This is the first case reported from Egypt for a child with NF1 and associated multiple rare congenital anomalies. The diagnosis of NF1 in this case relied on meeting the revised diagnostic criteria for NF1 [4], including plexiform neurofibroma, sphenoid dysplasia, heterozygous pathogenic NF1 variant, and a parent meeting diagnostic criterion of NF1. Other typical features included scoliosis, café-au-lait macules, hydrocephalus, and spinal neurofibromas. Moreover, the child had a constellation of several unusual abnormalities: bilateral congenital glaucoma, giant congenital melanocytic nevi, scalp alopecia, and distal penile hypospadias. A few reports exist on the rare association of each of these congenital anomalies with NF1. However, the constellation of multiple congenital abnormalities in a single NF1 patient has not been reported. Importantly, associated congenital anomalies could be the presenting features in patients with NF1 since typical diagnostic features of NF1 may not be apparent in the neonatal period and early infancy.

The underlying mechanism linking these diverse congenital anomalies with NF1 is likely the disruption of Ras/mitogen-activated protein kinase (MAPK) pathway, which plays a pivotal role in the regulation of cell cycle. NF1 is a tumor suppressor gene encoding neurofibromin. Neurofibromin is a GTPase-activating protein (also called RasGAP), which downregulates the RAS/MAPK pathway [15]. Accordingly, NF1 shares multiple clinical manifestations and congenital anomalies with other RASopathies, such as Noonan (MIM 163950), Costello (MIM 218040), LEOPARD (MIM 151100), Cardiofaciocutaneous (MIM 115150), Legius (MIM 611431), and capillary malformation-arteriovenous malformation (CMAVM; MIM 608354) syndromes [16]. Indeed, vascular and nevi malformations, ocular anomalies, hair abnormalities, and urogenital anomalies are among the reported congenital anomalies in patients with RASopathies [15, 17].

Glaucoma has been found in about 1–2% of patients with NF1. However, the presence of eyelid plexiform neurofibroma, like in our case, is associated with ipsilateral glaucoma in up to 50% of NF1 patients [18, 19]. Possible mechanisms of primary glaucoma associated with NF1 include RAS/MAPK-mediated developmental abnormalities in the iridocorneal angle; direct infiltration of anterior chamber angle by neurofibromas; secondary angle closure due to infiltration of ciliary body and choroid by neurofibromas; and fibrovascularization causing synechial angle closure and neovascular glaucoma [19, 20]. The presence of glaucoma at birth suggests a developmental abnormality of the iridocorneal angle, while onset at an older age indicates infiltration of the anterior chamber angle by neurofibromas or other mechanisms. There have been several reports on children with NF1 who had congenital glaucoma as the first presenting feature [18, 21,22,23,24]. Furthermore, glaucoma has been described in patients with other RASopathies, such as Noonan syndrome and oculocutaneous mosaic RASopathies [25,26,27]. Interestingly, NF1 patients with congenital glaucoma commonly have progressive globe enlargement even after control of intraocular pressure; this could be attributed to local growth factors secreted by neurofibromatous tissue or ptosis-related disruption of normal emmetropization with subsequent development of axial myopia [19, 28]. Management is challenging due to the common coexistence of bone dysplasia and tumors in the eyelid and orbit, leading to generally poor visual prognosis [19, 23].

GCMN has been described in several NF1 children with an estimated prevalence of 5% [29,30,31]. Furthermore, Ekure et al.[6] reported an African NF1 child with GCMN, ambiguous genitalia, and ventricular septal defect. Of note, neurofibromas and GCMN arise from Schwann cells and melanocytes, respectively, both of which have a common origin from the neural crest stem cells [29, 30]. This indicates the important role of RAS/MAPK pathway in neural crest development [15]. Indeed, vascular and melanocytic nevus malformations are common features among other RASopathies, such as CMAVM syndrome, cardiofaciocutaneous syndrome, Noonan syndrome with multiple lentigines, and oculocutaneous mosaic RASopathies [15,16,17, 26]. Importantly, NF1 and GCMN are individually associated with increased risk for neural crest malignancies, including melanoma [3, 30,31,32]. Therefore, patients with coexistent NF1 and GCMN likely have a cumulatively higher risk of malignancy.

Alopecia has rarely been reported in association with NF1. Mizukami et al.[33] reported a 52-year-old man with NF1 presented with alopecia areata. Furthermore, two NF1 children have been reported with alopecia areata, one of whom had associated autoimmune thyroiditis and the other had vitiligo, suggesting an association between NF1 and autoimmunity [34, 35]. However, alopecia in our case was present since birth, which indicates congenital etiology rather than autoimmunity. Similarly, Ghosh et al.[7] reported an NF1 child with right frontal congenital alopecia in association with proptosis, facial dysmorphism and hemihypertrophy, vocal cord palsy, and plexiform neurofibroma. We speculate that alopecia in this case may be related to NF1 variant-mediated dysregulation of RAS/MAPK pathway, which serves a crucial role in hair development and growth [36]. Indeed, hair abnormalities have been described in other RASopathies, such as synophrys and trichomegaly in Costello syndrome [36], sparse scalp hair in Noonan syndrome [17], and scalp alopecia in Noonan syndrome with loose anagen hair syndrome, cardiofaciocutaneous syndrome, and oculocutaneous mosaic RASopathies [17, 26].

Hypospadias is one of the most frequent congenital anomalies in males, which may occur as an isolated anomaly or be associated with other genetic defects [37]. The association of hypospadias and NF1 has been reported once in a Colombian male child with a coexistent pathogenic NR5A1 variant that is associated with sex disorders [38]. Of note, Ras-MAPK pathway is critical for the differentiation of male external genitalia [37]. Urogenital anomalies have been demonstrated in patients with other RASopathies, such as Noonan and LEOPARD syndromes [16]. Interestingly, certain variants in BRAF gene, which is the causal gene for several RASopathies, have been associated with hypospadias through reducing the transcription of SRY gene [37]. Taken together, the rare association between hypospadias and NF1 reported herein indicates a potential role of NF1 in urogenital development, although further studies are warranted to elucidate the underlying functional mechanisms.

Spinal neurofibromas occur in about 40% of patients with NF1, most of which are asymptomatic particularly in infancy and early childhood. These lesions are more likely associated with missense or splice-site germline mutations [3, 39]. In a large cohort of 514 adult patients with NF1, 28% had intraspinal tumors (affecting cervical, lumbosacral, and thoracic regions in descending order of frequency) while 21.8% had extraspinal tumors [40]. However, severe symmetric involvement is less commonly reported particularly at this young age [39]. In a study on 53 children with NF1, spinal MRI detected spinal neurofibromas in seven (13.2%), all of which were asymptomatic [41]. The presence of multiple bilateral spinal tumors but only a few NF1 criteria suggest spinal neurofibromatosis subtype, although this condition may also occur in typical NF1 such as in our case report [1, 2, 42, 43]. Early onset and extensive spinal neurofibromas such as in our case are usually associated with severe motor and sensory impairment and poor prognosis at later age [41]. No definitive chemotherapy is currently available for spinal neurofibromas; surgical excision is typically reserved for severe cases, considering the anatomical site, extent of invasion, risk of recurrence, and patient preference [41,42,43].

The case reported herein had hydrocephalus, hypotonia, and developmental delay, which have been previously reported in patients with NF1. Hydrocephalus affects approximately 5% of children with NF1 and is commonly obstructive due to tumors (mostly gliomas) or aqueduct stenosis; idiopathic aqueduct stenosis may occur in 1.5–2% of patients with NF1 [44]. Hypotonia and muscle weakness are frequent features in children with NF1 as well as other RASopathies [45]. This has been classically attributed to nerve dysfunction; however, evidence from mouse studies indicates that NF1 is associated with low levels of key mitochondrial lipid transporters leading to lipid storage-like myopathy [46]. Finally, the developmental delay in this case may be secondary to several causes, including nerve affection, NF1-associated myopathy, severe hydrocephalus, and extensive spinal neurofibromatosis.

WES of this case revealed a heterozygous c.1466A > G NF1 variant, which has been previously reported as pathogenic with strong evidence in several patients with no specific genotype–phenotype correlation (ClinVar ID: VCV000000354.80) [47, 48]. The nucleotide change creates a cryptic splice donor site, resulting in skipping of the last 62-bp (c.1466_1527del) at exon 13 with the formation of a stop codon at amino acid 489 [47]. Although NF1 is usually diagnosed on clinical grounds, genetic testing is an important means for the diagnosis of cases with atypical features and the provision of genetic counseling. Furthermore, genetic testing could have prognostic implications since certain NF1 variants seem to correlate with clinical phenotype [1, 3].

The present case report has some limitations. First, while our case had normal chromosomal karyotyping and no other clinically significant variants in WES, the possibility of having coexistent intronic or other complex genetic abnormalities contributing to some of patients’ manifestations cannot be absolutely excluded. Another limitation is related to the irregular patient follow-up, which did not allow complete characterization of patient’s features over time. Last, this case report did not include advanced laboratory and functional studies to unravel the underlying pathophysiological mechanisms by which the identified c.1466A > G NF1 variant could contribute to the described multiple congenital anomalies. Additional large and longitudinal follow-up studies are required to better delineate atypical features of NF1. Furthermore, functional studies should investigate how the effects of NF1 variants on RAS/MAPK pathway and other genes’ expression/function could contribute to diverse congenital anomalies.

In conclusion, the present case report adds to the knowledge of the phenotypic spectrum and variability of NF1 by reporting the association of multiple unusual features in an Egyptian child with NF1. Importantly, such congenital anomalies could be the first presenting features in patients with NF1 since cafe´-au-lait macules and other typical diagnostic criteria may not be apparent in the neonatal period and early infancy. Accordingly, NF1 should be considered in newborns with congenital glaucoma, GCMN, alopecia, and hypospadias.