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Disorders of Keratinization and Other Genodermatoses
Published in Ayşe Serap Karadağ, Lawrence Charles Parish, Jordan V. Wang, Roxburgh's Common Skin Diseases, 2022
Roselyn Stanger, Nanette Silverberg
Differential diagnosis: There are many other syndromes associated with café au lait spots including Legius syndrome, which can mimic NF1 in the skin but lacks the neurological changes. NF-1, McCune Albright syndrome, and Legius syndrome are all associated with café au lait macules.
Central nervous system: Paediatric and neurodevelopmental disorders
Published in Angus Clarke, Alex Murray, Julian Sampson, Harper's Practical Genetic Counselling, 2019
A more severe phenotype is often found in those whose mutation is a whole gene deletion of NF1. A milder variant is caused by a specific 3 bp deletion and typically causes cafe-au-lait patches but very few tumours. NF1 is also milder when it is segmental, arising by somatic mutation, but any affected children of such a parent will be fully affected. An important differential diagnosis of NF1 is Legius syndrome, caused by mutations in SPRED1, in which skin pigmentation and other features are found but in which Lisch nodules and tumours are unlikely to develop.
Genodermatoses
Published in Dimitris Rigopoulos, Alexander C. Katoulis, Hyperpigmentation, 2017
In Legius syndrome (NF1-like syndrome), a heterozygous mutation in the SPRED1 gene is responsible for the phenotype. Individuals with Legius syndrome present with multiple café-au-lait spots with or without freckling. Diagnosis based on clinical features alone is not possible, because of the important clinical overlap with NF1. Learning disabilities, developmental delay, hyperactivity, autistic behavior, and concentration problems are frequently reported in children with Legius syndrome. On the other hand, patients do not show some associations with NF1 tumors, such as optic pathway gliomas and neurofibromas, bone abnormalities, or Lisch nodules. The intense medical surveillance that is needed for NF1 is not required in this syndrome.10
A Narrative Review of the Ocular Manifestations in Noonan Syndrome
Published in Seminars in Ophthalmology, 2022
Evita Evangelia Christou, Paraskevas Zafeiropoulos, Dimitrios Rallis, Maria Baltogianni, Christoforos Asproudis, Maria Stefaniotou, Vasileios Giapros, Ioannis Asproudis
The RASopathies are a clinically defined group of medical genetic syndromes.5,13,20 Regarding the wide spectrum of clinical entities of these syndromes, distinct disorders have been described; (a) neurofibromatosis type 1, (b) Noonan syndrome, (c) Noonan syndrome with multiple lentigines (formerly referred as LEOPARD syndrome), (d) capillary malformation–arteriovenous malformation syndrome, (e) Costello syndrome, (f) cardio-facial-cutaneous syndrome and (g) Legius syndrome. The pathogenesis of RASopathies is associated with germline mutations in genes encoding components or regulators of the RAS/MAPK pathway.5,13,20 The RAS/MAPK pathway is critical for signal transduction through extracellular ligands (growth factors, cell adhesion molecules, cytokines, and hormones) with an essential role in regulating the cell cycle, proliferation, differentiation, and metabolism. Indeed, it plays a vital role in embryonic and postnatal development.
Emerging therapeutic targets for neurofibromatosis type 1
Published in Expert Opinion on Therapeutic Targets, 2018
James A. Walker, Meena Upadhyaya
The most common nonneoplastic manifestations in NF1 are pigmentary features, including CALMs which are dense populations of melanocytes observed in 99% of NF1 patients and are used in early childhood diagnosis. Cognitive and behavioral deficits occur in 65–80% of children with NF1. Specific learning disabilities affecting performance in visuospatial tasks, literacy skills, and oral and written expression often lead to poor academic performance [10]. Further, attention-deficit hyperactivity disorder (ADHD) symptoms such as decreased impulse control and planning ability have also been observed [11]. Other non-tumor symptoms in NF1 include skeletal abnormalities, iris hamartomas (Lisch nodules), and reduced overall growth. NF1 patients are also at increased risk of developing neurofibromatous neuropathies [12]. Cardiovascular manifestations of NF1 include vasculopathy, hypertension, and congenital heart defects. Patients with constitutional mismatch repair deficiency (CMMRD) and Legius syndrome (caused by germline SPRED1 mutation) may have overlapping clinical symptoms, underlying the need for molecular diagnosis [13].
The presence and progression of choroidal neurofibromas in a predominantly pediatric population with neurofibromatosis type-1
Published in Ophthalmic Genetics, 2021
Corina M. Chilibeck, Shaheen Shah, Heather C. Russell, Andrea L. Vincent
Obtaining a definitive diagnosis of NF1 may take years as many of the clinical diagnostic criteria exhibit age-specific penetrance, and genetic testing for NF1, which is not part of the NIH diagnostic criteria, has moderate sensitivity and is not routinely undertaken in our region; it was performed in only 5.7% of our study cohort. One patient tested negative for pathogenic variants in NF1, but subsequently met the NIH diagnostic criteria, so may have an undetected pathogenic variant in NF1 or other loci (24). The two patients with SPRED1-associated Legius syndrome had no choroidal abnormalities, as previously observed (25).