Zika-exposed microcephalic neonates exhibit higher degree of inflammatory imbalance in cerebrospinal fluid.

Not every neonate with congenital Zika virus (ZIKV) infection (CZI) is born with microcephaly. We compared inflammation mediators in CSF (cerebrospinal fluid obtained from lumbar puncture) between ZIKV-exposed neonates with/without microcephaly (cases) and controls. In Brazil, in the same laboratory, we identified 14 ZIKV-exposed neonates during the ZIKV epidemic (2015-2016), 7(50%) with and 7(50%) without microcephaly, without any other congenital infection, and 14 neonates (2017-2018) eligible to be controls and to match cases. 29 inflammation mediators were measured using Luminex immunoassay and multidimensional analyses were employed. Neonates with ZIKV-associated microcephaly presented substantially higher degree of inflammatory perturbation, associated with uncoupled inflammatory response and decreased correlations between concentrations of inflammatory biomarkers. The groups of microcephalic and non-microcephalic ZIKV-exposed neonates were distinguished from the control group (area under curve [AUC] = 1; P < 0.0001). Between controls and those non-microcephalic exposed to ZIKV, IL-1ß, IL-3, IL-4, IL-7 and EOTAXIN were the top CSF markers. By comparing the microcephalic cases with controls, the top discriminant scores were for IL-1ß, IL-3, EOTAXIN and IL-12p70. The degree of inflammatory imbalance may be associated with microcephaly in CZI and it may aid additional investigations in experimental pre-clinical models testing immune modulators in preventing extensive damage of the Central Nervous System.

5,10-methenyltetrahydrofolate synthetase deficiency causes a neurometabolic disorder associated with microcephaly, epilepsy, and cerebral hypomyelination.

Folate metabolism in the brain is critically important and serves a number of vital roles in nucleotide synthesis, single carbon metabolism/methylation, amino acid metabolism, and mitochondrial translation. Genetic defects in almost every enzyme of folate metabolism have been reported to date, and most have neurological sequelae. We report 2 patients presenting with a neurometabolic disorder associated with biallelic variants in the MTHFS gene, encoding 5,10-methenyltetrahydrofolate synthetase. Both patients presented with microcephaly, short stature, severe global developmental delay, progressive spasticity, epilepsy, and cerebral hypomyelination. Baseline CSF 5-methyltetrahydrolate (5-MTHF) levels were in the low-normal range. The first patient was treated with folinic acid, which resulted in worsening cerebral folate deficiency. Treatment in this patient with a combination of oral L-5-methyltetrahydrofolate and intramuscular methylcobalamin was able to increase CSF 5-MTHF levels, was well tolerated over a 4 month period, and resulted in subjective mild improvements in functioning. Measurement of MTHFS enzyme activity in fibroblasts confirmed reduced activity. The direct substrate of the MTHFS reaction, 5-formyl-THF, was elevated 30-fold in patient fibroblasts compared to control, supporting the hypothesis that the pathophysiology of this disorder is a manifestation of toxicity from this metabolite.

An update on serine deficiency disorders.

Serine deficiency disorders are caused by a defect in one of the three synthesising enzymes of the L-serine biosynthesis pathway. Serine deficiency disorders give rise to a neurological phenotype with psychomotor retardation, microcephaly and seizures in newborns and children or progressive polyneuropathy in adult patients. There are three defects that cause serine deficiency of which 3-phosphoglycerate dehydrogenase (3-PGDH) deficiency, the defect affecting the first step in the pathway, has been reported most frequently. The other two disorders in L-serine biosynthesis phosphoserine aminotransferase (PSAT) deficiency and phosphoserine phosphatase (PSP) deficiency have been reported only in a limited number of patients. The biochemical hallmarks of all three disorders are low concentrations of serine in cerebrospinal fluid and plasma. Prompt recognition of affected patients is important, since serine deficiency disorders are treatable causes of neurometabolic disorders. The use of age-related reference values for serine in CSF and plasma can be of great help in establishing a correct diagnosis of serine deficiency, in particular in newborns and young children.

Pontocerebellar hypoplasia type 6 caused by mutations in RARS2: definition of the clinical spectrum and molecular findings in five patients.

Recessive mutations in the mitochondrial arginyl-transfer RNA synthetase (RARS2) gene have been associated with early onset encephalopathy with signs of oxidative phosphorylation defects classified as pontocerebellar hypoplasia 6. We describe clinical, neuroimaging and molecular features on five patients from three unrelated families who displayed mutations in RARS2. All patients rapidly developed a neonatal or early-infantile epileptic encephalopathy with intractable seizures. The long-term follow-up revealed a virtual absence of psychomotor development, progressive microcephaly, and feeding difficulties. Mitochondrial respiratory chain enzymes in muscle and fibroblasts were normal in two. Blood and CSF lactate was abnormally elevated in all five patients at early stages while appearing only occasionally abnormal with the progression of the disease. Cerebellar vermis hypoplasia with normal aspect of the cerebral and cerebellar hemispheres appeared within the first months of life at brain MRI. In three patients follow-up neuroimaging revealed a progressive pontocerebellar and cerebral cortical atrophy. Molecular investigations of RARS2 disclosed the c.25A>G/p.I9V and the c.1586+3A>T in family A, the c.734G>A/p.R245Q and the c.1406G>A/p.R469H in family B, and the c.721T>A/p.W241R and c.35A>G/p.Q12R in family C. Functional complementation studies in Saccharomyces cerevisiae showed that mutation MSR1-R531H (equivalent to human p.R469H) abolished respiration whereas the MSR1-R306Q strain (corresponding to p.R245Q) displayed a reduced growth on non-fermentable YPG medium. Although mutations functionally disrupted yeast we found a relatively well preserved arginine aminoacylation of mitochondrial tRNA. Clinical and neuroimaging findings are important clues to raise suspicion and to reach diagnostic accuracy for RARS2 mutations considering that biochemical abnormalities may be absent in muscle biopsy.

[Diagnostic value of the CSF uric acid level (author's transl)].

Uric acid is the end-product of purine metabolism, and purines are the nitrogenous bases derived from the breakdown of nucleic acids. The CSF uric acid level is thought to be the index of the turnover of the nucleic acid and the degree of the cellular destruction in the brain. CSF uric acid levels were investigated in normal controls (30 cases) and in patients with brain tumor (20 cases), microcephalus (8 cases) and craniostenosis (4 cases). The mean values and standard deviations of CSF uric acid levels in normal controls were as follows; Newborn--9 yrs 0.34 +/- 0.09 mg/dl; 10 yrs--19 yrs 0.50 +/- 0.18 mg/dl; 20 yrs--29 yrs 0.46 +/- 0.05 mg/dl; 30 yrs--39 yrs 0.35 +/- 0.10 mg/dl; 40 yrs--49 yrs 0.35 +/- 0.23 mg/dl. Thereafter 0.72 +/- 0.21 mg/dl. The increased CSF uric acid levels after the age of 50 is thought to be due to the cellular destruction in the brain. CSF uric acid levels increased in patients with highly malignant brain tumor such as grade 3 or 4 astrocytoma and sarcomatous meningioma, but were normal in patients with grade 2 astrocytoma and meningiomas of meingothelial or fibroblastic type. CSF uric acid levels decreased in patients with microcephalus, but were almost normal in patients with craniostenosis. There is a significant correlation between CSF uric acid levels and the degree of brain atrophy in infants.