Timing of cerebral developmental disruption in molybdenum cofactor deficiency

Fosdenopterin: a First-in-class Synthetic Cyclic Pyranopterin Monophosphate for the Treatment of Molybdenum Cofactor Deficiency Type A

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Prenatal brain disruption in isolated sulfite oxidase deficiency

Background

Isolated sulfite oxidase deficiency (ISOD) is a very rare autosomal recessive inherited neurometabolic disease. The most striking postnatal neuroimaging finding is multicystic encephalomalacia, which occurs rapidly within days to weeks after birth and mimics severe hypoxic-ischemic encephalopathy. The aim of this study was to describe the prenatal neuroimaging features in a neonate and a fetus diagnosed with ISOD.

Results

We report an 11-day-old female neonate who presented with feeding difficulties, decreased activity, neonatal seizures, and movement disorders within a few days after birth. Brain MRI at 9 days of age showed cystic lesions over the left frontal and temporal areas, diffuse and evident T2 high signal intensity of bilateral cerebral cortex, and increased T2 signal intensity of the globus pallidi. A pronounced low level of plasma cysteine and normal level of plasma uric acid were noted. Mutation analysis of SUOX revealed homozygous c.1200C > G mutations, resulting in an amino acid substitution of tyrosine to a stop codon (Y400X). The diagnosis of ISOD was made. The brain MRI of a prenatally diagnosed ISOD fetus of the second pregnancy of the mother of the index case showed poor gyration and differentiation of cortical layers without formation of cystic lesions at gestational age 21 weeks.

Conclusion

Cystic brain destruction might occur prenatally and neurodevelopment of gyration and differentiation of the cortical layers in the developing brain could be affected by sulfite accumulation early during the second trimester in ISOD patients. This is the first description of the prenatal neurodevelopment of brain disruption in ISOD.

Efficacy and safety of cyclic pyranopterin monophosphate substitution in severe molybdenum cofactor deficiency type A: a prospective cohort study

BACKGROUND

Molybdenum cofactor deficiency (MoCD) is characterised by early, rapidly progressive postnatal encephalopathy and intractable seizures, leading to severe disability and early death. Previous treatment attempts have been unsuccessful. After a pioneering single treatment we now report the outcome of the complete first cohort of patients receiving substitution treatment with cyclic pyranopterin monophosphate (cPMP), a biosynthetic precursor of the cofactor.

METHODS

In this observational prospective cohort study, newborn babies with clinical and biochemical evidence of MoCD were admitted to a compassionate-use programme at the request of their treating physicians. Intravenous cPMP (80-320 μg/kg per day) was started in neonates diagnosed with MoCD (type A and type B) following a standardised protocol. We prospectively monitored safety and efficacy in all patients exposed to cPMP.

FINDINGS

Between June 6, 2008, and Jan 9, 2013, intravenous cPMP was started in 16 neonates diagnosed with MoCD (11 type A and five type B) and continued in eight type A patients for up to 5 years. We observed no drug-related serious adverse events after more than 6000 doses. The disease biomarkers urinary S-sulphocysteine, xanthine, and urate returned to almost normal concentrations in all type A patients within 2 days, and remained normal for up to 5 years on continued cPMP substitution. Eight patients with type A disease rapidly improved under treatment and convulsions were either completely suppressed or substantially reduced. Three patients treated early remain seizure free and show near-normal long-term development. We detected no biochemical or clinical response in patients with type B disease.

INTERPRETATION

cPMP substitution is the first effective therapy for patients with MoCD type A and has a favourable safety profile. Restoration of molybdenum cofactor-dependent enzyme activities results in a greatly improved neurodevelopmental outcome when started sufficiently early. The possibility of MoCD type A needs to be urgently explored in every encephalopathic neonate to avoid any delay in appropriate cPMP substitution, and to maximise treatment benefit.

FUNDING

German Ministry of Education and Research; Orphatec/Colbourne Pharmaceuticals.

Early features in neuroimaging of two siblings with molybdenum cofactor deficiency

We report the features of neuroimaging within 24 hours after birth in 2 siblings with molybdenum cofactor deficiency. The first sibling was delivered by emergency cesarean section because of fetal distress and showed pedaling and crawling seizures soon after birth. Brain ultrasound revealed subcortical multicystic lesions in the frontal white matter, and brain MRI at 4 hours after birth showed restricted diffusion in the entire cortex, except for the area adjacent to the subcortical cysts. The second sibling was delivered by elective cesarean section. Cystic lesions were seen in the frontal white matter on ultrasound, and brain MRI showed low signal intensity on T1-weighted image and high signal intensity on T2-weighted image in bifrontal white matter within 24 hours after birth, at which time the infant sucked sluggishly. Clonic spasm appeared at 29 hours after birth. The corpus callosum could not be seen clearly on ultrasound or MRI in both infants. Cortical atrophy and white matter cystic lesions spread to the entire hemisphere and resulted in severe brain atrophy within ~1 month in both infants. Subcortical multicystic lesions on ultrasound and a cortex with nonuniform, widespread, restricted diffusion on diffusion-weighted images are early features of neuroimaging in patients with molybdenum cofactor deficiency type A.

Favorable outcome in a newborn with molybdenum cofactor type A deficiency treated with cPMP

Molybdenum cofactor deficiency (MoCD) is a lethal autosomal recessive inborn error of metabolism with devastating neurologic manifestations. Currently, experimental treatment with cyclic pyranopterin monophosphate (cPMP) is available for patients with MoCD type A caused by a mutation in the MOCS-1 gene. Here we report the first case of an infant, prenatally diagnosed with MoCD type A, whom we started on treatment with cPMP 4 hours after birth. The most reliable method to evaluate neurologic functioning in early infancy is to assess the quality of general movements (GMs) and fidgety movements (FMs). After a brief period of seizures and cramped-synchronized GMs on the first day, our patient showed no further clinical signs of neurologic deterioration. Her quality of GMs was normal by the end of the first week. Rapid improvement of GM quality together with normal FMs at 3 months is highly predictive of normal neurologic outcome. We demonstrated that a daily cPMP dose of even 80 μg/kg in the first 12 days reduced the effects of neurodegenerative damage even when seizures and cramped-synchronized GMs were already present. We strongly recommend starting cPMP treatment as soon as possible after birth in infants diagnosed with MoCD type A.