Phenylalanine loading as a diagnostic test for DRD: Interpreting the utility of the test

R. Saunders-Pullman; N. Blau; K. Hyland; J. Zschocke; T. Nygaard; D. Raymond; V. Shanker; K. Mohrmann; L. Arnold; S. Tabbal; D. Deleon; B. Ford; M. Brin; S. Chouinard; L. Ozelius; C. Klein; S. B. Bressman

doi:10.1016/j.ymgme.2004.07.010

Phenylalanine loading as a diagnostic test for DRD: Interpreting the utility of the test

R. Saunders-Pullman, N. Blau, K. Hyland, J. Zschocke, T. Nygaard, D. Raymond, V. Shanker, K. Mohrmann, L. Arnold, S. Tabbal, D. Deleon, B. Ford, M. Brin, S. Chouinard, L. Ozelius, C. Klein, S. B. Bressman

Institute of Neurogenetics

34 Citations (Scopus)

Abstract

Phenylalanine loading has been proposed as a diagnostic test for autosomal dominant DRD (dopa-responsive dystonia), and recently, a phenylalanine/tyrosine (phe/tyr) ratio of 7.5 after 4 h was reported as diagnostic of DRD. To test the utility of this test in another sample with DRD, we administered an oral challenge of phenylalanine (100 mg/kg) to 11 individuals with DRD and one non-manifesting gene carrier. Only 6/12 had a 4 h phe/tyr ratio of greater than 7.5, suggesting that additional parameters must be set to avoid missing the diagnosis of DRD, including the need for the plasma phenylalanine to reach a minimum level 600 in order for the test to be valid. We propose that in cases where this minimum plasma phenylalanine level is not reached, plasma tetrahydrobiopterin should be measured or alternatively other symptomatic family members should be screened.

Original language	English
Journal	Molecular Genetics and Metabolism
Volume	83
Issue number	3
Pages (from-to)	207-212
Number of pages	6
ISSN	1096-7192
DOIs	https://doi.org/10.1016/j.ymgme.2004.07.010
Publication status	Published - 01.11.2004

Funding

The authors thank the families who have graciously participated in this study. This study was supported in part by the Dystonia Medical Research Foundation (RSP, SBB), the Nell and Herbert Singer Fund (RSP), by the Swiss National Science Foundation, Grant No. 31-66953.01 (NB), by the Medical University of Luebeck, Grant No. J-15 (CK), and the Fritz Thyssen Stiftung (CK).

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 3 Good Health and Well-being

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Saunders-Pullman, R., Blau, N., Hyland, K., Zschocke, J., Nygaard, T., Raymond, D., Shanker, V., Mohrmann, K., Arnold, L., Tabbal, S., Deleon, D., Ford, B., Brin, M., Chouinard, S., Ozelius, L., Klein, C., & Bressman, S. B. (2004). Phenylalanine loading as a diagnostic test for DRD: Interpreting the utility of the test. Molecular Genetics and Metabolism, 83(3), 207-212. https://doi.org/10.1016/j.ymgme.2004.07.010

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abstract = "Phenylalanine loading has been proposed as a diagnostic test for autosomal dominant DRD (dopa-responsive dystonia), and recently, a phenylalanine/tyrosine (phe/tyr) ratio of 7.5 after 4 h was reported as diagnostic of DRD. To test the utility of this test in another sample with DRD, we administered an oral challenge of phenylalanine (100 mg/kg) to 11 individuals with DRD and one non-manifesting gene carrier. Only 6/12 had a 4 h phe/tyr ratio of greater than 7.5, suggesting that additional parameters must be set to avoid missing the diagnosis of DRD, including the need for the plasma phenylalanine to reach a minimum level 600 in order for the test to be valid. We propose that in cases where this minimum plasma phenylalanine level is not reached, plasma tetrahydrobiopterin should be measured or alternatively other symptomatic family members should be screened.",

author = "R. Saunders-Pullman and N. Blau and K. Hyland and J. Zschocke and T. Nygaard and D. Raymond and V. Shanker and K. Mohrmann and L. Arnold and S. Tabbal and D. Deleon and B. Ford and M. Brin and S. Chouinard and L. Ozelius and C. Klein and Bressman, \{S. B.\}",

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Saunders-Pullman, R, Blau, N, Hyland, K, Zschocke, J, Nygaard, T, Raymond, D, Shanker, V, Mohrmann, K, Arnold, L, Tabbal, S, Deleon, D, Ford, B, Brin, M, Chouinard, S, Ozelius, L, Klein, C & Bressman, SB 2004, 'Phenylalanine loading as a diagnostic test for DRD: Interpreting the utility of the test', Molecular Genetics and Metabolism, vol. 83, no. 3, pp. 207-212. https://doi.org/10.1016/j.ymgme.2004.07.010

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T1 - Phenylalanine loading as a diagnostic test for DRD: Interpreting the utility of the test

AU - Saunders-Pullman, R.

AU - Blau, N.

AU - Hyland, K.

AU - Zschocke, J.

AU - Nygaard, T.

AU - Raymond, D.

AU - Shanker, V.

AU - Mohrmann, K.

AU - Arnold, L.

AU - Tabbal, S.

AU - Deleon, D.

AU - Ford, B.

AU - Brin, M.

AU - Chouinard, S.

AU - Ozelius, L.

AU - Klein, C.

AU - Bressman, S. B.

PY - 2004/11/1

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N2 - Phenylalanine loading has been proposed as a diagnostic test for autosomal dominant DRD (dopa-responsive dystonia), and recently, a phenylalanine/tyrosine (phe/tyr) ratio of 7.5 after 4 h was reported as diagnostic of DRD. To test the utility of this test in another sample with DRD, we administered an oral challenge of phenylalanine (100 mg/kg) to 11 individuals with DRD and one non-manifesting gene carrier. Only 6/12 had a 4 h phe/tyr ratio of greater than 7.5, suggesting that additional parameters must be set to avoid missing the diagnosis of DRD, including the need for the plasma phenylalanine to reach a minimum level 600 in order for the test to be valid. We propose that in cases where this minimum plasma phenylalanine level is not reached, plasma tetrahydrobiopterin should be measured or alternatively other symptomatic family members should be screened.

AB - Phenylalanine loading has been proposed as a diagnostic test for autosomal dominant DRD (dopa-responsive dystonia), and recently, a phenylalanine/tyrosine (phe/tyr) ratio of 7.5 after 4 h was reported as diagnostic of DRD. To test the utility of this test in another sample with DRD, we administered an oral challenge of phenylalanine (100 mg/kg) to 11 individuals with DRD and one non-manifesting gene carrier. Only 6/12 had a 4 h phe/tyr ratio of greater than 7.5, suggesting that additional parameters must be set to avoid missing the diagnosis of DRD, including the need for the plasma phenylalanine to reach a minimum level 600 in order for the test to be valid. We propose that in cases where this minimum plasma phenylalanine level is not reached, plasma tetrahydrobiopterin should be measured or alternatively other symptomatic family members should be screened.

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Phenylalanine loading as a diagnostic test for DRD: Interpreting the utility of the test

Abstract

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