Editor—The diagnostic criteria for neurofibromatosis type 1 (NF1) was established in 1987 by the National Institutes of Health (NIH) in the consensus development conference and defined further in 1997 (table 1).1 2 The frequency of clinical findings in NF1 patients varies greatly between series, probably on account of ascertainment differences and population versus hospital based patient groups. In the present report, the clinical findings are derived from a Finnish population based study of NF. The clinical and in some cases risk haplotype analysis was extended to the first degree relatives of the patients.

The clinical assessment formed part of a population based study of neurofibromatosis in northern Finland in which 172 patients with NF1 or the segmental type of NF were examined by the author during the years 1989-1996 at the Department of Clinical Genetics, Oulu University Hospital, or at one of its four satellite clinics. Clinical evaluation of the patients included a review of their medical history, including hospital records, necropsy reports, and family histories. A detailed clinical examination was performed, followed by genetic counselling. A clinical assessment was made of cutaneous, neurological, ocular, orthopaedic, and cardiovascular manifestations. Endocrine, auditory, and dysmorphic findings were recorded systematically according to a modified examination schedule used by the NNFF (National Neurofibromatosis Foundation) International Database,3 and developmental and behavioural features and growth parameters were recorded. An ophthalmological or neuro-ophthalmological (n=123) examination and a CT or MRI scan of the brain (n=121) and MRI scan of the spine (n=77) were performed. In selected cases, the patients were seen by other specialists. The first degree relatives of the index cases were examined. The protocol was approved by the Ethics Committee of the Medical Faculty, University of Oulu.

All data were recorded …