Spinal neurofibromatosis with NF1 mutation in a classic neurofibromatosis type 1 family: A case report and literature review

Germline mutations in pediatric cancer cohort with mixed-ancestry Mexicans

BACKGROUND

Childhood cancer is one of the primary causes of disease-related death in 5- to 14-year-old children and currently no prevention strategies exist to reduce the incidence of this disease. Childhood cancer has a larger hereditary component compared with cancer in adults. Few genetic studies have been conducted on children with cancer. Additionally, Latin American populations are underrepresented in genomic studies compared with other populations. Therefore, the aim of this study is to analyze germline mutations in a group of mixed-ancestry Mexican pediatric patients with solid and hematological cancers.

METHODS

We analyzed genetic variants from 40 Mexican childhood cancer patients and their relatives. DNA from saliva or blood samples was used for whole-exome sequencing. All variants were identified following GATK best practices.

RESULTS

We found that six patients (15%) were carriers of germline mutations in CDKN2A, CHEK2, DICER1, FANCA, MSH6, MUTYH, NF1, and SBDS cancer predisposition genes, and additional new variants predicted to be deleterious by in silico algorithms. A population genetics analysis detected five components consistent with the demographic models assumed for modern mixed-ancestry Mexicans.

CONCLUSIONS

This report identifies potential genetic risk factors and provides a better understanding of the underlying mechanisms of childhood cancer in this population.

Case report: Bilateral spinal neurofibromatosis

Spinal neurofibromatosis (SNF) is a rare form of Neurofibromatosis in which neurofibromas exist bilaterally throughout all spinal roots. Despite previous attempts made to characterize and classify the disease as a separate clinical form of the disease, the low incidence rate of the disease and scarcity of previous reports calls for further studies and reports to elaborate this clinical entity. The patient in this report was a 36-year-old man presenting with lower limb weakness, unsteady gait, and paresthesia. The patient also presented with multiple cutaneous café-au-lait spots, cutaneous neurofibromas, and a large neurocutaneous neurofibroma of right facial nerve. Magnetic resonance imaging (MRI) of spine revealed bilateral spinal neurofibromas across all spinal cord roots. MRI study of head revealed no abnormalities in the brain and optic tract. The patient fulfilled both NIH criteria as well as revised criteria for NF1. Despite total spinal cord involvement, surgical intervention was withheld from the patient due to high propensity of recurrence as seen with previous attempts in removing peripheral neurofibromas, slow progression of symptoms, and lack of significant pain and impairment. SNF is often described as a form of disease with infrequent presentation of classical NF1 symptoms other than spinal tumors. The case presented here however, presented with several cutaneous neurofibromas and café-au-lait spots. Considering the positive outcome of surgical intervention in a few other reports, the decision to surgically intervene should be left to the clinical judgement of the participating surgeon, patient preference and socioeconomic background in a case-by-case manner.

A novel mutation of the NF1 gene in a Chinese family with neurofibromatosis type 1

BACKGROUND

Mutations in the neurofibromin 1 (NF1) gene are associated with clinical manifestations of neurofibromatosis type 1 (NF1).

OBJECTIVE

To clarify the relationship between NF1 variants and disease phenotype.

METHODS

Peripheral blood samples were collected from a patient and her relatives and genomic DNA was extracted for next-generation sequencing (NGS) to detect potential variants; the results were validated by Sanger sequencing.

RESULTS

A novel frameshift variant c.4508_c.4509delAT (p.Asn1503fsTer26) was detected in exon 34 of the NF1 gene in the patient and her daughter, but not in any other (healthy) family member. This c.4508_c.4509delAT (p.Asn1503fsTer26) frameshift variant of NF1 may underlie NF1 in this family.

CONCLUSIONS

This finding expands the spectrum of pathogenic mutations of the NF1 gene, which could aid genetic counseling and prenatal diagnosis.

Spinal neurofibromatosis with NF1 mutation in a classic neurofibromatosis type 1 family: A case report and literature review

Background

Spinal neurofibromatosis (SNF) is a related form of Neurofibromatosis type 1 (NF1) with a low incidence. Here, we report a SNF patient with NF1 (OMIM *613113) mutation in a classic NF1 family to enrich the case data.

Methods

We presented the clinical data of a 27‐year‐old female suffered from SNF. Two NF1 individuals (the mother and the brother) in the patient's family were also described. In the SNF patient, tumors in cervical were removed by surgical operation after the spinal MRI evaluation. Hematoxylin‐eosin staining and immunohistochemistry were performed to better characterize the excised tumors. NF1 exons of the patient and her NF1 families were further sequenced by the next‐generation sequencing technology.

Results

The patient developed irregular café‐au‐lait macules, multi‐subcutaneous nodules, recurrent numbness, and weakness of both lower extremities. Multiple neurofibromas were found in the whole spine by spinal MRI. Tumor‐like cells and hyperplasia of ganglion cells were found in the excised tissue by H&E staining and immunohistochemistry, respectively. One‐year follow‐up on the SNF patient showed that after the surgery lower limb pain, numbness and convulsion were completely relieved. A common germ‐line pathogenic mutation (NM_000267.3:c.1721 + 3A>G) was found in both the SNF patient and her classic NF1 families.

Conclusion

A case of SNF with classic NF1 mutation in a classic NF1 family was identified for the first time, indicating that SNF may share the same gene mutation with NF1, while the different manifestation of NF1 and SNF may be related to gene modification.