Four-year follow-up study in a NF1 boy with a focal pontine hamartoma

Accurate Classification of NF1 Gene Variants in 84 Italian Patients with Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) is one of the most common autosomal dominant genetic diseases. It is caused by mutations in the NF1 gene encoding for the large protein, neurofibromin. Genetic testing of NF1 is cumbersome because 50% of cases are sporadic, and there are no mutation hot spots. In addition, the most recognizable NF1 clinical features—café-au-lait (CALs) spots and axillary and/or inguinal freckling—appear early in childhood but are rather non-specific. Thus, the identification of causative variants is extremely important for early diagnosis, especially in paediatric patients. Here, we aimed to identify the underlying genetic defects in 72 index patients referred to our centre for NF1. Causative mutations were identified in 58 subjects, with 29 being novel changes. We evaluated missense and non-canonical splicing mutations with both protein and splicing prediction algorithms. The ratio of splicing mutations detected was higher than that reported in recent patients’ series and in the Human Gene Mutation Database (HGMD). After applying in silico predictive tools to 41 previously reported missense variants, we demonstrated that 46.3% of these putatively missense mutations were forecasted to alter splicing instead. Our data suggest that mutations affecting splicing can be frequently underscored if not analysed in depth. We confirm that hamartomas can be useful for diagnosing NF1 in children. Lisch nodules and cutaneous neurofibromas were more frequent in patients with frameshifting mutations. In conclusion, we demonstrated that comprehensive in silico analysis can be a highly specific method for predicting the nature of NF1 mutations and may help in assuring proper patient care.

Long-term survival of an infant with diffuse brainstem lesion diagnosed by prenatal MRI: a case report and review of the literature

BACKGROUND

We describe a unique case of expansive diffuse brainstem lesion diagnosed prenatally by magnetic resonance imaging (MRI) with long-term survival. Findings of fetal and postpartum MRI were highly consistent with the characteristics of diffuse brainstem glioma.

METHODS

Diagnosis was based on the features of MRI, and histopathology was not confirmed by biopsy. Although the prognosis of diffuse brainstem tumor is usually poor, this child was asymptomatic at birth and the neurological condition is still normal at 4 years of age without any treatment.

RESULTS

During routine imaging follow-up, diameters of the expansion have remained stable, while the size of the lesion compared to the posterior fossa size has diminished. In addition to brainstem tumor, a skin lesion of the back was observed and MRI of the thoracic spine showed a large asymptomatic extradural cystic lesion suggesting an arachnoid cyst. The pontine tumor of this infant, in agreement with a few previously reported cases, suggests a subgroup of beneficial outcome of expansive diffuse brainstem lesions, particularly in the neonatal period.

DISCUSSION

In this article, we discuss the prognosis and characteristics of pediatric brainstem tumors and differential diagnosis of neonatal brainstem lesions.

Neurofibromatosis type 1 and attention deficit hyperactivity disorder: a case study and literature review

BACKGROUND

The cognitive profile of children with neurofibromatosis type 1 (NF1) and attention deficit hyperactivity disorder (ADHD) has been well characterized, but few studies have evaluated the cognitive abilities of adults with NF1 and ADHD.

OBJECTIVES

We investigated 1) the cognitive profile of an adult patient with NF1 and inattention problems, 2) changes in his cognition after 14 months of follow-up, and 3) whether the patient exhibited comorbid NF1 and ADHD or secondary ADHD-like symptoms.

METHODS

We administered neuropsychological tests of executive function, attention, verbal and visual memory, visuospatial function, and language during two evaluations separated by 14 months.

RESULTS

We found no changes in sustained attention, language, or verbal memory. Visual memory, verbal learning, selective attention inhibitory control, and problem solving declined over time, whereas visual search, psychomotor speed, visuospatial function, and mental flexibility improved.

CONCLUSION

Our patient exhibited a cognitive profile characteristic of both NF1 and ADHD, leading to the hypothesis that the patient had comorbid ADHD instead of secondary ADHD-like symptoms. More studies are necessary to characterize the cognition of patients with NF1 and ADHD.