Diagnostic difficulties and possibilities of NF1-like syndromes in childhood

Analysis of visual evoked potentials in patients with neurofibromatosis type 1: new concepts

Introduction

Neurofibromatosis type 1 (NF type 1) is an autosomal dominant disease with typical clinical manifestations, such as skin lesions, Lisch nodules, optic pathway gliomas, and neurofibromas, caused by the mutation of the NF1 gene. Visual evoked potentials (VEP) present a measure of the electrophysiological response of visual cortex to a visual stimulus. The role of VEP in the pathophysiology of NF type 1 is very complex and requires additional research.

The Aim

We examined the differences between NF type 1 patients with normal and altered VEP and analyzed the correlation between the prolongation of P100 latency and disease severity.

Materials and methods

Two groups were formed: a control group and a study group with NF type 1 patients. Based on the control group analysis, a threshold value for a normal VEP finding of 116 ms was obtained, and it was used to divide the study group into subgroups with normal and altered VEP. We proceeded with examining the differences in clinical manifestations of the disease between the subgroups, after which we checked if there is a correlation between the prolongation of the P100 latency and the severity of the clinical picture according to the Riccardi scale. Statistical analysis was performed using the Pearson chi-square test and the Spearman correlation test in the program SPSS 28.0, with levels of statistical significance p = 0.05 and p = 0.001.

Results

In the group with the abnormal VEP we found a statistically significant more frequent occurrence of optic tract glioma (p = 0.008), tumors (p = 0.032), epilepsy (p = 0.043), and cognitive disorders (p = 0.028), while the other clinical signs had an equal prevalence in both groups. A moderately strong correlation (r s = 0.665) was observed between the prolongation of P100 latency and the severity of the clinical picture.

Conclusion

Our results showed the important role of VEP in the description of clinical phenotypes of NF type 1. The authors of the study propose VEP to be included in the diagnostic algorithms designed for patients with NF type 1.

A Child Plexiform Neurofibroma of the Temple Region: A Case Report

Plexiform neurofibroma is a rare variant of neurofibromatosis type 1. Diagnosis is challenging due to the highly variable clinical presentation. Early diagnosis is essential for appropriate treatment and prevention of complications. This report describes a sporadic solitary plexiform neurofibroma in the temporal region of a seven-year-old girl. The growth of the mass began at birth and grew steadily over five years. Subsequently, the mass began to expand rapidly. The patient underwent complete surgical resection under general anesthesia. Histopathological examination revealed a plexiform neurofibroma. In conclusion, surgical excision is the gold standard for cases with symptomatic, visible, large superficial lesions.

Neurofibromatosis-Noonan syndrome and growth deficiency in an Iranian girl due to a pathogenic variant in NF1 gene

BACKGROUND

Mutations in NF1 gene could cause allelic disorders with clinical spectrum of Neurofibromatosis type 1 to Noonan syndrome. Here, a 7-year-old Iranian girl is described with Neurofibromatosis-Noonan syndrome due to a pathogenic variant in NF1 gene.

METHODS

Clinical evaluations were performed along with genetic testing using whole exome sequencing (WES). The variant analysis including pathogenicity prediction was also done using bioinformatics tools.

RESULTS

The chief compliant of the patient was short stature and lack of proper weight gain. Other symptoms were developmental delay, learning disability, inadequate speech skill, broad forehead, hypertelorism, and epicanthal folds, low set ears and webbed neck. A small deletion, c.4375-4377delGAA, was found in NF1 gene using WES. This variant was classified as pathogenic according to ACMG.

CONCLUSIONS

NF1 variants may show variable phenotypes among the patients; identifying such variants is helpful in therapeutic management of the disease. WES is considered as an appropriate test to diagnose Neurofibromatosis-Noonan syndrome.

Genetic Disorders with Predisposition to Paediatric Haematopoietic Malignancies—A Review

The view of paediatric cancer as a genetic disease arises as genetic research develops. Germline mutations in cancer predisposition genes have been identified in about 10% of children. Paediatric cancers are characterized by heterogeneity in the types of genetic alterations that drive tumourigenesis. Interactions between germline and somatic mutations are a key determinant of cancer development. In 40% of patients, the family history does not predict the presence of inherited cancer predisposition syndromes and many cases go undetected. Paediatricians should be aware of specific symptoms, which highlight the need of evaluation for cancer syndromes. The quickest possible identification of such syndromes is of key importance, due to the possibility of early detection of neoplasms, followed by presymptomatic genetic testing of relatives, implementation of appropriate clinical procedures (e.g., avoiding radiotherapy), prophylactic surgical resection of organs at risk, or searching for donors of hematopoietic stem cells. Targetable driver mutations and corresponding signalling pathways provide a novel precision medicine strategy.Therefore, there is a need for multi-disciplinary cooperation between a paediatrician, an oncologist, a geneticist, and a psychologist during the surveillance of families with an increased cancer risk. This review aimed to emphasize the role of cancer-predisposition gene diagnostics in the genetic surveillance and medical care in paediatric oncology.

Early Developmental Trajectories in Infants With Neurofibromatosis 1

Objective

To examine the trajectories of cognitive, motor and behavioural development in infants with NF1 compared to infants without a family history of neurodevelopmental difficulties.

Study design

Infants with NF1 and low-risk controls were recruited from 5 months of age and followed longitudinally. Data from standardised tests was gathered at 5, 10 and 14 months and developmental trajectories of motor, language, behaviour, sleep, social development and parent-infant interaction were examined. Linear mixed modelling was used to estimate group differences in cognitive and behavioural measures over time.

Results

No group differences were observed on Mullen Scale of Early Learning, overall adaptive functioning, temperament or behavioural measures. There were no group differences observed on measures of social communication or parent-infant interaction. Over the course of development, the NF1 group slept less and took more time to settle to sleep as compared to the control group. Maternal education was significantly associated with cognitive and behavioural developmental outcomes in both groups.

Conclusion

Cognitive, social and behavioural impairments are a cause of significant functional morbidity in children with NF1. This report is the first study to investigate the trajectories of cognitive, motor and behavioural development in infancy in NF1. Our results demonstrate that overall cognitive and behavioural developmental trajectories of the NF1 group in the infancy period are similar to controls. Given previous reports of delayed development in the NF1 cohort by 40 months, early clinical interventions strategies to promote sleep hygiene may be beneficial to optimise developmental outcomes.

LZTR1 molecular genetic overlap with clinical implications for Noonan syndrome and schwannomatosis

Background

Noonan syndrome (NS) is a genetic disorder characterized by developmental delays, typical facial gestalt and cardiovascular defects. LZTR1 variants have been recently described in patients with NS and schwannomatosis, but the association, inheritance pattern and management strategy has not been fully elucidated. Here, we review the contribution of LZTR1 in NS and describe a patient with a novel, likely pathogenic variant in LZTR1.

Case presentation

A female patient was diagnosed with clinical NS at 8 months of age. She presented in adulthood when a brain and spine MRI identified plexiform neurofibromas; however, she did not meet the clinical criteria for Neurofibromatosis type 1. No pathogenic variants were identified through molecular genetic analysis of NF1, SPRED1 and a multigene NS panel. Whole exome sequencing at age 23 identified a novel de novo likely pathogenic heterozygous variant in the LZTR1 gene denoted as c.743G>A (p.Gly248Glu). Serial MRIs have shown stable imaging findings and the patient is being followed clinically by cardiology, neurology and medical genetics.

Conclusions

We identified a novel mutation in the LZTR1 gene, not previously reported in association with NS. This report provides additional evidence to support for the assessment of schwannomatosis in patients with LZTR1-NS and may have overlap with Neurofibromatosis type 1.