Neurofibromatosis 1 prevalence in children aged 9-11 years, Pinar del Río Province, Cuba.

INTRODUCTION Neurofibromatosis 1 is one of the most common heritable genetic disorders in humans. It is characterized by formation of neurofibromas, with marked variability in expression. Half the cases are due to autosomal dominant inheritance; the rest arise from de novo mutations. Prevalence varies by population, and prevalence in Cuba is unknown. OBJECTIVE Determine the prevalence of neurofibromatosis 1 in a population of Cuban children aged 9-11 years old in Pinar del Río Province, Cuba. METHODS A descriptive cross-sectional study was carried out in Pinar del Río Province in 2004, in which 19,392 children were assessed for neurofibromatosis 1. The study was conducted in two phases: the first, a survey of the entire population aged 9-11 years by genetic counselors in the province's schools; the second, assessment by clinical geneticists of children who met criteria for referral to the Provincial Medical Genetics Center. Neurofibromatosis 1 cases and first-degree relatives were examined to identify the origin of the mutation (de novo or inherited). Neurofibromatosis 1 prevalence was calculated, as well as history of a first-degree relative with the disease and frequency of several principal clinical signs-café au lait spots, freckles in places unexposed to sunlight, presence of neurofibromas, Lisch nodules and characteristic bone lesions. RESULTS Of the eligible population, 99.3% was screened (10,034 boys and 9358 girls). Active case finding resulted in referral of 200 children to medical geneticists and the disease was confirmed in 17, for a prevalence of one case per 1141 children aged 9-11 years old. Café au lait spots were the most frequent sign (100%), followed by freckles in areas unexposed to sunlight (82.4%) and characteristic bone lesions (41.2%). Only 4 of the 17 cases were previously being treated for the disease. CONCLUSIONS Neurofibromatosis 1 has high prevalence in the group studied in Pinar del Rio Province and most cases are not detected in primary health care settings.