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Hoss GRW, Sperb-Ludwig F, Tonon T, Poloni S, Behringer S, Blom HJ, Maillot F, Schwartz IVD. Homocysteine and methylmalonic acid in Phenylketonuria patients. Genet Mol Biol 2024; 46:e20230103. [PMID: 38591937 PMCID: PMC11000623 DOI: 10.1590/1678-4685-gmb-2023-0103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 02/10/2024] [Indexed: 04/10/2024] Open
Abstract
Hyperhomocysteinemia and vitamin B12 deficiency have been reported in patients with phenylketonuria. In this study, total homocysteine (tHcy) and methylmalonic acid (MMA) levels were analyzed in samples from 25 phenylketonuria (PKU) patients. Comparisons were made between pre- and post-treatment values (n= 3); on treatment values, between periods with high and normal/low phenylalanine (Phe) levels (n= 20); and in women before, during and after pregnancy (n= 3). THcy levels decreased after treating PKU with metabolic formula (p=0.014). Except for a pregnant woman before pregnancy, none of the patients had tHcy values above the normal range. In fact, tHcy was < 5 μmol/L in 34% of the samples. We observed a decrease in Phe, tHcy, and tyrosine levels during pregnancy. MMA levels did not differ significantly, with values remaining in the normal range. These data indicate that there was no B12 deficiency in patients who adhere to the diet. In conclusion, in PKU patients treated with metabolic formula, tHcy is frequently not elevated, remaining even in the lower normal range in some patients. Thus, clinical follow-up and adherence to dietary treatment are crucial to prevent B12 deficiency.
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Affiliation(s)
- Giovana Regina Weber Hoss
- Hospital de Clínicas de Porto Alegre, Laboratório BRAIN, Porto
Alegre, RS, Brazil
- Universidade Federal do Rio Grande do Sul (UFRGS), Programa de
Pós-Graduação em Genética e Biologia Molecular, Porto Alegre, RS, Brazil
| | - Fernanda Sperb-Ludwig
- Hospital de Clínicas de Porto Alegre, Laboratório BRAIN, Porto
Alegre, RS, Brazil
- Universidade Federal do Rio Grande do Sul (UFRGS), Programa de
Pós-Graduação em Genética e Biologia Molecular, Porto Alegre, RS, Brazil
| | - Tássia Tonon
- Hospital de Clínicas de Porto Alegre, Laboratório BRAIN, Porto
Alegre, RS, Brazil
| | - Soraia Poloni
- Hospital de Clínicas de Porto Alegre, Laboratório BRAIN, Porto
Alegre, RS, Brazil
| | - Sidney Behringer
- University Medical Centre, Laboratory of Clinical Biochemistry and
Metabolism, Freiburg, Germany
| | - Henk J. Blom
- Erasmus Universiteit Rotterdam, Laboratory of Clinical Genetics, The
Netherlands
| | - François Maillot
- University Hospital of Tours, Department of Internal Medicine,
Tours, France
- UMR INSERM 1253, Tours, France
- Reference Center for Inherited Metabolic Diseases, Tours,
France
| | - Ida Vanessa Doederlein Schwartz
- Hospital de Clínicas de Porto Alegre, Laboratório BRAIN, Porto
Alegre, RS, Brazil
- Universidade Federal do Rio Grande do Sul (UFRGS), Programa de
Pós-Graduação em Genética e Biologia Molecular, Porto Alegre, RS, Brazil
- Hospital de Clínicas de Porto Alegre, Serviço de Genética Médica,
Porto Alegre, RS, Brazil
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Akış M, Kant M, Işık İ, Kısa PT, Köse E, Arslan N, İşlekel H. Functional vitamin B12 deficiency in phenylketonuria patients and healthy controls: An evaluation with combined indicator of vitamin B12 status as a biochemical index. Ann Clin Biochem 2020; 57:291-299. [PMID: 32482081 DOI: 10.1177/0004563220935140] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Vitamin B12 deficiency frequently appears in phenylketonuria patients having a diet poor in natural protein. The aims of this study were to evaluate vitamin B12 status in phenylketonuria patients by using combined indicator of vitamin B12 status (cB12) as well as methylmalonic acid and homocysteine, more specific and sensitive markers, in comparison with healthy controls. METHODS Fifty-three children and adolescents with phenylketonuria under dietary treatment and 30 healthy controls were assessed cross-sectionally. Serum vitamin B12 and folate concentrations were analysed by chemiluminescence immunoassay. Plasma methylmalonic acid and total homocysteine concentrations were measured by liquid chromatography-tandem mass spectrometry and liquid chromatography, respectively. cB12 was calculated by using a formula involving blood parameters. RESULTS Methylmalonic acid and folate concentrations in phenylketonuria group were higher compared with controls. Methylmalonic acid concentrations were high in 56.5% of the patients and 26.7% of the controls with normal vitamin B12 concentrations. Based on cB12, a significant difference within the normal values was detected between the groups. However, although 24.5% of phenylketonuria patients and 13.3% of controls had decreased vitamin B12 status according to cB12, there was no significant difference. CONCLUSION Children and adolescents with phenylketonuria having a strict diet can be at risk of functional vitamin B12 deficiency. This deficiency can be accurately determined by measuring methylmalonic acid concentrations. Calculation of cB12 as a biochemical index did not provide additional information compared with the measurement of methylmalonic acid alone, but may be helpful for classification of some patients with increased methylmalonic acid as having adequate vitamin B12 status.
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Affiliation(s)
- Merve Akış
- Department of Medical Biochemistry, School of Medicine, Balikesir University, Balikesir, Turkey
| | - Melis Kant
- Department of Medical Biochemistry, Institute of Health Sciences, School of Medicine, Dokuz Eylul University, Izmir, Turkey
| | - İshak Işık
- Department of Pediatric Gastroenterology, Hepatology and Nutrition, Health Sciences University Antalya Training and Research Hospital, Antalya, Turkey
| | - Pelin Teke Kısa
- Division of Pediatric Metabolism and Nutrition, Dokuz Eylul University, Izmir, Turkey
| | - Engin Köse
- Division of Pediatric Metabolism and Nutrition, Dokuz Eylul University, Izmir, Turkey
| | - Nur Arslan
- Division of Pediatric Metabolism and Nutrition, Dokuz Eylul University, Izmir, Turkey
| | - Hüray İşlekel
- Department of Medical Biochemistry, School of Medicine, Dokuz Eylul University, Izmir, Turkey.,Department of Molecular Medicine, Institute of Health Sciences, Dokuz Eylul University, Izmir, Turkey
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Wild J, Shanmuganathan M, Hayashi M, Potter M, Britz-McKibbin P. Metabolomics for improved treatment monitoring of phenylketonuria: urinary biomarkers for non-invasive assessment of dietary adherence and nutritional deficiencies. Analyst 2020; 144:6595-6608. [PMID: 31608347 DOI: 10.1039/c9an01642b] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Management of phenylketonuria (PKU) requires lifelong restriction of phenylalanine (Phe) intake using specialized medical foods to prevent neurocognitive impairment in affected patients. However, dietary adherence is challenging to maintain while ensuring adequate nutrition, which can lead to sub-optimal clinical outcomes. Metabolomics offers a systematic approach to identify new biomarkers of disease progression in PKU when using urine as a surrogate for blood specimens that is more accurate than self-reported diet records. Herein, the plasma and urine metabolome of a cohort of classic PKU patients (median age = 11 years; n = 22) mainly prescribed (78%) a Phe-restricted diet were characterized using multisegment injection-capillary electrophoresis-mass spectrometry (MSI-CE-MS). Overall, there was good mutual agreement between plasma Phe and tyrosine (Tyr) concentrations measured from PKU patients when using an amino acid analyzer based on UPLC-UV as compared to MSI-CE-MS with a mean bias of 12% (n = 82). Longitudinal measurements of recently diagnosed PKU infants (n = 3) revealed good long-term regulation of blood Phe with dietary management, and only occasional episodes exceeding the recommended therapeutic range (>360 μM) unlike older PKU patients. Plasma metabolomic studies demonstrated that non-adherent PKU patients had lower circulating concentrations of Tyr, arginine, 2-aminobutyric acid, and propionylcarnitine (q < 0.05, FDR) that were inversely correlated to Phe (r ≈ -0.600 to -0.830). Nontargeted metabolite profiling also revealed urinary biomarkers associated with poor dietary adherence among PKU patients, including elevated concentrations of catabolites indicative of Phe intoxication (e.g., phenylpyruvic acid, phenylacetylglutamine, hydroxyphenylacetic acid). Additionally, PKU patients with poor blood Phe control had lower excretion of urinary compounds derived from co-metabolism of Tyr due to microbiota activity (e.g., cresol sulfate, phenylsulfate), as well as several metabolites associated with inadequate nutrient intake, including low carnitine and B vitamin status (e.g., folic acid, vitamin B12). Interestingly, an unknown urinary metabolite was strongly correlated with Phe excretion in PKU patients (r = 0.861), which was subsequently identified as imidazole lactic acid when using high resolution MS/MS. Overall, urine profiling offers a non-invasive approach for better treatment monitoring of individual PKU patients, which can also guide the design of novel therapies that improve adherence to Phe-restricted diets without acquired nutritional deficiencies.
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Affiliation(s)
- Jennifer Wild
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario, Canada.
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