Pregnancy management and outcome in patients with four different tetrahydrobiopterin disorders

The metabolic landscape of tetrahydrobiopterin metabolism disorders in the Republic of Ireland

We present a case series of seven patients (5 males, 2 females, aged 7-38 yrs.) in Ireland with biopterin metabolism disorder. Five individuals had been diagnosed with dihydropteridine reductase (DHPR) deficiency and two with pyruvoyl tetrahydropterin synthase (PTPS) deficiency. While clinical symptoms were mainly neuro-developmental in nature, one of our patients with DHPR deficiency also had a mild pulmonary valve stenosis and patent arterial duct in infancy which subsequently resolved as a hitherto undescribed finding in this condition. Clinical outcomes in our patient cohort were overall satisfactory with the best outcomes in patients/siblings diagnosed on high-risk screening. In conclusion, early diagnosis, pathophysiology-driven treatments and frequent patient-specific treatment adjustments are crucial to sustain the best possible long-term outcomes. Ireland's cohort of tetrahydropterin metabolism disorders highlights that improved outcomes are achieved with an early diagnosis which may not be attainable through newborn screening alone.

Insights into the expanding phenotypic spectrum of inherited disorders of biogenic amines

Inherited disorders of neurotransmitter metabolism are rare neurodevelopmental diseases presenting with movement disorders and global developmental delay. This study presents the results of the first standardized deep phenotyping approach and describes the clinical and biochemical presentation at disease onset as well as diagnostic approaches of 275 patients from the registry of the International Working Group on Neurotransmitter related Disorders. The results reveal an increased rate of prematurity, a high risk for being small for gestational age and for congenital microcephaly in some disorders. Age at diagnosis and the diagnostic delay are influenced by the diagnostic methods applied and by disease-specific symptoms. The timepoint of investigation was also a significant factor: delay to diagnosis has decreased in recent years, possibly due to novel diagnostic approaches or raised awareness. Although each disorder has a specific biochemical pattern, we observed confounding exceptions to the rule. The data provide comprehensive insights into the phenotypic spectrum of neurotransmitter disorders.

Inherited disorders of neurotransmitter metabolism represent a group of rare neurometabolic diseases characterized by movement disorders and developmental delay. Here, the authors report a standardized evaluation of a registry of 275 patients from 42 countries, and highlight an evolving phenotypic spectrum of this disease group and factors influencing diagnostic processes.

Consensus guideline for the diagnosis and treatment of tetrahydrobiopterin (BH4) deficiencies

BACKGROUND

Tetrahydrobiopterin (BH4) deficiencies comprise a group of six rare neurometabolic disorders characterized by insufficient synthesis of the monoamine neurotransmitters dopamine and serotonin due to a disturbance of BH4 biosynthesis or recycling. Hyperphenylalaninemia (HPA) is the first diagnostic hallmark for most BH4 deficiencies, apart from autosomal dominant guanosine triphosphate cyclohydrolase I deficiency and sepiapterin reductase deficiency. Early supplementation of neurotransmitter precursors and where appropriate, treatment of HPA results in significant improvement of motor and cognitive function. Management approaches differ across the world and therefore these guidelines have been developed aiming to harmonize and optimize patient care. Representatives of the International Working Group on Neurotransmitter related Disorders (iNTD) developed the guidelines according to the SIGN (Scottish Intercollegiate Guidelines Network) methodology by evaluating all available evidence for the diagnosis and treatment of BH4 deficiencies.

CONCLUSION

Although the total body of evidence in the literature was mainly rated as low or very low, these consensus guidelines will help to harmonize clinical practice and to standardize and improve care for BH4 deficient patients.