MR study of the brain in patients with tetrahydrobiopterin deficiency / 中华放射学杂志

ABSTRACT

Objective To observe the brain abnormalities of the white matter and myelination in patients with BH4 deficiency using MRI examination, and to further estimate the effect of treatment. Methods Eleven patients with BH4 deficiency aged 17 weeks to 4 years were observed, including 9 cases who were detected by newborn screening program. Although those patients were treated with low phenylalanine diet, and the blood phenylalanine 1evels maintained to 120-240 ?mol/L, the patients presented progressive hypotonia, convulsion, and mental retardation. All cases were diagnosed as BH4 deficiency by analysis of urinary pterins profile, BH4 loading test, and determination of dihydropteridine reductase in RBC. The patients received MRI examination using a 0.5 T MR system. Results Delayed myelination was found in 11 cases (100%) in frontal lobe, 8 cases (72.2%) in occipital lobe, 4 cases (36.3%) in temporal lobe, and 3 cases (27.3%) in parietal lobe. Delayed myelination of corpus callosum could be found in 6 cases (54.5%). There were abnormal diffuse high signals in the white matter on T_2WI in all cases. Conclusion Patients with BH4 deficiency demonstrate a high occurrence of brain abnormalities in the white matter. Those abnormalities are related not only with hyperphenylalaninemia, but also due to the decreased synthesis of neurotransmitters, such as L-Dopa and 5-HTP, all of these could be the reasons of adverse effect of the development of white matter.