Guide for diagnosis and treatment of hyperphenylalaninemia.

IMPORTANCE: Sapropterin hydrochloride, a natural coenzyme (6R-tetrahydrobiopterin) of phenylalanine hydroxylase, was first approved as a treatment for tetrahydrobiopterin deficiency in 1992 in Japan, and was then approved as a treatment for a tetrahydrobiopterin-responsive hyperphenylalaninemia in 2007 and 2008, in the USA and Japan, respectively. Guidelines are required on the proper use of sapropterin hydrochloride for tetrahydrobiopterin-responsive hyperphenylalaninemia. OBSERVATIONS: It is recommended that tetrahydrobiopterin-responsive hyperphenylalaninemia should be diagnosed in all cases of hyperphenylalaninemia, including phenylketonuria, by tetrahydrobiopterin administration tests rather than by phenotype or blood phenylalanine levels. CONCLUSIONS AND RELEVANCE: If tetrahydrobiopterin-responsive hyperphenylalaninemia is diagnosed, all ages can be treated with sapropterin hydrochloride. Although there are reports that sapropterin hydrochloride is effective and safe for the prevention of maternal phenylketonuria, further investigation is required.

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.

[Maternal phenylketonuria]. / Maternális phenylketonuria.

Elevated maternal phenylalanine levels during pregnancy are teratogenic, and may result in embryo-foetopathy, which could lead to stillbirth, significant psychomotor handicaps and birth defects. This foetal damage is known as maternal phenylketonuria. Women of childbearing age with all forms of phenylketonuria, including mild variants such as hyperphenylalaninaemia, should receive detailed counselling regarding their risks for adverse foetal effects, optimally before contemplating pregnancy. The most assured way to prevent maternal phenylketonuria is to maintain the maternal phenylalanine levels within the optimal range already before conception and throughout the whole pregnancy. Authors review the comprehensive programme for prevention of maternal phenylketonuria at the Metabolic Center of Budapest, they survey the practical approach of the continuous maternal metabolic control and delineate the outcome of pregnancies of mothers with phenylketonuria from the introduction of newborn screening until most recently.

Síndrome de fenilquetonuria materna, un nuevo desafío para Chile / Maternal phenylketonuria syndrome, a new challenge for Chile

Phenylquetonuria (PKU) is a hereditary disease, caused by the deficiency or absence of the enzyme phenylalanine hydroxylase, which produces an abnormal conversion of phenylalanine (Phe) to tyrosine. If PKU is not diagnosed and treated during the neonatal period, blood accumulation of Phe causes neurological damage. Chile has a neonatal screening program for PKU and congenital hypothyroidism since 1992; this program has diagnosed 162 PKU patients in Chile, which are being followed-up in INTA, Universidad de Chile. Nowadays, there are 20 PKU patients in adolescence, so we face a new challenge such as maternal PKU syndrome. This syndrome refers to the teratogenic effect of Phe in a pregnant PKU female. The most frequent anomalies are intrauterine growth retardation, microcephaly, global development retardation and congenital heart defects. Their occurrence is directly related to maternal Phe during pregnancy. In order to assure a normal pregnancy and to prevent this syndrome, levels of Phe in blood should be kept between 2 and 6 mgldl prior to conception and throughout pregnancy. Considering this challenge, INTA has proposed a strict protocol of follow-up to improve the compliance to nutritional therapy and prevent maternal PKU syndrome.

La fenilquetonuria (PKU) es una patología hereditaria, producida por la deficiencia o ausencia de la enzima fenilalanina hidroxilasa, lo que impide la metabolización normal de la fenilalanina (FA) a tirosina. La acumulación de fenilalanina en la sangre ocasiona daño neurológico si no es diagnosticada y tratada desde el periodo neonatal. Desde 1992 Chile tiene un programa de pesquisa neonatal de PKU e hipotiroidismo congénito, lo que ha permitido diagnosticar 162 casos con PKU, los que mantienen un seguimiento integral en el INTA, de la Universidad de Chile. Actualmente hay 20 PKU en etapa de adolescencia, por lo que nos enfrentamos a un nuevo desafío, el síndrome de PKU materna. Este síndrome se refiere al efecto teratogénico de la FA en una embarazada con PKU. Las alteraciones más características son el retraso del crecimiento intrauterino, la microcefalia, el retraso global del desarrollo y los defectos cardiacos congénitos. La presencia de estas alteraciones está directamente relacionada con los niveles de FA de la madre durante el embarazo. Para asegurar un embarazo normal y prevenir este síndrome se recomienda la mantención de niveles de FA entre 2 y 6 mg/dl, desde el período preconcepcional y durante todo el embarazo. El INTA considerando este desafío, ha propuesto un protocolo de seguimiento estricto preconcepcional y durante el embarazo con el objetivo de favorecer la adherencia al tratamiento nutricional y prevenir el síndrome de PKU materna.

Maternal phenylketonuria syndrome and case management implications.

Well-established dietary protocols have prevented mental retardation for infants born with phenylketonuria (PKU). Dietary protocols for managing females with PKU in their reproductive years exist but are not followed by most of them. Infants who are born to mothers with PKU who are not on dietary treatment usually have serious medical problems, such as mental retardation, heart defects, and other serious congenital anomalies (e.g., orofacial clefting and bladder exstrophy)--a condition known as maternal PKU syndrome. The focus of this article is to review the pathophysiology, associated developmental issues, and existing management protocols used to manage these two separate but highly connected disorders.

Síndrome de fenilcetonuria materna / Maternal phenylketonuria syndrome

El síndrome de fenilcetonuria materna es una embriopatía que ocurre en hijos de madres fenilalaninémicas que no han recibido tratamiento dietético adecuado preconcepcional ni durante la gestación. El presente articulo expone la semiología, fisiopatología de este síndrome y posibles mecanismos del daño intraútero que provoca. Define las mujeres en riesgo y explica la conducta a seguir con ellas para prevenir la ocurrencia de embriopatía por fenilcetonuria materna en la descendencia. Se enfatiza en el estricto control metabólico desde que la futura madre planifica su gestación y durante todo el embarazo como única opción terapéutica eficaz. Se reafirma el papel protagónico de la atención primaria de salud en la prevención de la embriopatía por fenilcetonuria materna. Las fenilcetonúricas que arriban a la edad reproductiva deben ser clasificadas de riesgo preconcepcional y recibir una amplia información que les permita reconocer las probabilidades que tiene de desarrollar una embriopatía, planificar adecuadamente su embarazo y asumir la necesidad de llevar una dieta restrictiva. Se deben buscar activamente las hiperfenilalaninémicas benignas para que previa dispensarización reciban seguimiento bioquímico y del neurodesarrollo, con énfasis en las hembras que alcanzan la edad reproductiva(AU)

[Phenylketonuria: a children's disease in adulthood]. / Een kinderziekte op de volwassen leeftijd: fenylketonurie.

The prognosis for patients with phenylketonuria (PKU) has improved greatly with early institution of treatment after birth. It was assumed that the diet could be terminated after adolescence but there are strong indications that hyperphenylalaninaemia can have detrimental effects in adult patients. Hyperphenylalaninaemia can cause reversible white matter abnormalities, and is also associated with psychiatric illness, which improves with lowering of the plasma phenylalanine level. Even optimally treated patients generally have a decreased performance with neuropsychological tests compared with subjects without PKU. Elevation of the plasma phenylalanine level leads to worsening of neuropsychological performance, lowering of the level leads to improved performance. Strict metabolic control is necessary during pregnancy in women with PKU in view of the increasing frequency of congenital abnormalities with increasing phenylalanine level. The complexity and demanding nature of the diet treatment make specialised facilities for optimal medical and paramedical care mandatory.

Necessity of complete intake of phenylalanine-free amino acid mixture for metabolic control of phenylketonuria.

The importance of complete or almost complete intake of the recommended amount of phenylalanine-free amino acid mixture (AAM) for control of blood phenylalanine level in patients being treated for phenylketonuria (PKU) has not been universally appreciated. We observed the effect of complete intake of AAM on plasma phenylalanine levels during hospitalization in 6 patients with PKU (5 pregnant women with PKU and 1 child) who had poor metabolic control because of less than full compliance with prescribed AAM intake. Before hospitalization, all but 1 of the patients had blood phenylalanine levels above 1,000 mumol/L; in 1 patient the blood phenylalanine level was 703 mumol/L. During 9 periods of observation in the 6 patients, the levels of plasma phenylalanine decreased to the recommended range of below 360 mumol/L within 2 to 6 days of hospitalization. These experiences indicate a close relationship between compliance with prescribed AAM intake and control of blood phenylalanine level. We propose that hospitalization be considered when patients with PKU who are consuming a phenylalanine-restricted diet fail to maintain blood phenylalanine levels in the targeted range despite reported compliance with the prescribed intake of dietary phenylalanine and AAM.

The Resource Mothers Program for Maternal Phenylketonuria.

OBJECTIVES: The purpose of this study was to measure the effectiveness of resource mothers in reducing adverse consequences of maternal phenylketonuria. METHODS: Nineteen pregnancies in the resource mothers group were compared with 64 pregnancies in phenylketonuric women without resource mothers. Weeks to metabolic control and offspring outcome were measured. RESULTS: Mean number of weeks to metabolic control was 8.5 (SE = 2.2) in the resource mothers group, as compared with 16.1 (SE = 1.7) in the comparison group. Infants of women in the resource mothers group had larger birth head circumferences and higher developmental quotients. CONCLUSIONS: The resource mothers program described here improves metabolic control in pregnant women with phenylketonuria.

[An experimental study on the effects of maternal hyperphenylalaninemia on the central nervous system and behavior of offspring rats]. / Estudio experimental sobre los efectos de la hiperfenilalaninemia materna en el sistema nervioso central y la conducta de ratas hijas.

OBJECTIVE: This work attempts to study the cerebral alterations in rat offspring of hyperphenylalaninemic mothers, as well as the possibility of preventing them by means of administration of dietetic supplements of valine, leucine and isoleucine during the pregnancy. PATIENTS AND METHODS: An experimental study in two consecutive pregnancies of 18 Wistar rats was carried out. The first pregnancy serves as the control group. In the second pregnancy, an experimental hyperphenylalaninemia was provoked by means of injection of phenylalanine and chlorophenylalanine (phenylalanine-hydroxylase inhibitor). In half of the mothers during the second pregnancy the diet was supplemented with branched-chain amino acids. In the offspring rats, a histological cerebral study was performed (conventional electron microscopy and study of synaptosomes). A behavioral study (T-water maze) was also performed at birth and on the 35th and 65th days of life. RESULTS: The offspring of the group submitted to hyperphenylalaninemia were microcephalic (p = 0.0003) and had fewer synaptosomes that had a larger surface area (p = 0.0081 in newborn rats, p = 0.0028 on the 35th day of life) and of a more immature aspect (less vesicular content). In addition, alteration in the myelinization were detected. In the behavior test (65th day of life), the offspring of the mothers with hyperphenylalaninemia make significantly more mistakes (p = 0.0167) and they needed more time for their resolution (p = 0.059). None of these alterations could be prevented by the administration of supplements of branched-chain amino acids to the mother. These supplements resulted in a higher fertility rate, but this action results in affected young rats, so their administration seems to be counter-productive.

[Maternal PKU syndrome as an obstetric problem: literature review and own clinical experience]. / Zespól fenyloketonurii matczynej jako problem polozniczy--przedstawienie wspólczesnych pogladów i wlasnych doswiadczen klinicznych.

Maternal phenylketonuria (M-PKU) is a syndrome of embryo- and fetopathy observed in the offsprings of mothers with increased blood level of phenylalanine. These women fall into two groups: phenylketonuria (PKU) and mild hyperphenylalaninemia (MHP). The Phe--level safe for the fetus is 4-6 mg%. Typical for M-PKU syndrome is: microcephalia, mental retardation, intrauterine growth retardation, congenital heart diseases and other anomalies like esophageal atresia, meningocoele, Pierre-Robin syndrome, cataract. The only way to prevent this syndrome is Phe--restricted diet that should be initiated before conception. We reviewed updated literature on the pathogenesis of this syndrome, clinic, possibility of prophylaxis and treatment. We present also 5 pregnancies of 3 patients with PKU, treated in National Research Institute of Mother and Child in Warsaw. On that ground we propose the scheme of prevention of maternal PKU syndrome.

Keeping phenylketonuria under control.

The treatment of phenylketonuria (PKU) is one of the great success stories of modern medicine. It is likely that midwives will increasingly have more contact with women having PKU or giving birth to an infant with the condition. It is therefore important to have a good understanding of all aspects of PKU. Midwives can offer valuable support to parents whose children are found to have PKU. Maternal PKU is a major consideration as the benefits of screening in one generation may be lost in the next unless preventive treatment is appropriately implemented. PKU is one of the few conditions where effective screening and treatment can be measured.