Clinical aspects of neurofibromatosis 1

Cognitive features that distinguish preschool-age children with neurofibromatosis type 1 from their peers: a matched case-control study

OBJECTIVE

To examine the cognitive functioning of 40-month-old children with neurofibromatosis type 1 (NF1).

STUDY DESIGN

In this case-control study, 43 children with NF1 and 43 comparison children (matched by age, sex, and maternal years of education) were assessed using the Wechsler Preschool and Primary Scale of Intelligence, Third Edition. Language, visual perception, preliteracy, and executive functioning were also examined. Parents completed questionnaires about their child's behavior. Group differences were examined using the paired-samples t test or the related Wilcoxon signed rank test. Conditional logistic regression was conducted to identify which cognitive variables predicted group membership (ie, NF1 or control).

RESULTS

The NF1 group had significantly poorer general intelligence than matched comparisons. Preschool-age children with NF1 had significantly poorer language, visual perception, response inhibition, and preliteracy skills than comparison children. The Wechsler Preschool and Primary Scale of Intelligence, Third Edition, Object Assembly and Information subtests were significant predictors of group membership. Parent ratings indicated no group differences in behavior.

CONCLUSIONS

After accounting for potentially confounding variables of age, sex, and maternal years of education, young children with NF1 have significantly poorer intellectual functioning, expressive language, and visual perception. These cognitive features that distinguish young children with NF1 from healthy peers can be detected in the preschool age group and are likely to impact on learning and performance during early school years. These areas should be targeted for intervention to maximize the developmental outcomes of young children with NF1.

Intra-abdominal plexiform neurofibromatosis including periportal, mesentery, and gastrointestinal tract involvement in neurofibromatosis type 1: case report and review of the literature

We report a case of intra-abdominal plexiform neurofibromatosis, including periportal, mesenteric, and gastrointestinal tract involvement, in a patient with von Recklinghausen's disease/neurofibromatosis type 1 (NF-1). A 26-year-old man with familial NF-1 was admitted to hospital for further examination of an abnormal hepatic mass along the portal vein. Esophagogastroduodenoscopy revealed antral wall thickening and swelling of the papilla of Vater. Mucosal biopsies taken from the duodenum revealed possible ganglioneuromatosis. Abdominal ultrasonography, contrast-enhanced computed tomography, and magnetic resonance imaging revealed an abnormal periportal mass with serpiginous extension into the liver along the portal vein and the mesentery, which is the typical spread pattern of plexiform neurofibromatosis. A laparotomy and cholecystectomy for gallstones were performed, and this patient was diagnosed as having intra-abdominal plexiform neurofibromatosis. This is the 15th case of intrahepatic periportal plexiform neurofibromatosis and the 16th case of diffuse ganglioneuromatosis associated with NF-1 in the English literature. The imaging findings of the lesion have been followed for 10 years; there has been slight growth of the mass, but no malignant transformation has been found. The previously reported cases are reviewed.

The neurofibromin GAP-related domain rescues endothelial but not neural crest development in Nf1 mice

Neurofibromatosis type I (NF1; also known as von Recklinghausen's disease) is a common autosomal-dominant condition primarily affecting neural crest-derived tissues. The disease gene, NF1, encodes neurofibromin, a protein of over 2,800 amino acids that contains a 216-amino acid domain with Ras-GTPase-activating protein (Ras-GAP) activity. Potential therapies for NF1 currently in development and being tested in clinical trials are designed to modify NF1 Ras-GAP activity or target downstream effectors of Ras signaling. Mice lacking the murine homolog (Nf1) have mid-gestation lethal cardiovascular defects due to a requirement for neurofibromin in embryonic endothelium. We sought to determine whether the GAP activity of neurofibromin is sufficient to rescue complete loss of function or whether other as yet unidentified functions of neurofibromin might also exist. Using cre-inducible ubiquitous and tissue-specific expression, we demonstrate that the isolated GAP-related domain (GRD) rescued cardiovascular development in Nf1(-/-) embryos, but overgrowth of neural crest-derived tissues persisted, leading to perinatal lethality. These results suggest that neurofibromin may possess activities outside of the GRD that modulate neural crest homeostasis and that therapeutic approaches solely aimed at targeting Ras activity may not be sufficient to treat tumors of neural crest origin in NF1.

Serum IgE levels in neurofibromatosis 1

A descriptive case study was performed on 75 patients with NF1 (neurofibromatosis type 1) from the CNNF (Brazil) database. Serum IgE levels were determined using the IgE radioimmunosorbent test, with the reference values of 75-502 IU mL(-1). The patients were divided into groups, with 25 patients presenting plexiform neurofibromas, 25 presenting neurofibromas and 25 presenting no neurofibromas. The purposes of this study were to determine the serum IgE levels of patients with NF1 presenting plexiform neurofibromas, neurofibromas and no neurofibromas, as well as to determine possible correlations between serum IgE levels and the size of the plexiform neurofibromas and neurofibromas presented by these patients. Elevated serum IgE levels were observed in all the patient groups. We did not observe a correlation between IgE levels and age in these patients; however, we did observe correlations between IgE levels and neurofibroma and plexiform neurofibroma size. We suggest further studies to confirm these results and to investigate in greater depth the possible role of IgE in the development and growth of neurofibromas and plexiform neurofibromas in NF1.

Neurocutaneous syndromes and epilepsy-issues in diagnosis and management

Epilepsy may be seen as a feature of many of the neurocutaneous syndromes. The challenge lies within the diagnosis of the specific disorder and ultimately control of the epilepsy. Tuberous sclerosis is the most common of the disorders with a frequency of 4.9/100,000. An autosomal-dominant condition, diagnostic features may be unclear under 2 years of age. Population studies suggest a prevalence of epilepsy of 78%, the majority presenting under the age of 12 months, with a high association between the occurrence of seizures and the presence of learning disability. Although an apparent multifocal disease, surgery may have a role to play where seizures are demonstrated to probably arise from a single tuber. Other less common neurocutaneous syndromes also have a high prevalence of epilepsy in association with cerebral malformations; unilateral or lobar malformations should be referred early for surgical consideration. Neurofibromatosis is the second most common of the disorders but the prevalence of epilepsy in this population is relatively low; in addition, a greater proportion may be easier to treat with medication.

Neurocutaneous syndromes: behavioral features

Neurocutaneous syndromes are disorders characterized by a neurological abnormality and cutaneous manifestations. Three of the more common neurocutaneous syndromes are Sturge-Weber syndrome, tuberous sclerosis, and neurofibromatosis. This review focuses on the cognitive and behavioral features of these syndromes.

Neurofibromatosis 1: clinical review and exceptions to the rules

Neurofibromatosis 1 is an autosomal dominant, multisystem disorder with myriad clinical manifestations. Between 1991 and 1998, 495 adults and children were diagnosed with neurofibromatosis 1 at a specialized neurogenetics clinic in Sydney, Australia. This review establishes the prevalence of the clinical manifestations of neurofibromatosis 1 in these patients and provides guidelines for assessment and management. In addition, we review in detail patients who had unusual presentations and who represent important "exceptions to the rules" of clinical practice.