Objective. —Neurofibromatosis 1 and neurofibromatosis 2 are autosomal dominant genetic disorders in which affected individuals develop both benign and malignant tumors at an increased frequency. Since the original National Institutes of Health Consensus Development Conference in 1987, there has been significant progress toward a more complete understanding of the molecular bases for neurofibromatosis 1 and neurofibromatosis 2. Our objective was to determine the diagnostic criteria for neurofibromatosis 1 and neurofibromatosis 2, recommendations for the care of patients and their families at diagnosis and during routine follow-up, and the role of DNA diagnostic testing in the evaluation of these disorders. Data Sources. —Published reports from 1966 through 1996 obtained by MEDLINE search and studies presented at national and international meetings. Study Selection. —All studies were reviewed and analyzed by consensus from multiple authors. Data Extraction. —Peer-reviewed published data were critically evaluated by independent extraction by multiple authors. Data Synthesis. —The main results of the review were qualitative and were reviewed by neurofibromatosis clinical directors worldwide through an Internet Web site. Conclusions. —On the basis of the information presented in this review, we propose a comprehensive approach to the diagnosis and treatment of individuals with neurofibromatosis 1 and neurofibromatosis 2.

https://jamanetwork.com/journals/jama/articlepdf/417288/jama_278_1_042.pdf

The diagnostic evaluation and multidisciplinary management of neurofibromatosis 1 and neurofibromatosis 2.

Editor—Anderson-Fabry disease (AFD) is a sphingolipid storage disorder resulting from the deficiency of the lysosomal enzyme α-galactosidase. Unlike most other lysosomal diseases, the inheritance is X linked. Disease manifestations in female heterozygotes have been reported, but are considered to be rare and usually mild.1 Asymptomatic corneal dystrophy (cornea verticillata and posterior lenticular cataract) is present in about 70% and is useful for heterozygote detection. About 30% of women have minimal angiokeratomas and <10% have infrequent attacks of neuropathic pains.1 However, female heterozygotes with severe and early cerebrovascular disease, strokes, and renal failure have been documented, but these serious manifestations were estimated to occur in only 1%.1 Because this is an X linked disorder, these severe manifestations in females were explained by skewed X inactivation.2 

Case reports are open to selection bias and there are no reported data on the frequency and severity of AFD manifestations in a large cohort of carriers. Women are not usually evaluated in the clinic unless they present with serious AFD complications, but they do attend for genetic counselling when their son or male relative is diagnosed with the disease.

During regular reviews of AFD families in the genetic clinic, we have observed multiple and more frequent AFD manifestations in female carriers than expected. Owing to the lack of clinical data and present health care policy, we were unable to perform clinical investigations. Therefore, a large cohort study using an AFD specific questionnaire was performed to establish the mortality and the frequency of all AFD manifestations in obligate carrier females.

All known (n=80) obligate carrier females, who were over the age of 18 and had demographic data recorded in the AFD register, were asked to participate in this study. Sixty (75%) agreed and provided data; non-responders were reminded on one …

Anderson-Fabry disease: clinical manifestations and impact of disease in a cohort of 60 obligate carrier females

Historically, neurofibromatosis 1 (NF1) has been inextricably linked with neurofibromatosis 2 (NF2). Both are inherited autosomal-dominant neurocutaneous disorders that have high de novo mutation rates and carry a high risk of tumour formation. However, they are clinically and genetically distinct diseases and should be considered as seperate entities. NF1 is a common disease that mainly affects the skin and peripheral nervous system and causes characteristic bony dysplasia. By contrast, NF2 is a rare disorder with a relative paucity of skin manifestations and high-grade malignancy is unusual. Neurological symptoms are the predominant problem and the cardinal sign is bilateral vestibular schwannomas. In this Review, I discuss the pertinent diagnostic, clinical, and genetic symptoms of NF1 and NF2. I also examine the current views on the pathogenesis of these neurocutaneous disorders in the wake of advances in molecular genetics and the development of mouse models of disease.

Neurofibromatosis 1 and neurofibromatosis 2: a twenty first century perspective

Neurofibromatosis type 2 (NF2) is a tumour-prone disorder characterised by the development of multiple schwannomas and meningiomas. Prevalence (initially estimated at 1: 200,000) is around 1 in 60,000. Affected individuals inevitably develop schwannomas, typically affecting both vestibular nerves and leading to hearing loss and deafness. The majority of patients present with hearing loss, which is usually unilateral at onset and may be accompanied or preceded by tinnitus. Vestibular schwannomas may also cause dizziness or imbalance as a first symptom. Nausea, vomiting or true vertigo are rare symptoms, except in late-stage disease. The other main tumours are schwannomas of the other cranial, spinal and peripheral nerves; meningiomas both intracranial (including optic nerve meningiomas) and intraspinal, and some low-grade central nervous system malignancies (ependymomas). Ophthalmic features are also prominent and include reduced visual acuity and cataract. About 70% of NF2 patients have skin tumours (intracutaneous plaque-like lesions or more deep-seated subcutaneous nodular tumours). Neurofibromatosis type 2 is a dominantly inherited tumour predisposition syndrome caused by mutations in the NF2 gene on chromosome 22. More than 50% of patients represent new mutations and as many as one-third are mosaic for the underlying disease-causing mutation. Although truncating mutations (nonsense and frameshifts) are the most frequent germline event and cause the most severe disease, single and multiple exon deletions are common. A strategy for detection of the latter is vital for a sensitive analysis. Diagnosis is based on clinical and neuroimaging studies. Presymptomatic genetic testing is an integral part of the management of NF2 families. Prenatal diagnosis and pre-implantation genetic diagnosis is possible. The main differential diagnosis of NF2 is schwannomatosis. NF2 represents a difficult management problem with most patients facing substantial morbidity and reduced life expectancy. Surgery remains the focus of current management although watchful waiting with careful surveillance and occasionally radiation treatment have a role. Prognosis is adversely affected by early age at onset, a higher number of meningiomas and having a truncating mutation. In the future, the development of tailored drug therapies aimed at the genetic level are likely to provide huge improvements for this devastating condition.

/pdf/neurofibromatosis-type-2-nf2-a-clinical-and-molecular-review-2l9j0m60q2.pdf

Neurofibromatosis type 2 (NF2): a clinical and molecular review.

Objective:To determine the incidence of vestibular schwannoma (VS) in sporadic, neurofibromatosis type 2 (NF2) germ-line and mosaic form in a 10-year period.Study Design:Review of all incident cases of VS presenting to the four main neurosurgical centers for a population of 4.1 million from 1990 to

Incidence of Vestibular Schwannoma and Neurofibromatosis 2 in the North West of England over a 10-year Period: Higher Incidence than Previously Thought

The gene predisposing to neurofibromatosis type 2 (NF2) on human chromosome 22 has revealed a wide variety of different mutations in NF2 individuals. These patients display a marked variability in clinical presentation, ranging from very severe disease with numerous tumors at a young age to a relatively mild condition much later in life. To investigate whether this phenotypic heterogeneity is determined by the type of mutation in NF2, we have collected clinical information on 111 NF2 cases from 73 different families on whom we have performed mutation screening in this gene. Sixty-seven individuals (56.2%) from 41 of these kindreds revealed 36 different putative disease-causing mutations. These include 26 proposed protein-truncating alterations (frameshift deletions/insertions and nonsense mutations), 6 splice-site mutations, 2 missense mutations, 1 base substitution in the 3' UTR of the NF2 cDNA, and a single 3-bp in-frame insertion. Seventeen of these mutations are novel, whereas the remaining 19 have been described previously in other NF2 individuals or sporadic tumors. When individuals harboring protein-truncating mutations are compared with cases with single codon alterations, a significant correlation (P < .001) with clinical outcome is observed. Twenty-four of 28 patients with mutations that cause premature truncation of the NF2 protein, schwannomin, present with severe phenotypes. In contrast, all 16 cases from three families with mutations that affect only a single amino acid have mild NF2. These data provide conclusive evidence that a phenotype/genotype correlation exists for certain NF2 mutations.

R. Weksberg

Papers

Type of mutation in the neurofibromatosis type 2 gene (NF2) frequently determines severity of disease.