Chinese patient with neurofibromatosis-Noonan syndrome caused by novel heterozygous NF1 exons 1-58 deletion: a case report

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

Neurofibromatosis-Noonan syndrome (NFNS), a rare autosomal-dominant hereditary disease, is characterized by clinical manifestations of both neurofibromatosis type 1 (NF1) and NS. We present a case of NFNS with short stature caused by a heterozygous nonsense variant of the NF1 gene. A 12-year-old boy was admitted because of short stature, numerous café-au-lait spots, low-set and posteriorly rotated ears, sparse eyebrows, broad forehead, and inverted triangular face. Cranial and spinal magnetic resonance imaging showed abnormal nodular lesions. Molecular analysis revealed a novel heterozygous c.6189 C > G (p.(Tyr2063*)) variant in the NF1 gene. The patient was not prescribed recombinant growth hormone (GH) therapy because exogenous GH may have enlarged the abnormal skeletal lesions. During follow-up, Lisch nodules were found in the ophthalmologic examination. NFNS, a variant form of NF1, is caused by heterozygous mutations in the NF1 gene. The mechanism of GH deficiency caused by NF1 is still unclear. Whether NFNS patients should be treated with exogenous GH remains controversial.

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.

LZTR1 molecular genetic overlap with clinical implications for Noonan syndrome and schwannomatosis

Background

Noonan syndrome (NS) is a genetic disorder characterized by developmental delays, typical facial gestalt and cardiovascular defects. LZTR1 variants have been recently described in patients with NS and schwannomatosis, but the association, inheritance pattern and management strategy has not been fully elucidated. Here, we review the contribution of LZTR1 in NS and describe a patient with a novel, likely pathogenic variant in LZTR1.

Case presentation

A female patient was diagnosed with clinical NS at 8 months of age. She presented in adulthood when a brain and spine MRI identified plexiform neurofibromas; however, she did not meet the clinical criteria for Neurofibromatosis type 1. No pathogenic variants were identified through molecular genetic analysis of NF1, SPRED1 and a multigene NS panel. Whole exome sequencing at age 23 identified a novel de novo likely pathogenic heterozygous variant in the LZTR1 gene denoted as c.743G>A (p.Gly248Glu). Serial MRIs have shown stable imaging findings and the patient is being followed clinically by cardiology, neurology and medical genetics.

Conclusions

We identified a novel mutation in the LZTR1 gene, not previously reported in association with NS. This report provides additional evidence to support for the assessment of schwannomatosis in patients with LZTR1-NS and may have overlap with Neurofibromatosis type 1.

Genetic conditions of short stature: A review of three classic examples

Noonan, Turner, and Prader-Willi syndromes are classical genetic disorders that are marked by short stature. Each disorder has been recognized for several decades and is backed by extensive published literature describing its features, genetic origins, and optimal treatment strategies. These disorders are accompanied by a multitude of comorbidities, including cardiovascular issues, endocrinopathies, and infertility. Diagnostic delays, syndrome-associated comorbidities, and inefficient communication among the members of a patient's health care team can affect a patient's well-being from birth through adulthood. Insufficient information is available to help patients and their multidisciplinary team of providers transition from pediatric to adult health care systems. The aim of this review is to summarize the clinical features and genetics associated with each syndrome, describe best practices for diagnosis and treatment, and emphasize the importance of multidisciplinary teams and appropriate care plans for the pediatric to adult health care transition.

Clinical report of a brain magnetic resonance imaging finding in Noonan syndrome

Noonan syndrome (NS) is an autosomal dominant disease caused by aberrant up-regulated signaling through RAS GTPase. It is characterized by facial dysmorphisms, short stature, congenital heart defects, malformations of rib cage bones, bleeding problems, learning difficulties, or mild intellectual disability. Additional intracranial findings in NS patients include tumors, midline anomalies, and malformations of cortical development. In this report, we present the case of a young female patient, with a known diagnosis of Noonan syndrome that in complete well being developed two brain lesions, in the right nucleus pallidus and in the left cerebellar hemisphere respectively, whose location and signal on MRI looked similar to neurofibromatosis type 1 unidentified bright objects (UBOs), and whose spectroscopic characteristics excluded neoplasms.