Diagnostic delay in neurofibromatosis type 1

Expanding the phenotype of neurofibromatosis type 1 microdeletion syndrome

Neurofibromatosis type 1 (NF-1) microdeletion syndrome accounts for 5 to 11% of individuals with NF-1. The aim of our study was to characterize a large cohort of individuals with NF-1 microdeletion syndrome and expand its natural history. We conducted a retrospective chart review from 1994 to 2024 of individuals with NF-1 microdeletion syndrome followed at two large Neurofibromatosis Clinics. This cohort consists of 57 individuals with NF-1 microdeletion syndrome (28 type-1, 4 type-2, 2 type-3, 9 atypical deletions, and 14 indeterminate). We note 38/56 (67.9%) with describable facial features, 25/57 (43.8%) with plexiform neurofibromas, and 3/57 (5.2%) with malignant peripheral nerve sheath tumors within the observed period. The most reported neurodevelopmental manifestations from school-age or older individuals included 39/49 (79.6%) with developmental delays, 35/49 (71.4%) with expressive and/or receptive speech delays, 33/41 (80.5%) with learning difficulties, and 23/42 (54.8%) with attention-deficit/hyperactivity disorder. Full-scale IQ testing data was available for 22 individuals (range: 50-96). Of the 21 adults in this cohort, 14/21 (66.7%) graduated from high school, and 4/21 (19.0%) had some college experience. Many individuals received academic support (i.e., special education, individual education plan). In this cohort, neurocognitive outcomes in adults varied more than typically reported in the literature.

Genotype-Phenotype Correlation in Neurofibromatosis Type 1: Evidence for a Mild Phenotype Associated with Splicing Variants Leading to In-Frame Skipping of NF1 Exon 24 [19a]

Neurofibromatosis type 1 (NF1) is an autosomal dominant neurocutaneous disorder caused by loss-of-function variants in the NF1 gene. As of 20 November 2023, over 5000 distinct pathogenic or likely pathogenic variants have been reported in public databases. However, only a few NF1 genotype-phenotype correlations have been established so far. In this study, we present findings on 40 individuals with NF1, comprising 26 unrelated probands and 14 affected relatives, who carry one of nine NF1 heterozygous pathogenic splicing variants, all of which result in the in-frame skipping of exon 24 [19a] (NM_000267.3:r.3114_3197del, p.Asn1039_Arg1066del). These variants include c.3114-2A>G, c.3114-1G>A, c.3196A>G, c.3197G>A, c.3197G>T, c.3197+1G>A, c.3197+1G>T, c.3197+2T>C, and c.3197+3A>T. Among individuals with these variants, none exhibit externally visible plexiform neurofibromas, histopathologically confirmed cutaneous or subcutaneous neurofibromas, symptomatic spinal neurofibromas, or symptomatic optic pathway gliomas. The most prevalent, and sometimes sole, clinical feature observed in this cohort is multiple café-au-lait macules, with or without skinfold freckles: 85% and 60.5% of the individuals display six or more café-au-lait macules and freckles, respectively. In comparison to established NF1 genotype-phenotype correlations, these patients demonstrate highly similar clinical presentations to those associated with the NF1 pathogenic variant c.2970_2972del (p.Met992del), known for resulting in the mildest clinical features. Despite the generally mild phenotype, cognitive impairment, developmental delay, and/or learning difficulties are still observed in 33.3% of these patients, suggesting that learning challenges remain a prominent aspect of the phenotypic presentation in these individuals and necessitate specialized care. This newly established genotype-phenotype correlation will assist clinicians in improving the management of patients harboring NF1 exon 24 [19a] skipping variants and provide a new therapeutic target for NF1 treatment.

Neurofibromatosis Type 1: Diagnostic Timelines in Children

BACKGROUND AND OBJECTIVES

The neurofibromatosis 1 (NF1) diagnosis is challenging in young children without a family history of NF1. The aims of this study were to estimate diagnostic delays in children without a family history of NF1 and to examine the effects of using café au lait macules and skin fold freckling as a single diagnostic criterion.

PATIENTS AND METHODS

Retrospective, descriptive, observational study of all patients diagnosed with NF1 before the age of 18 years who were seen at our hospital. The medical records of those included were reviewed to identify the date on which the diagnostic criteria of NF1 were objectified. The patients were categorized into 2 groups: those with a known parental history of NF1 and those without. Café au lait macules and skin fold freckling were assessed as a single diagnostic criterion, and genetic evidence was considered to confirm highly suspicious cases.

RESULTS

We studied 108 patients younger than the age of 18 years with a diagnosis of NF1. Mean (SD) age at diagnosis was 3.94 (±3.8) years for the overall group, 1 year for patients with a parental history of NF1, and 4 years and 8 months for those without. Diagnosis was therefore delayed by 3 years and 8 months in patients without a family history.

CONCLUSION

Skin lesions were the first clinical manifestation of NF1 in most patients. We believe that the National Institutes of Health's diagnostic criteria for NF1 should be updated to aid diagnosis in young children.

[Translated article] Neurofibromatosis Type 1: Diagnostic Timelines in Children

BACKGROUND AND OBJECTIVES

Diagnosis of neurofibromatosis 1 (NF1) diagnosis is challenging in young children without a family history of NF1. The aims of this study were to estimate diagnostic delays in children without a family history of NF1 and to examine the effects of considering café-au-lait macules and skinfold freckling as a single diagnostic criterion.

PATIENTS AND METHODS

Retrospective, descriptive, observational study of all patients diagnosed with NF1 before the age of 18 years who were seen at our hospital. The medical records of those included were reviewed to identify the date on which the diagnostic criteria of NF1 were objectified. The patients were categorized into 2 groups: those with a known parental history of NF1 and those without. Café-au-lait macules and skinfold freckling were assessed as a single diagnostic criterion, and genetic evidence was considered to confirm highly suspicious cases.

RESULTS

We studied 108 patients younger than the age of 18 years with a diagnosis of NF1. Mean (SD) age at diagnosis was 3.94 (±3.8) years for the overall group, 1 year for patients with a parental history of NF1, and 4 years and 8 months for those without. Diagnosis was therefore delayed by 3 years and 8 months in patients without a family history.

CONCLUSION

Skin lesions were the first clinical manifestation of NF1 in most patients. We believe that the National Institutes of Health's diagnostic criteria for NF1 should be updated to aid diagnosis in young children.

Challenges in the diagnosis of neurofibromatosis type 1 (NF1) in young children facilitated by means of revised diagnostic criteria including genetic testing for pathogenic NF1 gene variants

Neurofibromatosis type 1 (NF1) is the most frequent disorder associated with multiple café-au-lait macules (CALM) which may either be present at birth or appear during the first year of life. Other NF1-associated features such as skin-fold freckling and Lisch nodules occur later during childhood whereas dermal neurofibromas are rare in young children and usually only arise during early adulthood. The NIH clinical diagnostic criteria for NF1, established in 1988, include the most common NF1-associated features. Since many of these features are age-dependent, arriving at a definitive diagnosis of NF1 by employing these criteria may not be possible in infancy if CALM are the only clinical feature evident. Indeed, approximately 46% of patients who are diagnosed with NF1 later in life do not meet the NIH diagnostic criteria by the age of 1 year. Further, the 1988 diagnostic criteria for NF1 are not specific enough to distinguish NF1 from other related disorders such as Legius syndrome. In this review, we outline the challenges faced in diagnosing NF1 in young children, and evaluate the utility of the recently revised (2021) diagnostic criteria for NF1, which include the presence of pathogenic variants in the NF1 gene and choroidal anomalies, for achieving an early and accurate diagnosis.

Congenital cutaneous neurofibromas in neurofibromatosis type 1: Clinicopathological features in early infancy

BACKGROUND AND OBJECTIVE

Clinicopathological features of cutaneous neurofibromas presenting as large irregularly shaped congenital café-au-lait macules (CALM) in Neurofibromatosis type 1 (NF1) patients have not been well characterized. We aimed to analyze the histopathological findings of large "atypical" CALM in children with NF1.

PATIENTS AND METHODS

In this retrospective observational study we analyzed histopathological and immunostaining features of 21 biopsy specimens from 18 large hyperpigmented macules with irregular borders with or without hypertrichosis present during the first months of life in NF1 diagnosed children.

RESULTS

Of the 21 biopsies, ten showed a diffuse neurofibroma pattern and four exhibited characteristics of plexiform neurofibroma (PNF). In twelve specimens we observed groups of fusiform cells arranged linearly mimicking a small caliber nerve trunk with abnormal morphology. Repeated biopsies from two of these lesions performed at different ages showed transformation to a plexiform pattern. An increased interstitial cellularity was observed in 17 samples that was more evident around eccrine glands in 16 or accompanying hair follicles and vascular structures in twelve samples. All these cells had immunoreactivity for S100-protein, CD68 and were Melan-A positive in 15 samples.

CONCLUSION

Clinicopathological findings of congenital cutaneous neurofibromas provide early diagnostic clues of NF1 with high relevance for monitoring of these patients.

Ultrasound as a diagnostic aid in identifying neurofibromas

Neurofibromatosis 1 is a multisystem disorder associated with substantial clinical variability. During childhood, few neurofibromas and café au lait spots may be the only manifest symptoms, making correct and timely diagnosis difficult. Herein we describe the clinical usefulness of ultrasound examination in identifying neurofibromas.

Clinical sensitivity and specificity of multiple T2-hyperintensities on brain magnetic resonance imaging in diagnosis of neurofibromatosis type 1 in children: diagnostic accuracy study

Aim

To determine the prevalence, number, and location of multiple (≥2) T2-hyperintensities on brain magnetic resonance imaging (MRI) in children with neurofibromatosis type 1 (NF1) and their correlation with age, and to establish their sensitivity, specificity, and accuracy for the diagnosis of NF1 in children, especially in the early age (2-7 years).

Methods

We performed a cross-sectional study of 162 patients with NF1 from Croatian Neurofibromatosis Association Database and 163 control children between the ages of 2 and 18 years who underwent brain MRI between 1989 and 2009.

Results

Multiple T2-hyperintensities were present in 74% of NF1 patients and 1.8% of controls. They were mainly located in the basal ganglia, brainstem, and cerebellum and were significantly decreased in prevalence and number in the older age. T2-hyperintensities had excellent diagnostic accuracy with the area under the receiver operating characteristic (ROC) curve of 0.849 and 95% confidence interval (CI) of 0.805-0.886. The diagnostic sensitivity, specificity, and accuracy rate of T2-hyperintensities for NF1 were highest in the youngest age (2-7 years): 81% (95% CI 71%-89.1%), 99% (95% CI 92.3%-100%), and 85.8 (95% CI 83.3-93.8), respectively.

Conclusion

This study strongly suggests the inclusion of T2-hyperintensities on brain MRI on the list of diagnostic criteria for NF1, especially in children of early age, when the clinical penetration of the NF1 gene has not yet been completely finished.

Neurofibromatosis 1: analysis of the demand for prenatal diagnosis in a French cohort of 361 patients

The severity of neurofibromatosis 1 and its variable expressivity make prenatal diagnosis appealing. We conducted our research to assess patient characteristics associated with the desire for prenatal diagnosis. Between 1995 and 2004, 361 neurofibromatosis 1 adult patients were interviewed about their desire for prenatal diagnosis. Answers were classified in three groups: (1) 'no;' (2) 'uncertain;' (3) 'yes.' Socio-demographical and clinical data were analyzed by logistic multinomial regression for their association with the desire for prenatal diagnosis. Male-to-female sex ratio was 0.93. Mean age at study +/- SD was 33.5 +/- 10. Seven four patients (20.5%) would consider prenatal diagnosis; 240 (66.5%) did not; and 47 (13.0%) were uncertain. In multivariate analysis, compared to the 'no' group, a longer follow-up (OR = 1.25 [1.11-1.41]), a younger age at study time (OR = 1.25 [1.11-1.41]), not having child (OR = 2.46 [1.03-5.97]) and a higher educational level (OR = 5.07 [1.05-24.47]) were independently associated with the 'yes' group. Compared to the 'no' group individuals who were in the 'uncertain' groups were younger (0.95 [0.90-0.99]), less often married (0.11 [0.01-0.89]) and had a longer follow-up (1.26 [1.09-1.46]). There is a significant demand for prenatal diagnosis among neurofibromatosis 1 French patients. This demand is associated with individuals who are younger, have no child, have a longer follow up, and higher level of education.

Genetic counselling for familial conditions during pregnancy: a review of the literature published during the years 1989-2004

BACKGROUND

Genetic counselling for familial conditions during pregnancy may have some disadvantages, such as time pressure and induced worry. However, little is known about the reasons for and consequences of this timing of genetic counselling.

OBJECTIVE

The objective of this study was to provide an overview of research aimed at the counselee's reasons for seeking genetic counselling during pregnancy and the medical-technical and procedural consequences thereof.

METHODS

We searched the databases Medline and PsycINFO for primary research papers, reviews and case reports, published from 1989 to June 2004.

RESULTS

No papers could be retrieved which explicitly addressed our research questions. However, 34 papers, out of a total of 399 papers, covered issues with some relevance to our research questions. Limited knowledge and alertness towards genetics and a greater apparent relevance of genetic issues during pregnancy seemed to explain, at least partly, the timing of referral during pregnancy. Literature on the consequences of this timing for the quality of the genetic counselling process appeared to be scarce. These consequences, therefore, remain unclear.

CONCLUSION

In the literature, little attention is paid to the various aspects of the timing of genetic counselling for familial conditions during pregnancy. More research on this issue is important, with a view to improving the care of pregnant women and their children.

Use of the national institutes of health criteria for diagnosis of neurofibromatosis 1 in children

OBJECTIVE

The National Institutes of Health (NIH) Diagnostic Criteria for neurofibromatosis 1 (NF1) are very useful clinically, but some individuals who are later shown to have NF1 cannot be diagnosed in early childhood using these criteria. The aim of this study is to determine the value of the NIH Diagnostic Criteria for NF1 in early childhood, to determine the age at which diagnosis can confidently be made, and to clarify the age at onset of the cardinal clinical features used in the NIH Diagnostic Criteria.

METHODS

We studied 1893 NF1 patients under 21 years old from the National Neurofibromatosis Foundation International Database to determine the age at which the features included in the NIH Diagnostic Criteria appear.

RESULTS

Approximately 46% of sporadic NF1 cases fail to meet the NIH Diagnostic Criteria by 1 year of age. Nearly all (97%; 95% confidence interval: 94-98) NF1 patients meet the criteria for diagnosis by 8 years old, and all do so by 20 years old. The usual order of appearance of the clinical features listed as NIH criteria is café-au-lait macules, axillary freckling, Lisch nodules, and neurofibromas. Symptomatic optic glioma is usually diagnosed by 3 years old, and characteristic osseous lesions are usually apparent within the first year of life.

CONCLUSION

The diagnosis of NF1 cannot always be made in young children using the NIH Diagnostic Criteria. Modification of these criteria may be necessary for children under 8 years old.

Minor disease features in neurofibromatosis type 1 (NF1) and their possible value in diagnosis of NF1 in children < or = 6 years and clinically suspected of having NF1. Neurofibromatosis team of Sophia Children's Hospital

OBJECTIVE

To establish the frequency of minor disease features in children with neurofibromatosis type 1 (NF1) and to evaluate the value of minor disease features in children < or = 6 years with a suspected diagnosis of NF1, considering that the disease is virtually 100% penetrant at 6 years of age.

DESIGN

During this 10 year, prospective, multidisciplinary, follow up study, 209 children suspected of having NF1 were examined; 150 were diagnosed with NF1 and 59 were not. The present analysis included children in whom NF1 was considered to be present at 6 years of age (n=85) and children without NF1 at 6 years of age (n=42).

RESULTS

The minor disease features macrocephaly (52.9%), short stature (24.7%), hypertelorism (63.5%), and thorax abnormalities (37.6%) were highly prevalent in children with NF1 and significantly associated with a diagnosis of NF1 at 6 years of age. In addition, the mean number of minor disease features was significantly higher in children with NF1 at 6 years of age compared to the group without a diagnosis at 6 years of age (mean 1.8 v 0.8, p<0.001). Moreover, children with three or more minor disease features were all diagnosed with NF1 under the age of 6 years. Multivariate analysis using a logistic regression model showed that macrocephaly, short stature, hypertelorism, and thorax abnormalities were all independently associated with the presence of NF1 at 6 years of age.

CONCLUSION

In children with insufficient diagnostic criteria aged < or = 6 years, documentation of minor disease features may be a helpful aid in predicting the diagnosis of NF1 in years to come.