidance and a group who received training, written guidance and the TIM tubes. RESULTS & CONCLUSIONS: Typical training resulted in significantly greater carer accuracy in modifying fluid consistencies when compared with written guidance alone. Use of the TIM tubes also significantly improved accuracy in the modification of drinks compared with the group who modified with the aid of written guidance alone. At 3-10-month follow-up only the group who received typical training alongside the TIM tubes were significantly more accurate than the Written Guidance group. Further research is warranted to ascertain the effectiveness of the training and the utility of the TIM tubes in improving accuracy over a longer time scale and in individuals' usual living environments.

Polyunsaturated fatty acid-enriched diet therapy for a child with epilepsy.

The ketogenic diet (KD) is a high-fat, low-carbohydrate diet with an established efficacy for treating medically refractory epilepsy in children. Fatty acids are the most important constituent of the KD in all aspects of efficacy and complications. Among fatty acids, polyunsaturated fatty acids (PUFAs) increase anticonvulsant properties and reduce the complications associated with the high-fat diet. Here, we report a 7-year-old boy with Lennox-Gastaut syndrome combined with mitochondrial respiratory chain complex I deficiency, whose medically intractable seizures have been successfully controlled with a PUFA-enriched modified Atkins diet without any significant adverse events. The diet consists of canola oil and diverse menu items like fish and nuts instead of olive oil and has an ideal 1:2.8 ratio of omega-3 to omega-6. In addition, fractionation of this boy's plasma showed normal levels of fatty acids, including omega-3 (alpha-linoleic acid, eicosapentaenoic acid) and omega-6 (linoleic acid, arachidonic acid) as well as monounsaturated fatty acids (oleic acid). Plasma docosahexanoic acid remained low after PUFA-enriched diet therapy. PUFA-enriched diet therapy is likely to increase the efficacy of diet therapy and reduce complications of a high-fat diet in children with refractory epilepsy.

[Influence of ketogenic diet on the clinical effects and electroencephalogram features in 31 children with pharmacoresistant epileptic encephalopathy].

OBJECTIVE: To investigate the effect of ketogenic diet (KD) on the clinical and electroencephalogram features in children with pharmacoresistant epileptic encephalopathy. METHOD: Thirty-one children (19 boys, 12 girls) aged 7 months to 7 years (mean 2 years 5 month) with epilepsy refractory to conventional antiepileptic drugs (AEDs) were included in this study. In addition to their original AED treatment, the children were assigned to different ketogenic diets based on their age. The prospective electro-clinical assessment was performed prior to the KD and then one week, one month and again 3 months after the initiation of therapy, respectively. RESULT: The reduction of seizure frequency in 52%, 68% and 71% of all patients exceeded 50% one week, one month and three months after KD treatment respectively. KD is particularly effective in myoclonic astatic epilepsy (MAE; Doose Syndrome) and West syndrome with 100% and 81.25% of the patients having a greater than 50% seizure reduction, respectively. After 3 months of KD treatment, more than 2/3 patients experienced a reduction in interictal epileptiform discharges (IEDs) and improvement in EEG background. CONCLUSION: The clinical and electroencephalographic improvement confirms that KD is beneficial in children with refractory epilepsy.

Glycemic index treatment using Japanese foods in a girl with Lennox-Gastaut syndrome.

We introduced a low glycemic index treatment using Japanese ethnic foods to a 13-year-old girl with Lennox-Gastaut syndrome caused by tuberous sclerosis complex. She had previously refused the modified Atkins diet within 2 weeks of diet treatment because of its restrictiveness. The low glycemic index treatment was implemented by limiting the daily carbohydrate intake to 50 g of foods with a glycemic index of less than 50 relative to that of glucose, which included udon, soba, and unpolished Japonica rice with natto. One month after the initiation of the diet therapy, the clusters of tonic seizures for 30 to 60 minutes during sleep were reduced from two or three times per week to once or twice per month, and the frequent myoclonic seizures in the awake state disappeared. She has been on the diet therapy for more than 1 year, and the efficacy of the diet has been sustained. Low glycemic index treatment should be considered for patients with medication-resistant epilepsy who cannot tolerate restrictive diet therapies. Japanese ethnic foods can be used for this diet therapy.

Disturbed energy metabolism and muscular dystrophy caused by pure creatine deficiency are reversible by creatine intake.

Creatine (Cr) plays an important role in muscle energy homeostasis by its participation in the ATP-phosphocreatine phosphoryl exchange reaction mediated by creatine kinase. Given that the consequences of Cr depletion are incompletely understood, we assessed the morphological, metabolic and functional consequences of systemic depletion on skeletal muscle in a mouse model with deficiency of l-arginine:glycine amidinotransferase (AGAT(-/-)), which catalyses the first step of Cr biosynthesis. In vivo magnetic resonance spectroscopy showed a near-complete absence of Cr and phosphocreatine in resting hindlimb muscle of AGAT(-/-) mice. Compared with wild-type, the inorganic phosphate/ß-ATP ratio was increased fourfold, while ATP levels were reduced by nearly half. Activities of proton-pumping respiratory chain enzymes were reduced, whereas F(1)F(0)-ATPase activity and overall mitochondrial content were increased. The Cr-deficient AGAT(-/-) mice had a reduced grip strength and suffered from severe muscle atrophy. Electron microscopy revealed increased amounts of intramyocellular lipid droplets and crystal formation within mitochondria of AGAT(-/-) muscle fibres. Ischaemia resulted in exacerbation of the decrease of pH and increased glycolytic ATP synthesis. Oral Cr administration led to rapid accumulation in skeletal muscle (faster than in brain) and reversed all the muscle abnormalities, revealing that the condition of the AGAT(-/-) mice can be switched between Cr deficient and normal simply by dietary manipulation. Systemic creatine depletion results in mitochondrial dysfunction and intracellular energy deficiency, as well as structural and physiological abnormalities. The consequences of AGAT deficiency are more pronounced than those of muscle-specific creatine kinase deficiency, which suggests a multifaceted involvement of creatine in muscle energy homeostasis in addition to its role in the phosphocreatine-creatine kinase system.

Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy.

Autism spectrum disorders are a genetically heterogeneous constellation of syndromes characterized by impairments in reciprocal social interaction. Available somatic treatments have limited efficacy. We have identified inactivating mutations in the gene BCKDK (Branched Chain Ketoacid Dehydrogenase Kinase) in consanguineous families with autism, epilepsy, and intellectual disability. The encoded protein is responsible for phosphorylation-mediated inactivation of the E1α subunit of branched-chain ketoacid dehydrogenase (BCKDH). Patients with homozygous BCKDK mutations display reductions in BCKDK messenger RNA and protein, E1α phosphorylation, and plasma branched-chain amino acids. Bckdk knockout mice show abnormal brain amino acid profiles and neurobehavioral deficits that respond to dietary supplementation. Thus, autism presenting with intellectual disability and epilepsy caused by BCKDK mutations represents a potentially treatable syndrome.

Efficacy of the ketogenic diet in Lennox-Gastaut syndrome: a retrospective review of one institution's experience and summary of the literature.

AIM: To determine the efficacy of the ketogenic diet for children with Lennox-Gastaut syndrome (LGS) at our institution and in the literature. METHOD: The records of children with LGS initiated on the ketogenic diet at our institution from 1994 to 2010 were reviewed. Inclusion criteria included the presence of ≤2.5Hz spike-and-wave complexes on electroencephalogram, multiple seizure types including tonic, atonic, or atypical absence, developmental delay, and age under 1 year. We additionally reviewed the literature for cases of LGS treated with the ketogenic diet and their outcomes. RESULTS: Seventy-one children (41 males, 30 females, median age 3y 6mo, range 18mo-18y), with LGS were initiated on the ketogenic diet. Using an intent-to-treat analysis, after 6 months, 36 (51%) achieved more than 50% seizure reduction, 16 (23%) experienced more than 90% seizure reduction, and 1 (1%) achieved seizure freedom. Results were similar after 12 months. Age, sex, side effects, valproate use, and history of infantile spasms were not predictive of more than 90% seizure reduction. In the literature, 88 of 189 (47%) children with LGS had more than 50% seizure reduction after 3 to 36 months of ketogenic diet treatment. INTERPRETATION: The ketogenic diet is efficacious in the treatment of LGS, with approximately one-half of children responding at 12 months.

Physical activity and nutrition health promotion interventions: what is working for people with intellectual disabilities?

A scoping review of studies on physical activity and nutrition health promotion interventions for individuals with intellectual disabilities was conducted. Searches included MEDLINE, PsycINFO, and CINAHL databases from 1986 through July 2006. The final number included 11 articles comprising 12 studies. Generally, this review indicated some evidence for fitness and psychosocial benefits of community-based physical activity and exercise programs for adults with intellectual disabilities. When combined with a more comprehensive health behavior education program incorporating exercise and nutrition information, some evidence exists for reductions in weight.

Adults with late diagnosed PKU and severe challenging behaviour: a randomised placebo-controlled trial of a phenylalanine-restricted diet.

BACKGROUND: Although early diagnosis and treatment in phenylketonuria (PKU) leads to excellent outcomes, a population of adults born before the introduction of newborn screening exists. They can have severe intellectual disabilities and behavioural problems, and are often dependent on full-time carers. Anecdotal evidence suggests that a diet that lowers blood phenylalanine concentration can have significant benefits upon behaviour. METHODS: A prospective double-blind randomised placebo-controlled crossover trial of phenylalanine-restricted diet was performed in a group of 34 adults (aged 21-61 years, median 49) with late diagnosed PKU with severe challenging behaviour. RESULTS: Only 17 completed the 60 week study: seven withdrew before the end of the baseline period; five withdrew during the first diet period; five withdrew during the second diet period (after moving into placebo phase). The mean (SD) blood phenylalanine was 1570 (222) micromol/l during baseline, 553(158) mumol/l during the active phase and 1444 (255) micromol/l during the placebo phase. In the 22 participants exposed to both active and placebo phases, no differences were demonstrated in behaviour assessed by the Aberrant Behavior Checklist and Vineland Adaptive Behavior Scales, behaviour diaries or on video analysis of direct observations. However, 76% of carers' comments were scored as positive during the active phase, compared with 54% during the placebo phase (chi(2) = 38.06, p<0.001). CONCLUSIONS: There are significant challenges in studying people with intellectual disabilities and considerable difficulties in instituting phenylalanine-restricted diet in this population. However, if attempted, there are potential benefits to quality of life for the individuals with PKU and their carers.

Adults with untreated phenylketonuria: out of sight, out of mind.

Some people with phenylketonuria who were born before screening began were never treated and are still alive. Here we report that far fewer people with untreated phenylketonuria were detected than are thought to exist (about 2000). The majority of those traced had high support needs, challenging behaviour and other symptoms of phenylketonuria. No significant differences were found between those who had or had not tried the phenylalanine-restricted diet. A randomised controlled trial is required to examine the effect of trying the low-phenylalanine diet for people with untreated phenylketonuria.