Familial café au lait spots: a variant of neurofibromatosis type 1

Single Stage Nasal Reconstruction for Solitary Neurofibroma Isolated in the Columella

Neurofibromas are benign peripheral nerve sheath tumors that can originate from several elements of peripheral nerves, including axons, Schwann cells, endoneurial fibroblasts, and perineurial cells. The occurrence of a solitary neurofibroma in the external nose, especially that isolated in the nasal columella, is extremely rare. To the best of our knowledge, only 4 cases of solitary neurofibromas in the external nose have been reported in the English literature: on the nasal dorsum, tip, and pyriform aperture, all originating from the trigeminal nerve. We report the first case of a solitary neurofibroma isolated in the nasal columella, which we found in an otherwise healthy 42-year-old man. We completely resected this tumor with a negative resection margin and performed reconstruction with a bilateral spreader graft and caudal septal extension graft using autologous septal cartilage. The postoperative course was successful in both cosmetic and functional results, with no sensory changes at the 1-year follow-up. Surgical treatment for this lesion was challenging due to the cosmetically obvious location and high rate of recurrence. A review of the literature highlights the clinical and histological characteristics, differential diagnosis, and management of solitary neurofibroma of the external nose.

Updated Approach to Patients with Multiple Café au Lait Macules

Café au lait macules (CALMs) are a normal and frequent finding in the general population, but multiple CALMs raise the possibility of an underlying neurocutaneous disease like neurofibromatosis type I. Certain features of CALMs like number, size, shape, and distribution are important in identifying children at higher risk of having a neurocutaneous disorder or another genetic disorder. Genetic testing can be especially helpful in establishing a diagnosis in atypical presentations, or when the child is young and other features of the disease aside from CALMs have not manifested.

Neurofibromatosis Type 1 in Children: A Single-Center Experience

OBJECTIVE

Neurofibromatosis (NF) is the most common autosomal dominantly inherited neurocutaneous syndrome. The characteristic features of NF type 1 (NF-1) are café au lait spots, axillary and inguinal freckling, peripheral neurofibromas, optic pathway glioma, and Lisch nodules. The present study aimed to analyze the clinical features of children with NF-1.

MATERIALS AND METHODS

In this study, the children with NF-1 diagnosed and followed-up in our center between 2000 and 2020 were retrospectively evaluated. Demographic and clinical features of patients were defined.

RESULTS

The study group consisted of 52 patients. Of those, 25 were boys and 27 were girls. The children's median age at diagnosis was 5.9 years (1-15.8). Café au lait (CAL) spots and axillary/inguinal freckling were observed in 50 and 24 patients, respectively. Neurofibroma was present in 22 cases. Ten of the cohort had optic gliomas, and 39 of them had cranial hamartomas. Orthopedic complications such as scoliosis, tibial pseudoarthrosis, and osteoporosis were observed in 13 patients. Eleven children had neurocognitive disorders.

CONCLUSIONS

Early diagnosis is important in neurofibromatosis to prevent the complications of the disease. Also, neurological development and secondary malignancy follow-up should be done carefully in this group of patients.

Café au lait spots: When and how to pursue their genetic origins

Café au lait spots are common birthmarks seen sporadically and in association with several genetic syndromes. Dermatologists are often asked to evaluate these birthmarks both by other physicians and by parents. In some cases, it is challenging to know when and how to pursue further evaluation. Diagnostic challenges may come in the form of the appearance of the individual lesions, areas and patterns of cutaneous involvement, and associated features (or lack thereof). In this review, we aim to clarify when and how to evaluate the child with multiple or patterned café au lait spots and to explain some emerging concepts in our understanding of the genetics of these lesions.

Treatment of Café-Au-Lait Spots Using Q-Switched Alexandrite Laser: Analysis of Clinical Characteristics of 471 Children in Mainland China

Background and Objectives

Café‐au‐lait spots, also known as café‐au‐lait macules (CALMs), are a common pigmentary disorder. Although various laser modalities have been used to treat CALMs, the efficacy of laser treatment in children differs from that in adults. We investigated the efficacy, safety, and clinical factors of the treatment of CALMs using Q‐switched alexandrite laser (755 nm) therapy in children.

Methods

In total, 471 children with CALMs underwent Q‐switched alexandrite laser therapy at a treatment interval of 3–12 months. The safety and efficacy of the laser treatment were evaluated by reviewing clinical records and photographs before and after treatments.

Results

Of the 471 patients, 140 (29.72%) were cured completely, 124 (26.33%) showed substantial improvement, 110 (23.35%) showed improvement, and 97 (20.60%) showed no improvement after one to nine treatments. The overall treatment success rate was 79.41%, and the treatment efficacy was positively correlated with the number of laser treatments (rs = 0.26, P < 0.0001). Sex and the interval of laser treatments were also associated with significant differences in treatment outcomes (P < 0.05). No obvious adverse effects were observed. Multivariate logistic regression analysis showed that the number of treatments influenced the treatment efficacy (odds ratio, 2.130; 95% confidence interval, 1.561–2.908).

Conclusions

Q‐switched alexandrite laser (755 nm) therapy is safe and highly effective for CALMs in children, and the number of treatments affects the treatment efficacy. Lasers Surg. Med. © 2019 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.

Multiple Café au Lait Spots in a Group of Fair-Skinned Children without Signs or Symptoms of Neurofibromatosis Type 1

BACKGROUND

The presence of six or more café au lait (CAL) spots is a criterion for the diagnosis of neurofibromatosis type 1 (NF-1). Children with multiple CAL spots are often referred to dermatologists for NF-1 screening. The objective of this case series is to characterize a subset of fair-complected children with red or blond hair and multiple feathery CAL spots who did not meet the criteria for NF-1 at the time of their last evaluation.

METHODS

We conducted a chart review of eight patients seen in our pediatric dermatology clinic who were previously identified as having multiple CAL spots and no other signs or symptoms of NF-1.

RESULTS

We describe eight patients ages 2 to 9 years old with multiple, irregular CAL spots with feathery borders and no other signs or symptoms of NF-1. Most of these patients had red or blond hair and were fair complected. All patients were evaluated in our pediatric dermatology clinic, some with a geneticist. The number of CAL spots per patient ranged from 5 to 15 (mean 9.4, median 9).

CONCLUSION

A subset of children, many with fair complexions and red or blond hair, has an increased number of feathery CAL spots and appears unlikely to develop NF-1, although genetic testing was not conducted. It is important to recognize the benign nature of CAL spots in these patients so that appropriate screening and follow-up recommendations may be made.

p.Arg1809Cys substitution in neurofibromin is associated with a distinctive NF1 phenotype without neurofibromas

Analysis of 786 NF1 mutation-positive subjects with clinical diagnosis of neurofibromatosis type 1 (NF1) allowed to identify the heterozygous c.5425C>T missense variant (p.Arg1809Cys) in six (0.7%) unrelated probands (three familial and three sporadic cases), all exhibiting a mild form of disease. Detailed clinical characterization of these subjects and other eight affected relatives showed that all individuals had multiple cafè-au-lait spots, frequently associated with skinfold freckling, but absence of discrete cutaneous or plexiform neurofibromas, Lisch nodules, typical NF1 osseous lesions or symptomatic optic gliomas. Facial features in half of the individuals were suggestive of Noonan syndrome. Our finding and revision of the literature consistently indicate that the c.5425C>T change is associated with a distinctive, mild form of NF1, providing new data with direct impact on genetic counseling and patient management.

The diagnostic and clinical significance of café-au-lait macules

Café-au-lait, also referred to as café-au-lait spots or café-au-lait macules, present as well-circumscribed, evenly pigmented macules and patches that range in size from 1 to 2 mm to greater than 20 cm in greatest diameter. Café-au-lait are common in children. Although most café-au-lait present as 1 or 2 spots in an otherwise healthy child, the presence of multiple café-au-lait, large segmental café-au-lait, associated facial dysmorphism, other cutaneous anomalies, or unusual findings on physical examination should suggest the possibility of an associated syndrome. While neurofibromatosis type 1 is the most common syndrome seen in children with multiple café-au-lait, other syndromes associated with one or more café-au-lait include McCune-Albright syndrome, Legius syndrome, Noonan syndrome and other neuro-cardio-facialcutaneous syndromes, ring chromosome syndromes, and constitutional mismatch repair deficiency syndrome.

SPRED 1 mutations in a neurofibromatosis clinic

Legius syndrome, caused by SPRED1 mutations, has phenotypic overlap with neurofibromatosis type 1 (NF1) without tumorigenic manifestations. Patients fulfilling the National Institutes of Health (NIH) diagnostic criteria for NF1 were enrolled at the University of Utah NF Clinic, and SPRED1 mutation analysis was performed to identify the frequency of Legius syndrome within an NF1 clinic population. SPRED1 sequencing was performed on 151 individuals with the clinical diagnosis of NF1, and 2 individuals (1.3%) were found to have novel SPRED1 mutations, p.R18X and p.Q194X. The phenotypes for the 2 individuals with SPRED1 mutations included altered pigmentation without tumorigenesis. A specific SPRED1 haplotype allele was identified in 27 individuals. The frequency of SPRED1 mutations in patients meeting diagnostic criteria for NF1 in a hospital-based clinic is 1% to 2%. The likelihood an individual is harboring a SPRED1 mutation increases with age if multiple, nonpigmentary NF1 findings are absent. Legius syndrome patients may benefit from altered medical surveillance.

Neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is an autosomal dominant, multisystem disorder affecting approximately 1 in 3500 people. Significant advances in the understanding of the pathophysiology of NF1 have been made in the last decade. While no medical therapies for NF1 are currently available, trials are ongoing to discover and test medical treatments for the various manifestations of NF1, primarily plexiform neurofibromas, learning disabilities, and optic pathway gliomas. In addition, mutational analysis has become available on a clinical basis and is useful for diagnostic confirmation in individuals who do not fulfill diagnostic criteria or when a prenatal diagnosis is desired. There are several disorders that may share overlapping features with NF1; in 2007, a disorder with cutaneous findings similar to NF1 was described. This paper addresses the dermatologist's role in diagnosis and management of NF1 and describes the variety of cutaneous and extracutaneous findings in NF1 to which the dermatologist may be exposed.

LEARNING OBJECTIVES

After completing this learning activity, participants should be able to discuss the indications and limitations of genetic testing in neurofibromatosis type 1, distinguish common and uncommon cutaneous findings, and recognize the dermatologist's role in diagnosis and management.

A severe form of Noonan syndrome and autosomal dominant café-au-lait spots - evidence for different genetic origins

AIM

The clinical overlap among Noonan syndrome (NS), cardio-facio-cutaneous (CFC), LEOPARD and Costello syndromes as well as Neurofibromatosis type 1 is extensive, which complicates the process of diagnosis. Further genotype-phenotype correlations are required to facilitate future diagnosis of these patients. Therefore, investigations of the genetic cause of a severe phenotype in a patient with NS and the presence of multiple café-au-lait spots (CAL) spots in the patient and four members of the family were performed.

METHODS

Mutation analyses of candidate genes, PTPN11, NF1, SPRED1 and SPRED2, associated with these syndromes, were conducted using DNA sequencing.

RESULTS

A previously identified de novo mutation, PTPN11 F285L and an inherited NF1 R1809C substitution in the index patient were found. However, neither PTPN11 F285L, NF1 R1809C, SPRED1 nor SPRED2 segregated with CAL spots in the family. The results indicate that the familial CAL spots trait in this family is caused by a mutation in another gene, distinct from previous genes associated with CAL spots in these syndromes.

CONCLUSION

We suggest that the atypical severe symptoms in the index patient may be caused by an additive effect on the F285L mutation in PTPN11 by another mutation, for example the NF1 R1809C or alternatively, the not yet identified gene mutation associated with CAL spots in this family.

Hypermelanoses of the Newborn and of the Infant

This article discusses hypermelanoses present at birth or appearing in the first months of life. They may be transient or permanent, localized - as in café-au-lait spots - or segmental, or more rarely, complex or generalized. In most pigmentary diseases, physical examination, including Wood's lamp examination and a detailed history, is usually sufficient. Time of onset, distribution pattern, and associated clinical and sometimes histopathologic findings are helpful in differentiating these disorders. Recently, molecular diagnosis has become available for some rare entities, such as hereditary symmetrical dyschromatoses, but the bulk of nevoid lesions are not understood at the molecular level.

An absence of cutaneous neurofibromas associated with a 3-bp inframe deletion in exon 17 of the NF1 gene (c.2970-2972 delAAT): evidence of a clinically significant NF1 genotype-phenotype correlation

Neurofibromatosis type 1 (NF1) is characterized by cafe-au-lait spots, skinfold freckling, and cutaneous neurofibromas. No obvious relationships between small mutations (<20 bp) of the NF1 gene and a specific phenotype have previously been demonstrated, which suggests that interaction with either unlinked modifying genes and/or the normal NF1 allele may be involved in the development of the particular clinical features associated with NF1. We identified 21 unrelated probands with NF1 (14 familial and 7 sporadic cases) who were all found to have the same c.2970-2972 delAAT (p.990delM) mutation but no cutaneous neurofibromas or clinically obvious plexiform neurofibromas. Molecular analysis identified the same 3-bp inframe deletion (c.2970-2972 delAAT) in exon 17 of the NF1 gene in all affected subjects. The Delta AAT mutation is predicted to result in the loss of one of two adjacent methionines (codon 991 or 992) ( Delta Met991), in conjunction with silent ACA-->ACG change of codon 990. These two methionine residues are located in a highly conserved region of neurofibromin and are expected, therefore, to have a functional role in the protein. Our data represent results from the first study to correlate a specific small mutation of the NF1 gene to the expression of a particular clinical phenotype. The biological mechanism that relates this specific mutation to the suppression of cutaneous neurofibroma development is unknown.

La neurofibromatose 1 (NF1) ou maladie de Von Recklinghausen

OBJECTIVES

Neurofibromatosis 1(NF1) is one of the most common genetic diseases. NF1 is an autosomal dominant genetic disorder and half of affected individuals have NF1 as the result of a new gene NF1 mutation. The offspring of an affected individual have a 50% risk of inheriting the altered NF1 gene. The disease manifestations are extremely variable, even within a family. NF1 is characterized by multiple cafe au lait spots, axillary and inguinal freckling, multiple discrete dermal neurofibromas, and iris Lisch nodules. Learning disabilities are frequent. Less common but potentially more serious manifestations include plexiform neurofibromas, optic and other central nervous system gliomas, malignant peripheral nerve sheath tumors, vasculopathy, and osseous lesions.

CURRENT KNOWLEDGES AND KEY POINTS

Since the original National Institutes of Health consensus Development Conference in 1987, there have been significant progress toward a more complete understanding of the molecular-bases for neurofibromatosis 1 and the routine follow-up for the care of the NF1 patients. The authors review the present data on the clinical and molecular aspects of the neurofibromatosis 1.

FUTURE PROSPECTS AND PROJECTS

NF1 requires life-long management adapted to age and multidisciplinary structures are particularly well adapted to the diversity of the manifestations of this pathology. The French NF-France Network has been created in 2001 to federate the French multidisciplinary structures for neurofibromatosis and harmonize the follow-up of NF1 patients in France.

Analysis of neurofibromatosis 1 (NF1) lesions by body segment

Café-au-lait spots and neurofibromas are defining features of neurofibromatosis 1 (NF1), but they vary greatly in number, size, and clinical importance from patient to patient. The cause of this variability is unknown. We tested the hypotheses that development of these lesions is influenced by local or familial factors. The presence or absence of café-au-lait spots, cutaneous neurofibromas, and diffuse plexiform neurofibromas was recorded for each of 10 divisions of the body surface in 547 NF1 patients, including 117 affected individuals in 52 families. We used stratified Mantel-Haenszel tests to look for local associations between the presence of diffuse plexiform neurofibromas, cutaneous neurofibromas, and café-au-lait spots in individual body segments of NF1 patients. We used a random effects model to obtain intrafamilial correlation coefficients for the age-adjusted number of body divisions affected with each of the three lesions. No significant association was observed between the occurrence of cutaneous and diffuse plexiform neurofibromas, between café-au-lait spots and cutaneous neurofibromas, or between café-au-lait spots and plexiform neurofibromas in the same body segment. The correlation among relatives in the number of body segments affected with café-au-lait spots was 0.45 (95% confidence interval [CI] = 0.18-0.71), with cutaneous neurofibromas, 0.37 (95% CI = 0.15-0.55), and with plexiform neurofibromas, 0.35 (95% CI = 0.15-0.57). We conclude that the development of café-au-lait spots, cutaneous neurofibromas, and plexiform neurofibromas are spatially independent in NF1 patients but that the development of all three lesions is influenced by familial factors.

Neurofibromatosis 1: clinical manifestations and diagnostic criteria

Neurofibromatosis 1 occurs in 2 to 3 people per 10,000. The most frequent clinical features are café-au-lait macules, neurofibromas, intertriginous freckling, Lisch nodules, and learning disabilities, but optic and other gliomas, malignant peripheral nerve sheath tumors, and characteristic osseous lesions also can be present. Two striking aspects of neurofibromatosis 1 are its progressive nature and its extreme variability. This article reviews the natural history and some important clinical manifestations of neurofibromatosis 1, with emphasis on features that constitute the standard diagnostic criteria. The pathogenic implications of these clinical manifestations are also considered.

Genetics of neurofibromatosis 1 and the NF1 gene

Neurofibromatosis 1 serves as a paradigm for understanding the principles of human genetics. The concepts of gene mutation, penetrance of the condition, variable clinical expressivity, mosaicism, age-dependent expression of clinical manifestations, and pleiotropy are evident in this autosomal dominant condition. The lack of genotype-phenotype correlation, except the whole-gene deletion phenotype, leads to speculation on modifiers of the haploinsufficient state of the NF1 gene product neurofibromin. The variant form of neurofibromatosis, neurofibromatosis Noonan's syndrome, suggests potential interaction of independent biochemical pathways. Identification of the NF1 gene led to the discovery of its role in ras signal transduction. Neurofibromin is a negative regulator of intracellular ras signaling. This observation now provides the framework for the development of rational medical therapies. In addition, knowledge of the molecular basis of the variable expression of clinical manifestations could provide better anticipatory guidance and more effective management of the medical complications that are associated with this condition.

NF1 mutations and molecular testing

Neurofibromatosis 1 is a progressive autosomal dominant condition caused by mutations in the NF1 gene on chromosome 17. The condition shows clinical variable expressivity, with varying features even between family members who share the same mutation. Furthermore, it is impossible to precisely predict the severity and course of the condition, a source of frustration for families and physicians. Neurofibromatosis 1 is also heterogeneous at the mutation level, with more than 300 independent mutations having been reported in this gene. The mutation data have accumulated slowly owing to the variability of the mutation types and the size and complexity of the gene. This is also reflected in the lack of a simple, inexpensive, highly accurate DNA-based test for neurofibromatosis 1 at present. This article reviews current NF1 mutation spectrum and testing, discussing and illustrating mutation mechanisms and pathogenetic effects, as well as factors affecting DNA testing and interpretation/diagnosis.

Analysis of intrafamilial phenotypic variation in neurofibromatosis 1 (NF1)

The relationship of genetic factors to variable expressivity in neurofibromatosis 1 (NF1) is poorly understood. We examined familial aggregation of NF1 features among different classes of affected relatives. Clinical information was obtained from the National NF Foundation International Database on 904 affected individuals in 373 families with 2 or more members with NF1. We used multivariate probit regression to measure the associations between various classes of relatives for each of 10 clinical features of NF1, while simultaneously adjusting for covariates including related features, age, and gender. Two distinct patterns were observed when we compared associations between first- and second-degree relatives, sibs, and parent-child pairs: Lisch nodules and café-au-lait spots had greater associations between first-degree relatives than between second-degree relatives, while subcutaneous neurofibromas, plexiform neurofibromas, café-au-lait spots, and intertriginous freckling had greater associations between sibs than between parents and children. In addition, Lisch nodules, subcutaneous neurofibromas, and cutaneous neurofibromas had greater associations between affected fathers and children than between affected mothers and children. These familial patterns suggest that unlinked modifying genes and the normal NF1 allele may both be involved in the development of particular clinical features of NF1, but that the relative contributions vary for different features.

Association of piebaldism and neurofibromatosis type 1 in a girl

We report an 11-year-old girl with both piebaldism and neurofibromatosis type 1 (NF1). The patient had large depigmented patches on her lower limbs and a white forelock since birth. In addition, some café au lait spots were present on her trunk at birth and had increased in number and size during childhood in concomitance with the appearance of axillary and inguinal freckling. Neither neurofibromas nor Lisch nodules were detected and the patient was otherwise healthy. Pedigree analysis revealed inheritance for piebaldism on the paternal side. To our knowledge, the association of piebaldism and NF1 has been described previously in only three patients. Awareness of this rare association is relevant to ensure early diagnosis and adequate follow-up for NF1.

Associations of clinical features in neurofibromatosis 1 (NF1)

Neurofibromatosis 1 (NF1), an autosomal dominant disease, exhibits extreme clinical variability. This variability greatly increases the burden for affected families and impairs our ability to understand the pathogenesis of NF1. Recognition of heterogeneity within a disease may provide important pathogenic insights, therefore we tested clinical data from three large sets of NF1 patients for evidence that certain common features are more likely to occur in some NF1 patients than in others. Clinical information on 4,402 patients with NF1 was obtained from three independent databases. We examined associations between pairs of clinical features in individual affected probands. We also examined associations between the occurrence of individual features in affected relatives. Associations were summarized as odds ratios with 95% confidence intervals. We found associations between several pairs of features in affected probands: intertriginous freckling and Lisch nodules, discrete neurofibromas and plexiform neurofibromas, discrete neurofibromas and Lisch nodules, plexiform neurofibromas and scoliosis, learning disability or mental retardation and seizures. We also found associations between the occurrence of Lisch nodules, macrocephaly, short stature, and learning disability or mental retardation as individual features in parents and children with NF1. Our observations suggest that, contrary to established belief, some NF1 patients are more likely than others to develop particular manifestations of the disease. Genetic factors appear to determine the development of particular phenotypic features.

Neurology and the skin

As knowledge of pathophysiology grows, so does the refinement of diagnoses. Sometimes increased knowledge permits consolidation and unification. Unfortunately, at our present level of understanding, it usually demands proliferation of diagnostic categories. As tedious as this diagnostic splintering may seem, such is the price currently exacted of both the investigator and the clinician who seek to optimise management. Increased diagnostic refinement often requires inquiry into matters outside the bounds of one's specialty. Most often we turn to the radiologist or to the laboratory to narrow the differential diagnosis generated from the history and neurological examination. As we have shown, a useful intermediate step is extension of the physical examination to organs such as the skin, which are not the traditional preserve of the neurologist. That any text could confer the sophistication required for expert dermatological diagnosis is an unrealistic expectation. However, we hope that this review will encourage careful examination of the skin, hair, and nails by the neurological practitioner, with consideration of referral to a dermatologist when greater expertise is required.

Neurofibromatosis 1 in childhood

Neurofibromatosis 1 (NF1) is an autosomal-dominant disorder with an incidence of approximately 1 in 3,000. The cardinal features of the disorder are cafe au lait spots, axillary freckling, cutaneous neurofibromas, and iris hamartomas (Lisch nodules). Common complications include learning disability, scoliosis, and optic gliomas. Other complications (e.g., peripheral nerve malignancy, bony deformities, and epilepsy) are individually rare. The mainstay of care for patients with NF1 is anticipatory guidance, and the early detection and symptomatic treatment of disease complications. Counseling of patients and their families should provide a realistic overview of possible disease complications, while emphasizing that most individuals with NF1 lead healthy and productive lives. The gene for NF1 has been identified, and future cell biology research will focus on understanding the pathogenetic mechanisms that underly the diverse manifestations of the disorder.

A clinical variant of neurofibromatosis type 1: familial spinal neurofibromatosis with a frameshift mutation in the NF1 gene

Spinal neurofibromatosis (SNF) has been considered to be an alternative form of neurofibromatosis in which spinal cord tumors are the main clinical characteristic. Familial SNF has been reported, elsewhere, in three families-two linked to markers within the gene for neurofibromatosis type 1 (NF1) and the other not linked to NF1-but no molecular alterations have been described in these families. We describe a three-generation family that includes five members affected by SNF. All the affected members presented multiple spinal neurofibromas and café au lait spots, one member had cutaneous neurofibromas, and some members had other signs of NF1. Genetic analysis, performed with markers within and flanking the NF1 gene, showed segregation with the NF1 locus. Mutation analysis, performed with the protein-truncation test and SSCP/heteroduplex analysis of the whole coding region of the NF1 gene, identified a frameshift mutation (8042insA) in exon 46, which should result in a truncated NF1 protein. The 8042insA mutation was detected in all five family members with the SNF/NF1 phenotype. To our knowledge, this is the first time that a mutation in the NF1 gene has been associated with SNF. The clinical homogeneity in the severity of the disease among the affected members of the family, which is unusual in NF1, suggests that a particular property of the NF1 mutation described here, a gene closely linked to NF1, or posttranscriptional events are involved in this severe neurological phenotype.