An epidemiological, clinical and genetic survey of neurofibromatosis type 1 in children under sixteen years of age.

AIM: To identify all cases of Neurofibromatosis type 1 in Northern Ireland under 16 years of age, document age, modes of presentation and any complications that occurred. METHODS: All cases of Neurofibromatosis type 1 in children less than 16 years of age were identified from the records in the Department of Medical Genetics. From the records and by direct contact with the patient's parents the relevant clinical information was obtained. RESULTS: Seventy-five children aged sixteen years or less were identified (prevalence of 17.6 per 100,000 (1 in 5681) of the population under 16 years of age). 45 (57%) had an affected first degree relative and 32 (43%) had no family history. 54 (72%) had at least one complication, 18 (24%) had 2; 9 (12%) had 3 and 3 (4%) had 4 complications. The most common complication was learning difficulties, which was seen in 37 (49.3%) cases. 11 (14.7%) patients had a malignancy; of whom 5 (6.7%) had an optic glioma (2 identified after diagnosis) and 3 (4%) had a CNS malignancy. CONCLUSION: Children with NF1 should be seen yearly by a health professional or team until after puberty and have a thorough clinical examination. The minimum prevalence is 1 in 5681 (17.6 per 100,000). We suggest a checklist is used to review nine important features; height, weight, head circumference, examination of the skin, blood pressure, ophthalmology examination (includes visual fields), examination of the spine, and for early/late puberty and consider referral to educational psychology. Educational authorities should identify all individuals with NF1 as they are at high risk of developing learning difficulties.