Causes for High Phenylalanine With Normal Tyrosine

Berman, Julian L.; Cunningham, George C.; Day, Robert W.; Ford, Robin C.; Hsia, David Yi‐Yung

doi:10.1001/archpedi.1969.02100030056006

Cited by 48 publications

(9 citation statements)

References 13 publications

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“…Studies by Berman et al (1969), and Kang et al (1970 revealed no differences in the phenotypes of heterozygotes for PKU and heterozygotes for the variants ofPKU. One explanation for the discrepancy between these observations and the observation of Rosenblatt andScriver (1968), Jackson et al (1971), and the present study may be that different diagnostic criteria have been used.…”

Section: Phenotypic Combination Of Parents Related To the Phenotype Omentioning

confidence: 95%

“…One explanation for the discrepancy between these observations and the observation of Rosenblatt andScriver (1968), Jackson et al (1971), and the present study may be that different diagnostic criteria have been used. In the studies of Berman et al (1969), and Kang et al (1970 patients with classical PKU were characterised by a maximum blood phenylalanine level of 20 mg/l00 ml or higher, and the variants of PKU as patients in whom the maximum blood phenylalanine level has been less than 19.9 mg/l00 m!.…”

Section: Phenotypic Combination Of Parents Related To the Phenotype Omentioning

confidence: 99%

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Different Phenotypes for Phenylalanine Hydroxylase Deficiency

Güttler¹,

Hansen²

1977

Ann Clin Biochem

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Abnormalities related to the hydroxylation of phenylalanine to tyrosine are classified into three phenotypes based on the amount of dietary phenylalanine tolerated to keep serum phenylalanine within therapeutic levels,i.e., 180-425p.mol/l (3-7 mg/IOO ml): (I) Classical phenylketonuria (PKU) tolerating approximately 17% of a normal intake of phenylalanine or approximately 0.12 mmol per kg body weight; (2) mild PKU with a tolerance some 50% higher; and (3) persistent hyperphenylalaninaemia(HPA) with serum phenylalanine valueswithin therapeutic levelson a daily intake of ;;'0.7 mmol phenylalanine per kg body weight.Oral phenylalanine loading was performed on 100 heterozygotes for these abnormalities and 33 normal homozygotes. The slope of the rise in serum tyrosine multiplied by the maximum serum tyrosine concentration over the maximum phenylalanine concentration was the most powerful discriminant (Dis, 3.54; overlapping 2.4%). Three heterozygous phenotypes were distinguished by this discriminant, and a significant correlation was observed between the phenotypic combination of the parents and the phenotype of their affected child. In particular, parents of children with classical PKU were clearly distinguished from heterozygotes for the other two abnormalities.Abnormalities related to the hydroxylation of phenylalanine to tyrosine may be classified into at least three forms (Scriver, 1967;Cohen, 1973): (I) Classical phenylketonuria (PKU); (2) Variant hyperphenylalaninaemias, a mixed group including "mild" and "transient" PKU, where the decision and classification soon after birth may be difficult (Hsia, 1970;Blaskovics et al., 1974;Rosenberg and Scriver, 1974); (3) Persistent hyperphenylalaninaemia (HPA). The three forms of abnormalities have in common that a loading dose of phenylalanine fails to produce a significant rise in serum tyrosine (Guttler and Warn berg, 1972).Several investigations have established that early detection and treatment of infants with elevated blood phenylalanine is beneficial to intellectual development if the child suffers from PKU (cf. Wamberg, 1973;Rosenberg and Scriver, 1974). Early treatment implies, however, that classical clinical features will not be observed. Thus, the correct diagnosis must be based on other criteria. The present investigation shows that children with PKU may be classified into two forms according to their dietary tolerance of phenylalanine: (I) Classical PKU, tolerating approximately 17% of a normal dietary intake of phenylalanine, and (2) mild PKU, tolerating an intake of phenylalanine 50 % larger than that of the classical form. The course of serum phenylalanine after a phenylalanine loading test dose also differs in these two forms. The various forms of PKU may be distinguished from HPA, the latter condition being defined as showing (a) serum phenylalanine within generally accepted therapeutic levels, i.e., 180-425 fLmol/1 (3-7 mg/IOO ml) on a normal dietary intake of phenylalanine (Guttier and Correspondence to Dr. F. Guttier. John F. Kennedy Institute. G...

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Section: Phenotypic Combination Of Parents Related To the Phenotype Omentioning

confidence: 95%

Section: Phenotypic Combination Of Parents Related To the Phenotype Omentioning

confidence: 99%

Different Phenotypes for Phenylalanine Hydroxylase Deficiency

Güttler¹,

Hansen²

1977

Ann Clin Biochem

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“…In conjunction with the National Phenylketonuria Collaborative Study, some preliminary data of interest to those involved with interpretation of phenylalanine levels and tolerance tests was published in two papers, Berman et al (1969) and Cunningham et al (1969). These reports did not include a mathematical analysis of the data collected on blood phenylalanine (PA) and blood tyrosine (TY) tolerance tests.…”

Section: Methodsmentioning

confidence: 99%

“…A complete series of data was acquired for 177 parents of phenylketonuric infants, 40 parents of hyperphenylalanemic infants, and 29 controls. For a more detailed discussion of the loading methods and of the classification of cases, see the recent publications of Berman et al (1969) and Cunningham et al (1969). Linear discriminant functions were used to analyze the data because this analysis provides a means of assigning an individual to one of two populations.…”

Section: Methodsmentioning

confidence: 99%

Discriminant analysis for detection of phenylketonuric heterozygotes

Christian

1971

Social Biology

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“…However, several other reports support the possibility that the incidence of normal IQ in untreated PKU is higher than originally estimated. Berman (Berman et al, 1969) and Koch (Koch et al, 1971) tested all of the unscreened older siblings of PKU neonates diagnosed in the early days of newborn screening and each found 15 with undiagnosed/untreated PKU; four (27%) of Berman's and three (20%) of Koch's patients had normal IQ's. Levy (Levy et al, 1983) and Waisbren (Waisbren et al, 1984) tested 453,118 umbilical cord blood samples for PKU between 1971 and 1981 and found 22 previously undiagnosed, untreated, women with PKU.…”

Section: Untreated Pku With Normal Intellectual Function -The Puzzlementioning

confidence: 99%