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. 2024 Apr 5;46(3 Suppl 1):e20230103.
doi: 10.1590/1678-4685-GMB-2023-0103. eCollection 2024.

Homocysteine and methylmalonic acid in Phenylketonuria patients

Giovana Regina Weber Hoss  1   2 , Fernanda Sperb-Ludwig  1   2 , Tássia Tonon  1 , Soraia Poloni  1 , Sidney Behringer  3 , Henk J Blom  4 , François Maillot  5   6   7 , Ida Vanessa Doederlein Schwartz  1   2   8
Affiliations

Homocysteine and methylmalonic acid in Phenylketonuria patients

Giovana Regina Weber Hoss et al. Genet Mol Biol. .

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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Conflict of interest statement

Conflict of Interest: The authors declare they have no conflicts of interest that could be perceived as prejudicial to the impartiality of the study.

Figures

Figure 1 -
Figure 1 -. Total homocysteine and methylmalonic acid in PKU patients before and after treatment.
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