Dear Colleague,
I met in consultation the child Gaston Rochon, born on 11/11/2018, for a genetic assessment of Neurofibromatosis type 1. Gaston has been known to the pediatric hematology service for a few months for the discovery of a glioma of the right optic nerve in the context of NF1. 
In terms of family history, Gaston is the 3rd child of his mother. He was born to non-related parents, his mother being of Swiss origin and his father of French origin. There is no longer any contact with Gaston's father. The mother describes that he would have probable numerous café-au-lait spots. He has not had any other health complications to her knowledge, notably no glioma of the optic pathways or tumors. No known cognitive disorders. 
The mother, Romaine Rochon born on 21/10/1990, measures about 1.65 m. Mrs. Rochon would present a spot on her left thigh and no other spots. Therefore, there is no evidence for her to be affected by neurofibromatosis type 1. 
From a previous union of the mother, Gaston has 2 half-sisters who do not present any café-au-lait spots. 
Regarding Gaston, the pregnancy was marked by diabetes treated with apparently good control during pregnancy. The ultrasounds were reportedly unremarkable. Gaston was born at 36 GA by cesarean section, macrosomic with a birth weight of 3950 g (99th p), a birth height of 52.5 cm (99th p), and a birth head circumference of 35.5 cm (94th p). 
Apgar 7-9 at birth, requiring transient ventilation. 
Regarding neurofibromatosis type 1, numerous café-au-lait spots appeared around 2 to 3 months of life. The diagnosis of Neurofibromatosis type 1 seems to have been made much later. Gaston is also followed by Dr. Descoteaux, a child psychiatrist, due to ADHD. 
Gaston is progressing in terms of psychomotor skills and language as well. 
On clinical examination today at the age of 4: weight = 13 kg (between the 10th and 25th percentile), height = 0.95 m (-0.5 SD), HC = 51 cm (average). I observe numerous café-au-lait spots in the context of his neurofibromatosis type 1. No visible neurofibromas today. Gaston is quite well in interaction, cooperating during the clinical examination, smiling. Tandem walking is still hesitant. He presents some pronunciation difficulties but understands simple instructions well. Bilateral symmetrical reflexes are slightly brisk, without spasticity or pyramidal syndrome. 
Neurofibromatosis type 1 (NF1) or Von Recklinghausen disease is a condition characterized by café-au-lait spots on the skin and tumors located along the nerves, called neurofibromas. Depending on the size, number, and location of these neurofibromas, complications may arise. It is one of the most common genetic diseases. Its manifestations are extremely variable from one patient to another, ranging from minor forms that may almost go unnoticed to severe forms. The most commonly encountered manifestations are cutaneous and neurological, but other organs may also be affected such as the eye and bones. 
Hypertension is more common than in the general population, as well as certain cancers. 
Neurofibromatosis type 1 is a genetic disease. The responsible gene, named NF1, is located on chromosome 17. The NF1 gene is a tumor suppressor gene that no longer functions due to mutation. It controls the production of a protein: neurofibromin. In the absence of this protein, benign tumors most often develop. 
Neurofibromatosis type 1 is an autosomal dominant disease, meaning it can be transmitted from generation to generation. Rodrigo will have a 50% risk of transmitting the disease to his children, regardless of their sex, with each pregnancy. 
Moreover, NF1 is a disease with very variable expressivity, meaning that clinical manifestations are extremely different from one patient to another, particularly in terms of severity. 
Penetrance is complete, so all individuals carrying the mutated gene manifest the disease, the constant manifestation being the presence of café-au-lait spots.
In summary, Gaston, 4 years old, presents a certain neurofibromatosis type 1 clinically as he presents:
- more than 6 café-au-lait spots with a diameter greater than 0.6 cm
- and a glioma of the optic nerve.
It is likely that his father is also affected.
From a genetic perspective, Gaston has been sampled today to search for the pathogenic variant of the NF1 gene responsible for the pathology in him with the informed and signed consent of his mother. The results will be available in several months, at least 6 months, and I will see Gaston again in consultation with these results. I remain available in the meantime for any questions.
Best regards,