Biallelic NAA60 variants with impaired n-terminal acetylation capacity cause autosomal recessive primary familial brain calcifications

Primary familial brain calcification (PFBC) is characterized by calcium deposition in the brain, causing progressive movement disorders, psychiatric symptoms, and cognitive decline. PFBC is a heterogeneous disorder currently linked to variants in six different genes, but most patients remain genetically undiagnosed. Here, we identify biallelic NAA60 variants in ten individuals from seven families with autosomal recessive PFBC. The NAA60 variants lead to loss-of-function with lack of protein N-terminal (Nt)-acetylation activity. We show that the phosphate importer SLC20A2 is a substrate of NAA60 in vitro. In cells, loss of NAA60 caused reduced surface levels of SLC20A2 and a reduction in extracellular phosphate uptake. This study establishes NAA60 as a causal gene for PFBC, provides a possible biochemical explanation of its disease-causing mechanisms and underscores NAA60-mediated Nt-acetylation of transmembrane proteins as a fundamental process for healthy neurobiological functioning.

A Multicenter Study of Self-Limited Epilepsy With Centrotemporal Spikes: Effectiveness of Antiseizure Medication With Respect to Spike-Wave Index

BACKGROUND

There is no certain validated electroencephalographic (EEG) parameters for outcome prediction in children with self-limited epilepsy with centrotemporal spikes. To assess the effectiveness of antiseizure medication (ASM) for seizure outcome with respect to the spike-wave index (SWI) on serial EEG recordings.

METHODS

In this multicenter study, the study cohort consisted of 604 children with self-limited epilepsy with centrotemporal spikes. A data set of epilepsy centers follow-up between 2010 and 2022. The cohort was divided into 4 groups as those receiving 3 different monotherapy (carbamazepine [CBZ]/valproic acid [VPA]/levetiracetam [LEV]) and dual therapy. SWI analysis was performed with the percent of spikes in the 2-minute epoch in the 5th 6th minutes of the nonrapid eye movement sleep EEG record. The study group were also categorized according to seizure burden with seizure frequency (I) >2 seizures and (II) >5 seizures. Seizure outcome was evaluated based on the reduction in seizure frequency over 6-month periods: (1) 50% reduction and (2) seizure-free (complete response).

RESULTS

ASM monotherapy was achieved in 74.5% children with VPA, CBZ, and LEV with similar rates of 85.8%, 85.7%, and 77.9%. Dual therapy was need in the 25.5% of children with SeLECT. More dual therapy was administered in children aged below 5 years with a rate of 46.2%. Earlier seizure-free achievement time was seen in children with LEV monotherapy with more complete-response rate (86.7%) compared the VPA and CBZ.

CONCLUSIONS

We also determined that the children on dual therapy had more SWI clearance in the subsequent EEG recordings. The ROC curve analyses were performed to predict initial drug selection with using the SWI% might be used for the prediction of ASM type and drug selection in children.

Case Report of Two Siblings Diagnosed with Osteogenesis Imperfecta Type XV with a New Mutation in the WNT1 Gene and Review of the Literature

Introduction

Osteogenesis imperfecta (OI) is a heritable disorder characterized by bone fractures and low bone mass. Recently, mutations of the WNT1 gene have been reported to be causative in OI. The mutation in WNT1 causes autosomal-recessive OI due to its critical role in bone formation. WNT1 mutations cause varying degrees of clinical severity, ranging from moderate to progressively deforming forms. In addition to the OI phenotype, our cases also had extra-skeletal findings.

Case Presentation

We describe two siblings with multiple fractures and developmental delay. A novel homozygous frameshift WNT1 mutation was detected in this family, and we reviewed the literature for WNT1-related OI cases.

Discussion

We report a novel variant with a clinical diagnosis of severe OI, and this review will provide a comprehensive overview of previously published cases of OI type XV. With a better understanding of disorders associated with WNT1 mutations, therapies targeting Wnt1 signaling pathway may contribute therapeutic benefits.

Pyridoxine-dependent Epilepsy caused by a Novel homozygous mutation in PLPBP Gene

Seizures in newborn infants may be the first finding of hereditary metabolic diseases. Pyridoxine-dependent epilepsy (PDE) is a treatable disorder associated with defects in the one of ALDH7A1, PNPO, or PLPBP genes and it is uncommon but progresses with persistent seizures in the neonatal and infancy period. The seizures are generally resistant to traditional antiepileptic drugs and show a dramatic response to high-dose pyridoxine. In 2016, mutations were reported in PLPBP (previously known as PROSC) gene, which encodes pyridoxal phosphate homeostatic protein (PLPHP).When early-onset antiepileptic resistant seizures are not treated, clinical findings emerge including the development of encephalopathy, congenital microcephaly, and subsequent retardation of psychomotor development. The present case is a 33-month-old female infant with seizures starting from postnatal day 1, who did not respond to traditional anti-epileptic drugs but responded to pyridoxine treatment. In the genetic tests, homozygote c.695 C > T (p.Ala232Val) mutation was determined in the PLPBP gene, which has not been previously identified. Since a specific treatment was found, this case is reported with the aim of emphasizing the need to consider pyridoxine dependence, which is one of the vitamin-dependent metabolic encephalopathies, in the differential diagnosis of epilepsy patients.

Evaluation of developmental profiles of children with hydrocephalus

OBJECTIVE

The objective of this study was to compare the developmental characteristics of children with hydrocephalus with those of healthy children.

MATERIAL AND METHODS

A total of 109 children aged between 2 and 46 months were included in the study, 54 patients diagnosed with hydrocephalus and 55 healthy children were evaluated with demographic data forms and Denver Developmental Screening Test II.

RESULTS

The mean personal-social (p<0.001), fine motor-adaptive (p<0.001), language (p<0.001), and gross motor subscale scores were significantly lower in children with hydrocephalus than in the control group. Personal-social (p=0.002) and gross motor (p=0.029) subscale scores were significantly lower in children with obstructive hydrocephalus than communicating hydrocephalus. There was a significant negative correlation between language scores and ages of the children with hydrocephalus (r=-0.350, p=0.009). It was found that children with obstructive hydrocephalus carry a 6.7 folds higher risk of experiencing problems in terms of personal-social development compared to those with communicating hydrocephalus (p=0.011).

CONCLUSION

We found that patients with hydrocephalus were developmentally retarded compared to the healthy control subjects. Retardation was the most prominent in the obstructive group. Our results showed that neurodevelopmental follow-up should be carried-out regularly in pediatric patients with hydrocephalus, and early intervention should be started in necessary cases.

Developmental evaluation in children experiencing febrile convulsions

BACKGROUND

The objective of this study was to determine the effect of febrile convulsion (FC) on neuromotor development.

METHODS

Data of 325 patients, who were followed up at our outpatient clinic and diagnosed with FC between January 2012 and December 2018, were retrospectively evaluated. Of these patients, 203 underwent the Denver Developmental Screening Test II (DDST II) and were included in the study as the patient group and 100 healthy children as the control group.

RESULTS

Of the study group, 84 (41.4%) were girls and 119 (58.6%) were boys (B/G: 1.4). Of all patients, 163 (80.3%) were diagnosed with simple FC, 22 (10.8%) with complicated FC, and 18 (8.9%) with FC+. There was no significant relationship found between FC subtypes and gender, family history of FC, family history of epilepsy, iron (Fe) deficiency, and Fe deficiency anemia. DDST II subtest points were significantly lower in all developmental areas in the patient group when compared to the controls (p < 0.001), while suspected and abnormal test results were higher in all developmental areas in the patient group compared to the controls (p=0.01). It was also determined that the language points were lower as the age of first seizure increased (r=- 0.319, p < 0.01).

CONCLUSIONS

Although FC is known to usually having a good prognosis, the low DDST II test results measured in this study indicated that the FC may pose a developmental risk and patients with FC should be followed up in terms of developmental features. Because of the retrospective nature of the study, there was no `preconvulsion` developmental evaluation. This is a major limitation of our study.