Table 1.

National Institutes of Health diagnostic criteria for neurofibromatosis type 1 [26].

In an individual who does not have a parent diagnosed with NF1, two or more are required to make a diagnosis of NF1:

Pre-pubertal: ≥6 café-au-lait macules > 5 mm in diameter Post-pubertal: ≥6 café-au-lait macules > 15 mm in diameter

Axillary or inguinal freckling

≥2 neurofibromas of any type, OR ≥ 1 plexiform neurofibroma

Optic pathway glioma

≥2 Lisch nodules, OR ≥ 2 choroidal abnormalities

Presence of a distinctive osseous lesion: sphenoid dysplasia OR anterolateral bowing of the tibia OR pseudarthrosis of a long bone

Presence of a heterozygous pathogenic NF1 variant in apparently unaffected tissue (such as white blood cells), with a variant allele fraction of ≥50%

If an individual has a parent who meets the above diagnostic criteria, a diagnosis of NF1 may be made in that individual if one or more of the above criteria are present.