A Novel Heterozygous NF1 Variant in a Neurofibromatosis-Noonan Syndrome Patient with Growth Hormone Deficiency: A Case Report

Neurofibromatosis-Noonan syndrome: a prospective monocentric study of 26 patients and literature review

BACKGROUND

Data on clinical manifestations of neurofibromatosis-Noonan syndrome (NF-NS) remain heterogeneous, with limited validated descriptions.

METHODS

This study aims to better define the clinical and molecular features of NF-NS and compare them with existing literature. Secondary objectives include evaluating inter-rater diagnostic agreement among experienced clinicians and assessing the utility of deep-learning algorithms (Face2Gene® [F2G]). Additionally, we assess the prevalence of congenital heart malformations (CHM) in NF-NS compared to 'classic' neurofibromatosis type 1 (NF1). A 9-year, prospective, monocentric study was conducted, involving patients with NF1 pathogenic variants (PVs) and Noonan syndrome-like facial phenotype (NSLFP).

RESULTS

Twenty-six patients were enrolled. NSLFP was categorized as 'suggestive' in 69% of cases and 'typical' in 31%. The presence of at least two facial abnormalities (e.g., low-set ears, downslanted palpebral fissures, hypertelorism, and ptosis) was consistently observed in 'typical' cases. Inter-rater concordance was substantial (0.65 [95% CI = 0.56; 0.74]), while concordance between clinicians and F2G was almost perfect at (0.821 [CI 95% = 0.625; 1.000]). Missense NF1 PVs were observed in 38.5% of cases. Apart from NSLP and a high frequency of pectus excavatum (62.5%), no significant differences in anthropometric, dermatological, neurological, skeletal, or ocular clinical features were observed between NF-NS and 'classic' NF1. CHM were found in 19.2% of NF-NS patients, with pulmonic stenosis present in 7.7%.

CONCLUSION

NF-NS is a distinct phenotypic variant of NF1, marked by NSLP with consistent facial features -, and frequent pectus excavatum. F2G demonstrated high diagnostic concordance, reinforcing its clinical utility. Given the elevated risk of CHM, especially pulmonic stenosis, proactive cardiovascular assessment similar to other RASopathies is recommended for NS-NF patients, regardless of NF1 PV type.

Portraying the full picture of Neurofibromatosis-Noonan syndrome: a systematic review of literature

BACKGROUND AND AIMS

Neurofibromatosis-Noonan syndrome (NFNS) is an extremely rare genetic entity combining the clinical phenotype of two conditions: neurofibromatosis type 1 syndrome (NF1) and Noonan syndrome (NS). Nevertheless, many inconsistencies reside in our understanding of this condition, mainly its clinical features and genetic background. Through this systematic review, we aim to shed light on the epidemiological features, the broad clinical spectrum, the underlying genetic defects and the associated comorbidities of NFNS.

METHODS

Medline, Scopus and Google Scholar were searched for publications on the clinical and genetic features of patients with NFNS. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed and the study protocol was registered in PROSPERO.

RESULTS

Of 951 records screened, 42 were eligible. The mean age at diagnosis was 14.7 years ranging from 0 to 69 years. As for the circumstance of discovery of NFNS, it was dominated by family investigation followed by neurofibromas, facial dysmorphia and short stature (SS). Prematurity was noted in 40.9% of cases. The hallmark features of NFNS at diagnosis were 'café au lait' macules, typical facial dysmorphia of NS, postnatal SS, pectus abnormalities, broad neck and lentigines. Macrocephaly, scoliosis and cardiopathies occurred in 26%, 42.4% and 36.9% of cases, respectively. Tumours were found in 18.4% of cases. As for the genetic foundation of NFNS, NF1 gene mutations were depicted in 87.5% of individuals.

CONCLUSIONS

Based on our findings, we emphasise on the importance of searching for NS features in patients with NF1 since the prognosis, comorbidities and consequently management could be altered.

PROSPERO REGISTRATION NUMBER

42024522238.

Neurofibromatosis-Noonan syndrome and growth deficiency in an Iranian girl due to a pathogenic variant in NF1 gene

BACKGROUND

Mutations in NF1 gene could cause allelic disorders with clinical spectrum of Neurofibromatosis type 1 to Noonan syndrome. Here, a 7-year-old Iranian girl is described with Neurofibromatosis-Noonan syndrome due to a pathogenic variant in NF1 gene.

METHODS

Clinical evaluations were performed along with genetic testing using whole exome sequencing (WES). The variant analysis including pathogenicity prediction was also done using bioinformatics tools.

RESULTS

The chief compliant of the patient was short stature and lack of proper weight gain. Other symptoms were developmental delay, learning disability, inadequate speech skill, broad forehead, hypertelorism, and epicanthal folds, low set ears and webbed neck. A small deletion, c.4375-4377delGAA, was found in NF1 gene using WES. This variant was classified as pathogenic according to ACMG.

CONCLUSIONS

NF1 variants may show variable phenotypes among the patients; identifying such variants is helpful in therapeutic management of the disease. WES is considered as an appropriate test to diagnose Neurofibromatosis-Noonan syndrome.