Type 1 neurofibromatosis and the pediatric patient

Precocious puberty in children with neurofibromatosis type 1

We undertook a comprehensive study of children with neurofibromatosis type 1 (NF-1) cared for in a large multidisciplinary clinic to determine the prevalence of precocious puberty and its relationship to optic pathway tumors (OPTs). Precocious puberty was diagnosed in 7 of 219 children with NF-1 (5 boys and 2 girls) examined between Jan. 1, 1985, and April 20, 1993. All seven children had OPTs involving the optic chiasm; they represented 39% of children with NF-1 and chiasmal tumors (95% confidence interval, 17% to 64%). Eleven prepubertal children (aged 2 to 10 years) with NF-1 and OPTs, and age- and sex-matched NF-1 control subjects without OPTs, underwent luteinizing hormone-releasing hormone (LH-RH) stimulation tests. Two boys with OPTs had pubertal luteinizing hormone (LH) responses, and testosterone levels > 10 ng/dl. Basal LH levels were also elevated in these two boys when tested with a very sensitive immunochemiluminometric assay. None of the children without an OPT had either a pubertal response to LH-RH or an elevated basal LH level. We conclude that precocious puberty in children with NF-1 is found exclusively in those who have OPTs involving the optic chiasm; it is a common complication in those children. With the use of a highly sensitive LH assay, biochemical evidence of hypothalamic-pituitary-gonadal axis activation may be demonstrated, even without provocative testing.

Infantile spasms in patients with neurofibromatosis type 1

The authors report two patients with neurofibromatosis type 1 who were affected by infantile spasms. The infantile spasms were severe and unresponsive to anticonvulsant treatment. The authors maintain that infantile spasms may belong to the clinical features of neurofibromatosis type 1.

Optic gliomas in neurofibromatosis type 1: role of visual evoked potentials

Optic gliomas occur in 15% of patients with neurofibromatosis type 1 (NF 1) and are a significant cause of morbidity. Of these tumors, 20-30% become symptomatic, usually before age 10 years. Previous studies have suggested that visual evoked potentials (VEPs) are a sensitive method for the detection of asymptomatic optic gliomas. Because routine neuroimaging of children with NF 1 is currently not recommended, the role of pattern-shift VEPs (PS VEPs) as a screening test for optic gliomas was evaluated. PS VEPs were performed on 10 children with NF 1 and optic gliomas and 20 children with NF 1 and normal visual pathways (as defined on MRI). PS VEPs had 90% sensitivity for detecting optic gliomas, with an increase in sensitivity to 100% when hemifield stimulation was used. The specificity of the test was 60%. Four of 20 children without optic gliomas had thickened optic nerves on computed tomography which represented dural ectasia with normal visual pathways on MRI; PS VEPs were normal in these patients. The efficacy of PS VEPs as a routine screen for optic gliomas is limited by the age at which children will cooperate with the test procedure and the high incidence of false-positive results; however, VEPs do provide a useful adjunct to routine clinical ophthalmologic assessment in the detection of optic gliomas in children with NF 1. Abnormal test results provide a stronger indication for neuroimaging. The early detection of optic gliomas allows for close monitoring of tumor progression and earlier intervention prior to significant visual loss.

Neurofibromatosis presenting as a severe systemic vasculopathy

In a boy with neurofibromatosis type 1 (NF-1), hypertension, septic infection of an aneurysm in the deltoid muscle, bowel infarction, multiple arterial aneurysms and venous thrombosis occurred within a period of 6 weeks. Histologically, vascular neurofibromatosis of the small vessels of the gut was found. This unusual occurrence of a multitude of clinical features within a few weeks was caused by vascular neurofibromatosis. Awareness of this condition in patients with NF-1 may help the paediatrician to avoid unnecessary diagnostic procedures and to initiate appropriate symptomatic therapy.

Clinical and genetic patterns of neurofibromatosis 1 and 2

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Neurofibromatosis type 1: review of the first 200 patients in an Australian clinic

Neurofibromatosis type 1 is a common multisystem disorder, best managed in a multidisciplinary clinic. In 1991, the first Australian neurofibromatosis clinic was established at the Children's Hospital, Camperdown, and the clinical characteristics of the first 150 families are reviewed. Two hundred individuals were assessed; there was an equal sex distribution, and 55% of cases were sporadic. Advanced paternal age appeared to predispose to new mutations in the neurofibromatosis gene. Café-au-lait spots and axillary freckling were important to the diagnosis of neurofibromatosis type 1 during childhood, and neurofibromas and Lisch nodules, although often not appearing until after puberty, were present in almost all patients over 30 years of age. Short stature (27%), macrocephaly (43%), scoliosis (20.5%), and learning disabilities (45%) were common associated features. The prevalence of disease complications was similar to the major US and European studies.

A genetic study of neurofibromatosis type 1 (NF1) in south-western Ontario. II. A PCR based approach to molecular and prenatal diagnosis using linkage

Neurofibromatosis type 1 (NF1) is a common, autosomal dominant genetic disorder with a variety of highly variable symptoms including cutaneous manifestations (such as café au lait spots), Lisch nodules, plexiform neurofibromas, skeletal abnormalities, an increased risk for malignancy, and the development of learning disabilities. The wide clinical variability of expression of the disease phenotype and high (spontaneous) mutation rate of the NF1 gene indicate that careful clinical examination of patients and family members is necessary to provide an accurate diagnosis of the disease. Since very few NF1 mutations have been identified, and with the apparent lack of a predominant mutation in this large, highly mutable gene, molecular diagnosis of NF1 will continue to be based on haplotypes using linkage analysis. Here we report our experiences while providing a molecular diagnostic service for NF1 in the ethnically diverse region of south-western Ontario. Molecular diagnoses with at least one informative probe/enzyme combination are reported for 19 families including two families requesting prenatal diagnosis for NF1. We have augmented the classical Southern based approach to linkage analysis with the use of PCR based assays for molecular linkage. Furthermore, criteria have been established in our laboratory for executing molecular linkage based on heterozygosity values, recombination fractions, and the use of intragenic probes/markers.