Long‐term outcome and neuroradiological findings of 31 patients with 6‐pyruvoyltetrahydropterin synthase deficiency

Abstract

Tetrahydrobiopterin (BH(4)) deficiency is an autosomal recessive disorder caused by enzyme defects in the biosynthesis or recycling of BH(4). Patients with BH(4) deficiency present with severe neurological signs and symptoms and require a different treatment from classical phenylketonuria. During the last 12 years, 31 cases of BH(4) deficiency were identified in our department. They were all classified as 6-pyruvoyl-tetrahydropterin synthase (PTPS) deficiency. They were diagnosed at the ages of 2.5-48 months and treated with BH(4), L-dopa and 5-hydroxytryptophan immediately after diagnosis. The average development quotients (DQ) at diagnosis and after treatment for more than 3 years were 53+/- 16, and 78+/- 15, respectively. A significant negative correlation was observed between the level of the DQ and the age at which treatment was commenced (r = -0.751, p = 0.002). Developmental profiles were uneven. Language, adaptability and at later age mathematics were particularly weak areas. Only two patients achieved a good performance in mathematics. Eleven patients who were treated with drugs from ages of 2.9-48 months had neuroradiological scanning. Computed tomography disclosed calcification in lentiform nuclei in one patient and magnetic resonance imaging disclosed delayed myelination and abnormal high intensity signal in cerebral white matter in all of them. Even though most of abnormalities were reversible, small patchy or spotted areas were still present on these regions after treatment for 10-46 months. In summary, our study supports the substantial efficacy of the current therapeutic approach in PTPS deficiency of normalizing amine neurotransmitters with three drugs as early as possible. For the first time, calcifications could be detected in patients with PTPS deficiency. Abnormalities in white matter on magnetic resonance imaging were not related to clinical manifestations and most were reversible.

An international survey of patients with tetrahydrobiopterin deficiencies presenting with hyperphenylalaninaemia

“…Cerebral atrophy is observed on cranial CTs in many DHPR-and PTPS-deficient patients. Apart from one Chinese PTPS-deficient patient, basal ganglia calcifications have only been seen in DHPR deficiency (Woody et al 1989) and have been shown to be reversible under treatment (Wang et al 2006).…”

Molecular Characterization of QDPR Gene in Iranian Families with BH4 Deficiency: Reporting Novel and Recurrent Mutations

“…So BH4 deficiency can also leads to defect in neurotransmitters. As a result, BH4-deficient patients show neurological deterioration when they are only treated with phenyl restricted diet (Wang et al 2006). So the differential diagnosis of the BH4 deficiency from phenylketonuria (PKU, MIM 261600) is very essential and should be initiated as soon as possible to reduce neurological impairment in the affected individuals.…”

Tetrahydrobiopterin treatment in phenylketonuria: A repurposing approach

“…A possible relationship between BH 4 supplementation and improved myelination has been described in BH 4 deficiency patients . When comparing their own results with a previous study on myelination in BH 4 deficiency patients, Wang et al showed more white matter abnormalities. In contrast to these differences in neuroradiological findings, age at which dietary treatment was initiated was comparable for both patient groups.…”