This article describes the first patient with a deficiency of transaldolase (TALDO1 [E.C.2.2.1.2]). Clinically, the patient presented with liver cirrhosis and hepatosplenomegaly during early infancy. In urine and plasma, elevated concentrations of ribitol, D-arabitol, and erythritol were found. By incubating the patient's lymphoblasts and erythrocytes with ribose-5-phosphate and subsequently analyzing phosphate sugar metabolites, we discovered a deficiency of transaldolase. Sequence analysis of the transaldolase gene from this patient showed a homozygous deletion of 3 bp. This deletion results in absence of serine at position 171 of the transaldolase protein. This amino acid is invariable between species and is located in a conserved region, indicating its importance for enzyme activity. The detection of this new inborn error of pentose metabolism has implications for the diagnostic workup of liver problems of unknown etiology.

No abstract

No abstract

Primary and secondary progressive forms of multiple sclerosis (PPMS and SPMS) have different pathological characteristics. However, it is unknown whether neurodegenerative mechanisms are shared. We measured cerebrospinal fluid (CSF) levels of neurofilament (Nf) light and heavy isoforms and N-acetylaspartic acid (NAA) in 21 PP, 10 SPMS patients and 15 non-inflammatory neurological disease controls (NINDC). Biomarkers were related to Expanded Disability Status Scale (EDSS) and Multiple Sclerosis Severity Score (MSSS) over a long period of follow-up [median (interquartile range) 9 (5.5-12.5) years] in 19 PPMS and 4 SPMS patients, and to T2 lesion load, T1 lesion load, and brain parenchymal fraction at the time of lumbar puncture. Nf light was higher in PPMS (p < 0.005) and Nf heavy was increased in both SPMS and PPMS (p < 0.05 and p < 0.01) compared to NINDC, but were comparable between the two MS subtypes. Nf heavy was a predictor of the ongoing disability measured by MSSS (R(2) = 0.17, β = 0.413; p < 0.05). Conversely, Nf light was the only predictor of the EDSS annual increase (R(2) = 0.195, β = 0.441; p < 0.05). The frequency of abnormal biomarkers did not differ between the two MS progressive subtypes. Our data suggest that PP and SPMS likely share similar mechanisms of axonal damage. Moreover, Nf heavy can be a biomarker of ongoing axonal damage. Conversely, Nf light can be used as a prognostic marker for accumulating disability suggesting it as a good tool for possible treatment monitoring in the progressive MS forms.

Metachromatic leukodystrophy is a lethal metabolic leukodystrophy, with emerging treatments for early disease stages. Biomarkers to measure disease activity are required for clinical assessment and treatment follow-up. This retrospective study compared neurofilament light chain and glial fibrillary acidic protein levels in CSF (n = 11) and blood (n = 92) samples of 40 patients with metachromatic leukodystrophy (aged 0–42 years) with 38 neurologically healthy children (aged 0–17 years) and 38 healthy adults (aged 18–45 years), and analyzed the associations between these levels with clinical phenotype and disease evolution in untreated and transplanted patients. Metachromatic leukodystrophy subtype was determined based on the (expected) age of symptom onset. Disease activity was assessed by measuring gross motor function deterioration and brain MRI. Longitudinal analyses with measurements up to 23 years after diagnosis were performed using linear mixed models. CSF and blood neurofilament light chain and glial fibrillary acidic protein levels in pediatric controls were negatively associated with age (all P &lt; 0.001). Blood neurofilament light chain level at diagnosis (median, interquartile range; picogram per milliliter) was significantly increased in both pre-symptomatic (14.7, 10.6–56.7) and symptomatic patients (136, 40.8–445) compared to controls (5.6, 4.5–7.1), and highest amongst patients with late-infantile (456, 201–854) or early-juvenile MLD (291.0, 104–445) and those ineligible for treatment based on best practice (291, 57.4–472). Glial fibrillary acidic protein level (median, interquartile range; picogram per milliliter) was only increased in symptomatic patients (591, 224–1150) compared to controls (119, 78.2–338) and not significantly associated with treatment eligibility (P = 0.093). Higher blood neurofilament light chain and glial fibrillary acidic protein levels at diagnosis were associated with rapid disease progression in late-infantile (P = 0.006 and P = 0.051, respectively) and early-juvenile patients (P = 0.048 and P = 0.039, respectively). Finally, blood neurofilament light chain and glial fibrillary acidic protein levels decreased during follow-up in untreated and transplanted patients but remained elevated compared with controls. Only neurofilament light chain levels were associated with MRI deterioration (P &lt; 0.001). This study indicates that both proteins may be considered as non-invasive biomarkers for clinical phenotype and disease stage at clinical assessment, and that neurofilament light chain might enable neurologists to make better informed treatment decisions. In addition, neurofilament light chain holds promise assessing treatment response. Importantly, both biomarkers require pediatric reference values, given that their levels first decrease before increasing with advancing age.