End-of-Life Care Patterns Associated with Pediatric Palliative Care among Children Who Underwent Hematopoietic Stem Cell Transplant.

Stem cell transplantation (SCT) is an intensive therapy offering the possibility of cure for life-threatening conditions but with risk of serious complications and death. Outcomes associated with pediatric palliative care (PPC) for children who undergo SCT are unknown. Therefore, we evaluated whether PPC consultation is associated with differences in end-of-life (EOL) care patterns for children who underwent SCT and did not survive. Medical records of children who underwent SCT at Boston Children's Hospital/Dana-Farber Cancer Institute for any indication from September 2004 to December 2012 and did not survive were reviewed. Child demographic and clinical characteristics and PPC consultation and EOL care patterns were abstracted. Children who received PPC (PPC group) were compared with those who did not (non-PPC group). Children who received PPC consultation (n = 37) did not differ from the non-PPC group (n = 110) with respect to demographic or clinical characteristics, except they were more likely to have undergone unrelated allogeneic SCT (PPC, 68%; non-PPC, 39%; P = .02) or to have died from treatment-related toxicity (PPC, 76%; non-PPC, 54%; P = .03). PPC consultation occurred at a median of .7 months (interquartile range [IQR], .4 to 4.2) before death. PPC consultations most commonly addressed goals of care/decision-making (92%), psychosocial support (84%), pain management (65%), and non-pain symptom management (70%). Prognosis discussions (ie, the likelihood of survival) occurred more commonly in the PPC group (PPC, 97%; non-PPC, 83%; P = .04), as did resuscitation status discussions (PPC, 88%; non-PPC, 58%; P = .002). These discussions also occurred earlier in the PPC group, for prognosis a median of 8 days (IQR, 4 to 26) before death compared with 2 days (IQR, 1 to 13) in the non-PPC group and for resuscitation status a median of 7 days (IQR, 3 to 18) compared with 2 days (IQR, 1 to 5) in the non-PPC group (P < .001 for both of the timing of prognosis and resuscitation status discussions). The PPC group was also was more likely to have resuscitation status documented (PPC, 97%; non-PPC, 68%; P = .002). With respect to patterns of care, compared with non-PPC, the PPC group was as likely to die in a medicalized setting (ie, the hospital) (PPC, 84%; non-PPC, 77%; P = .06) or have hospice care (PPC, 22%; non-PPC, 18%; P = .6). However, among children who died in the hospital, those who received PPC were more likely to die outside the intensive care unit (PPC, 80%; non-PPC, 58%; P = .03). In addition, the PPC group was less likely to receive intervention-focused care such as intubation in the 24 hours before death (PPC, 42%; non-PPC, 66%; P = .02) or cardiopulmonary resuscitation (PPC, 3%; non-PPC, 20%; P = .03) at EOL. Children who received PPC for at least a month were more likely to receive hospice care (PPC, 41%; non-PPC, 5%; P = .01). Children who underwent SCT and did not survive were likely to die in a medicalized setting, irrespective of PPC. However, PPC was associated with less intervention-focused care and greater opportunity for EOL communication and advance preparation. In the intense, cure-oriented SCT setting, PPC may facilitate advance care planning in this high-risk population.

Increased Cardiovascular Risk in Psoriatic Arthritis: Results From a Case-Control Monocentric Study.

Background: Psoriatic arthritis (PsA) is associated with increased cardiovascular morbidity and mortality. The aims of our real-life study were to compare the prevalence of cardiovascular risk factors (CVRFs) and cardiovascular events (CVEs) among patients with PsA with a control population, to evaluate the impact of correcting factors in equations that assess cardiovascular risk (CVR) in PsA, and to determine the percentage of patients who reach the LDLc target as indicated by the European guidelines. Methods: In this observational cross-sectional monocentric case-control study, we used a standardized procedure to systematically assess patients with PsA aged 25-85 years who met the Classification for Psoriatic Arthritis (CASPAR) criteria. Controls were extracted from the MOnitoring NAtionaL du rISque Artériel (MONALISA) study. We compared the prevalence of CVRFs, CVEs, the CVR, and the percentage of patients reaching recommended LDLc target in both populations. The CVR was first assessed using SCORE and QRISK2 equations. Then, the SCORE equation was corrected by applying a 1.5 multiplication factor, as recommended by EULAR for rheumatoid arthritis (SCORE-PsA), and the QRISK2 was corrected using the "rheumatoid arthritis" item (QRISK2-PsA). Results: A total of 207 PsA and 414 controls were included. CVRFs and CVEs were more frequent in the PsA group. After controlling for age and gender, atherothrombotic disease was increased in the PsA population (SCORE p = 0.002, QRISK2 p = 0.001). Using the SCORE-PsA increased the percentage of patients with a high or very high CVR from 39.3 to 45.3% in the PsA group. Similarly, using the QRISK2-PsA increased the percentage of patients with a CVR ≥ 10% from 44.9 to 53.2%. The percentages of patients with PsA with high LDLc in the high and very high CVR groups were not significantly different from controls, despite a trend in favor of patients with PsA. Of the 83 PsA with a QRISK2 ≥ 10%, only 22.9% were treated with statin vs. 35.8% of the 134 controls. The QRISK2-PsA score did not alter these results. Conclusion: In real-life, patients with PsA have a higher prevalence of CVRFs, as well as a higher prevalence of CVEs compared to the general population. The CVR is higher in the PsA population than in the controls either using the SCORE and QRISK2 equations or using the corrected SCORE- PsA and QRISK2-PsA equations.

Psychosocial issues and outcomes in maternal PKU.

Elevated phenylalanine (Phe) levels in pregnant women with PKU are teratogenic. Fetal damage due to elevated maternal Phe levels during pregnancy is known as maternal phenylketonuria (MPKU). The risk of birth defects in MPKU, including global developmental delays, microcephaly, congenital heart disease, and low birth weight, can be dramatically reduced by controlling Phe levels during pregnancy (metabolic control). Phe levels should be maintained in the range of 120-360 micromol/L, ideally starting before pregnancy begins (i.e., when planning a pregnancy). If control is not achieved before pregnancy (e.g., if the pregnancy was unplanned), good outcomes are still possible if metabolic control is established by 8 weeks of pregnancy. Unfortunately, metabolic control before and during pregnancy can be poor. As well, many mothers stop treatment after pregnancy, which can decrease the mother's ability to focus on her child and increase her risk of behavioral and psychological problems. This can have a negative effect on the home environment. Many factors affect adherence to the strict diet used to control Phe levels, including poor access to medical care, lack of reimbursement for medical foods (in some regions, such as parts of the United States), practical difficulties with implementing the diet, financial constraints, demographics, and psychosocial issues. A comprehensive treatment approach that begins prior to pregnancy and continues after the infant is born may help to improve the management of MPKU. This approach should include education of girls about MPKU at an early age, interventions to prevent unplanned pregnancies, psychosocial support, improved treatment access and reimbursement for medical foods, and treatment guidelines. Treatments such as sapropterin may also have a role in improving metabolic control during pregnancy.

Cutaneous gamma/delta T-cell lymphoma.

Only 40 cases of primary cutaneous gamma/delta T-cell lymphoma (GD-TCL) have been described. GD-TCL was included as a provisional entity in the WHO-EORTC classification of cutaneous lymphomas in 2005. GD-TCL often failed to respond to polychemotherapy and radiation therapy and have a poor prognosis with a mean survival of only 15 months. We present a patient treated with surgery, immunomodulatory therapy, and polychemotherapy. He then received hematopoietic stem cell transplantation and has been in complete remission since. Allogeneic stem cell transplantation appears to be a promising therapeutic option for aggressive and generally fatal lymphomas like GD-TCL.

Distraction as a simple and effective method to reduce pain during local anesthesia: A randomized controlled trial.

BACKGROUND: The administration of local anesthetics is considered the most unpleasant part of office-based surgery. Many procedural and pharmacological strategies have been developed to minimize pain. In children and adolescents, distraction has been demonstrated to be an effective way of minimizing pain during local anesthesia. We present a randomized controlled trial of the effect of distraction on pain during local anesthesia in adults. MATERIAL AND METHODS: We have included 115 patients undergoing small office-based surgery to either the face, wrist, or hand. We randomized these patients between two groups: a control group and an intervention group. The intervention group watched a distractive video during the administration of the local anesthetic; for the rest the surgical procedures were performed in an equal fashion in both groups. Preoperative anxiety was scored from 0 to 10 and pain experienced during the injection of local anesthetic was measured on the visual analogue scale of pain (VAS), ranging from 0 to 10. Patient satisfaction was measured on the Patient Satisfaction Questionnaire (PSQ-18), ranging from 18 to 90. RESULTS: Patients had an equal anticipated pain score in control and intervention group. In the intervention group, a reduction of pain scores of 1 point was observed (p = 0.01). There was no difference in patient satisfaction scores between both groups. DISCUSSION: In this study, we demonstrate the pain minimizing effect of distraction during the administration of local anesthesia. Less experienced pain did not result in improved patient satisfaction in our study. We encourage physicians to seek ways to actively distract patients during unpleasant procedures.

Mutations in the regulatory domain of phenylalanine hydroxylase and response to tetrahydrobiopterin.

Tetrahydrobiopterin (BH4) is a co-factor that enhances the activity of other enzymes, and this co-factor level is found to be affected in phenylketonuria (PKU), an amino acid metabolism disorder. The present study was aimed at understanding the effect of BH4 on mutations in the regulatory domain of phenylalanine hydroxylase (PAH). Among 14 patients, 5 patients were classical PKU, 3 were atypical PKU, and 6 were mild PKU. All of these patients had at least one mutation in the regulatory domain. Patients were given 10 mg/kg BH4, and the response of blood phenylalanine (Phe) levels was monitored following treatment. The level of blood Phe decreased after BH4 treatment in all of the patients. These studies suggest that mutations in the regulatory domain also responded to BH4 even if the patient had classical PKU.

Neuropathology of a 4-month-old infant born to a woman with phenylketonuria.

We evaluated the brain of a 4-month-old male infant whose mother had inadequately controlled maternal phenylketonuria (MPKU). At autopsy his brain was normally developed but underweight. We found ventriculomegaly, hypoplastic cerebral white matter, and delay of myelination in late myelinating tracts without white matter astrocytosis and without chronic lesions in any gray matter structure. We compared the development of the infant's white matter tracts with published data on infant myelination. Congenital heart disease complicated the case. Abnormalities in developmental white matter may account for neurological abnormalities in infants with MPKU.

Regional and phenotype heterogeneity of cellular prion proteins in the human brain.

Transmissible spongiform encephalopathies (TSEs) are neurological disorders that include genetic, infectious and sporadic forms of human Creutzfeldt-Jakob disease (CJD). The pathogenic agent is the prion protein that is composed of an abnormal isoform (PrP(Sc)) of a host-encoded protein (PrP(C)). Analysis of the relative amounts of PrP(Sc) glycoforms has been used to discriminate between various agents involved in TSE. The distribution and efficiency of conversion to PrP(Sc) can be influenced by differences in the expression of PrP(C). However, little attention has been given so far to the banding patterns of PrP(C). Using four different antibodies recognizing amino- and carboxyl-terminal PrP sequences we analysed the glycoforms of PrP(C) in seven regions of the human brain using brains obtained from six subjects. For determination of the staining intensities, signals were quantified by densitometry and reproducible patterns were accomplished by many repeated immunoblot analyses. When amino-terminal binding antibodies were used for detection, PrP(C) in the frontal neocortex, nucleus lentiformis, thalamus, hippocampus and cerebellum displayed a glycotype with high staining of the diglycosylated isoforms. This was different from patterns in the pons and medulla oblongata, which showed a high intensity of the nonglycosylated isoform, and PrP(C) proteins, approximately 27 kDa in size, exhibited high staining using the carboxyl-terminal binding antibodies. This intense staining followed from an overlay of full-length and truncated PrP(C) isoforms. Furthermore, we found marked differences in the expression of PrP(C). Variations in the processing of PrP(C) may lead to interregional differences in the glycoform composition of PrP(Sc) in human brains.

Mutations in the phenylalanine hydroxylase gene identified in 95 patients with phenylketonuria using novel systems of mutation scanning and specific genotyping based upon thermal melt profiles.

Phenylketonuria (PKU, MIM 261600; EC 1.14.16.1) results from mutations in the phenylalanine hydroxylase (PAH) gene. Newborn metabolic disease screening uses blood dried on filter paper (DBS) to prospectively identify candidate newborns affected with PKU via an elevated concentration of phenylalanine. However, it is then important to confirm the specific category of PKU since classical PKU requires a stringent diet while milder categories may not require diet and a very important BH4-responsive category may be treated with the PAH cofactor 6R-tetrahydrobiopterin (BH4). Since there is a close genotype-phenotype correlation in PKU, determining the PAH genotype can be extremely important for therapy as well as prognosis. A simple and rapid method of accurately determining the PAH genotype would be a valuable addition to the diagnosis of PKU. Described herein is a means to identify variants in the PAH gene using high-resolution melt profiling, which compares the thermal denaturation profile of a patient sample to that of a control. Regions where the patient and control samples produce a common profile were not further evaluated, while those regions where the patient profile deviates from the control were assessed by DNA sequencing. Additionally described is a scheme utilizing redundant analysis with melt profile controls and a novel multiplex genotyping assay to triage deviation owing to known polymorphisms. Two mutations were identified in 93 of the 95 patients assessed and in the remaining two patients a single mutation was identified. Melt profiling provided 99% sensitivity to identify sequence variants in the PAH gene.

Tetrahydrobiopterin and maternal PKU.

A 29-year-old woman with PKU is presented, who was successfully treated with phenylalanine restriction as well as oral BH4 during this pregnancy, with a normal outcome. Her PAH mutation was R408W/F39L. Remarkably, the blood phenylalanine control was easily accomplished during this pregnancy. The lack of nausea and vomiting during the first trimester suggests that the occurrence of CHD in babies born to women with PKU may be reduced with BH4.

Inter-individual variation in brain phenylalanine concentration in patients with PKU is not caused by genetic variation in the 4F2hc/LAT1 complex.

It remains a question why some patients with phenylketonuria (PKU) have high IQ and low brain phenylalanine (Phe) concentrations in spite of high blood Phe levels. One possible explanation for the low brain Phe concentrations in these patients would be a reduced transport of Phe across the blood-brain barrier. The 4F2hc/LAT1 complex has been suggested to be the most important molecular component responsible for this transport. To test the hypothesis that structural variant(s) in the genes encoding 4F2hc and LAT1 might result in a complex with reduced affinity for Phe, we have screened the two genes for sequence variants in a group of 13 PKU patients with a low ratio of brain to blood Phe concentrations. Several common sequence variants were identified, but none of these is predicted to affect the resulting protein product. Our data suggest that individual vulnerability to Phe in patients with PKU is not due to structural variants in the 4F2hc/LAT1 complex.

Response of patients with phenylketonuria in the US to tetrahydrobiopterin.

Tetrahydrobiopterin (BH4) responsive forms of phenylketonuria (PKU) have been recognized since 1999. Subsequent studies have shown that patients with PKU, especially those with mild mutations, respond with lower blood phenylalanine (Phe) concentrations following oral administration of 6-R-L-erythro-5,6,7,8-tetrahydrobiopterin (BH4). To determine the incidence of BH4 responding PKU patients in the United States and characterize their phenylalanine hydroxylase (PAH) mutations, a study was undertaken at UTMB in Galveston and the Children's Hospital of Los Angeles on 38 patients with PKU. Patients were screened by a single oral dose of BH4, 10 mg/kg and blood Phe and tyrosine were determined at 0, 4, 8, and 24 h. Twenty-two individuals (58%) responded with marked decrease in blood Phe (>30%) at 24h. Some of the patients that responded favourably were clinically described as having Classical PKU. Blood tyrosine concentrations did not change significantly. Twenty subjects with PKU, responsive and non-responsive to BH4, were enrolled in a second study to evaluate blood Phe response to ascending single doses of BH4 with 10, 20, and 40 mg/kg and to evaluate multiple daily doses, for 7 days each, with 10 and 20 mg/kg BH4. The 7-day trial showed a sustained decrease in blood Phe in 14 of 20 patients taking 20 mg/kg BH4 (70%). Of these 14 patients, 10 (71%) responded with a significant decrease in blood Phe following 10 mg/kg BH4 daily. To understand the mechanism of response to BH4, the kinetics and stability of mutant PAH were studied. We found that mutant PAH responds with increase in the residual enzyme activity following BH4 administration. The increase in activity is multi-factorial caused by increased stability, chaperone effect, and correction of the mutant Km. These studies indicate that BH4 can be of help to patients with PKU, including some considered to have Classical PKU. The PKU population in US is heterogeneous and mutations can be varied so mutations need to be characterized and response to BH4 tested. It is more likely that mutations with residual activity should respond to BH4, therefore the clinical definition of "Classical PKU" should be reconciled with the residual activity of PAH mutations.

Mental illness in mild PKU responds to biopterin.

A 25-year-old woman with mild hyperphenylalaninemia developed disabling depression and panic attacks. The mutations on the phenylalanine hydroxylase gene indicated that she might be responsive to tetrahydrobiopterin therapy. Mutation analyses were performed by the John F. Kennedy Institute in Glostrup, Denmark. The response to tetrahydrobiopterin therapy was impressive at an oral dose of 50 mg twice a day. A 25-year-old woman with mild hyperphenylalaninemia due to a PAH mutation of IVS12nt1g-->a/E390G has been treated for 1 year with BH4 therapy. A maintenance dosage of only 100 mg/day has resulted in significant improvement of depression and panic attacks, with discontinuation of psychotropic medication.

Large neutral amino acid therapy and phenylketonuria: a promising approach to treatment.

Six subjects with classical phenylketonuria (PKU) were treated with large neutral amino acid supplements (PreKUnil, Nilab, Dk) at 0.4g/kg/day in equally divided doses three times each day on an increased natural protein diet. All six subjects had low or deficient blood concentrations of both tyrosine and tryptophan, which are precursors for dopamine and serotonin, respectively, at the beginning of the study and were increased substantially throughout the study. Blood phenylalanine concentrations remained essentially unchanged, while the brain phenylalanine concentrations gradually decreased toward the carrier range as seen in parents of children with PKU. Two subjects were diagnosed with clinical depression and were in counseling programs at initiation of the study. At the end of the study all patients reported increased energy and overall improvement in well-being.

Progressive neurologic disability in methylmalonic acidemia despite transplantation of the liver.

UNLABELLED: Methylmalonic acidemia unresponsive to cobalamin is often fatal in infancy. Patients have been considered candidates for hepatic transplantation and experience has been that the procedure eliminates the life-threatening episodes of ketoacidosis that characterize this disease. CONCLUSION: experience with a 24-year-old patient treated with hepatic transplantation indicates that this procedure does not prevent progressive renal failure and neurologic dysfunction.

Brain phenylalanine concentrations in phenylketonuria: research and treatment of adults.

OBJECTIVE: To assess the effects of 2 pharmacologic interventions (amino acid supplements) on the brain levels of phenylalanine (Phe) in adults with phenylketonuria (PKU). METHODS: A prospective study was conducted in an outpatient treatment and follow-up setting. The volunteers who were recruited for the first intervention included 4 subjects with classic PKU. The second intervention included 3 adults with classic PKU. The first intervention consisted of dietary supplementation during 1 day with Phlexy 10. Two individuals were given a dose of 0.5 g/kg/d, and 2 were given 1.0 g/kg/d. The second intervention consisted of dietary supplementation with PreKUnil at 0.4 g kg/d over a period of 6 months. Brain Phe was measured by magnetic resonance spectroscopy. The number of the patients involved precluded analysis for significance. RESULTS: The first, shorter intervention resulted in a decrease in brain Phe. The second intervention resulted in a 20% decrease in brain Phe, which was maintained after 6 months of treatment. CONCLUSION: Dietary supplementation of large neutral amino acids seems to lower the brain Phe in adults who have PKU and have difficulty following their diet.

Research design, organization, and sample characteristics of the Maternal PKU Collaborative Study.

OBJECTIVE: The Maternal PKU Collaborative Study (MPKUCS) was initiated in 1984 by the National Institute of Child Health and Human Development (NICHD). The purpose was to assess the efficacy of dietary restriction of phenylalanine in reducing morbidity in offspring of women with hyperphenylalaninemia (HPA). A contract was awarded to Childrens Hospital Los Angeles as the Coordinating Center to provide implementation of the research protocol, data collection, and analysis. METHODS: The Study included four regional contributing centers: Childrens Hospital Los Angeles (Western Region), Boston Children's Hospital (Northeast Region), University of Illinois (Midwest Region), and University of Texas Medical Branch, Galveston (Southeast Region). Within each region, many participating clinics were responsible for obstetric care, treatment, and monitoring protocols. In 1985, Canada joined the MPKUCS, and in 1992, Germany entered. They were selected because they provided dietary supplies and strong professional services. Acquisition began in 1984 and ended in October 1995. The study included 574 pregnancies in women with HPA and 100 control subjects matched on age, race, parity, and weeks of gestation. The sample included women with blood phenylalanine values >240 micromol/L, 66% of whom had classical PKU, 22% had atypical PKU, and 12% had mild HPA. Informed consents were obtained on all participants. The women ranged in age from 15 to 36 years of age, with a mean age at conception of 23 years. Teenage pregnancies accounted for 19%. Seventy-five percent graduated from high school. Offspring included 416 newborns, 317 of whom were evaluated at 4 years of age and 289 at 6 to 7 years. Follow-up involved medical, nutritional, psychosocial, and psychological assessments. CONCLUSION: Women with PKU treated before conception and in control of their blood phenylalanine levels between 120 and 360 micromol/L (2-6 mg) exhibited normal pregnancies and neonatal outcome. Surprisingly, women who achieved control in the recommended range by 8 weeks of pregnancy also had a normal fetal outcome.

Correction of kinetic and stability defects by tetrahydrobiopterin in phenylketonuria patients with certain phenylalanine hydroxylase mutations.

Phenylketonuria patients harboring a subset of phenylalanine hydroxylase (PAH) mutations have recently shown normalization of blood phenylalanine levels upon oral administration of the PAH cofactor tetrahydrobiopterin [(6R)-L-erythro-5,6,7,8-tetrahydrobiopterin (BH4)]. Several hypotheses have been put forward to explain BH4 responsiveness, but the molecular basis for the corrective effect(s) of BH4 has not been understood. We have investigated the biochemical, kinetic, and structural changes associated with BH4-responsive mutations (F39L, I65T, R68S, H170D, E178G, V190A, R261Q, A300S, L308F, A313T, A373T, V388M, E390G, P407S, and Y414C). The biochemical and kinetic characterization of the 15 mutants studied points toward a multifactorial basis for the BH4 responsiveness; the mutants show residual activity (>30% of WT) and display various kinetic defects, including increased Km (BH4) and reduced cooperativity of substrate binding, but no decoupling of cofactor (BH4) oxidation. For some, BH4 seems to function through stabilization and protection of the enzyme from inactivation and proteolytic degradation. In the crystal structures of a phenylketonuria mutant, A313T, minor changes were seen when compared with the WT PAH structures, consistent with the mild effects the mutant has upon activity of the enzyme both in vitro and in vivo. Truncations made in the A313T mutant PAH form revealed that the N and C termini of the enzyme influence active site binding. Of fundamental importance is the observation that BH4 appears to increase Phe catabolism if at least one of the two heterozygous mutations has any residual activity remaining.

Biopterin responsive phenylalanine hydroxylase deficiency.

PURPOSE: Phenylketonuria (PKU) is an autosomal recessive disorder caused by mutations in the phenylalanine hydroxylase (PAH) gene. There have been more than 400 mutations identified in the PAH gene leading to variable degrees of deficiency in PAH activity, and consequently a wide spectrum of clinical severity. A pilot study was undertaken to examine the response to 6-R-l-erythro-5,6,7,8-tetrahydrobiopterin (BH4) in patients with atypical and classical PKU. METHODS: PAH gene mutation analysis was performed using denaturing gradient gel electrophoresis and gene sequencing. Patients with classical, atypical, or mild PKU were orally given BH4 10 mg/kg. Blood phenylalanine and tyrosine levels were determined using tandem MS/MS at 0 hours, 4 hours, 8 hours, and 24 hours intervals. RESULTS: Thirty-six patients were given a single oral dose of 10 mg/kg of BH4. Twenty one patients (58.33%) responded with a decrease in blood phenylalanine level. Of the patients that responded, 12 were classical, 7 atypical, and 2 mild. The mean decline in blood phenylalanine at 24 hours was > 30% of baseline. There were 15 patients who did not respond to the BH4 challenge, 14 of those had classical and one had atypical PKU. Mapping the mutations that responded to BH4 on the PAH enzyme showed that mutations were in the catalytic, regulatory, oligomerization, and BH4 binding domains. Five patients responding to BH4 had mutations not previously identified. CONCLUSION: The data presented suggest higher than anticipated number of PKU mutations respond to BH4, and such mutations are on all the domains of PAH.