Von Recklinghausen neurofibromatosis and genetic linkage studies: clinical considerations.

For genetic linkage purposes, a subject at risk for Von Recklinghausen neurofibromatosis (VRNF) is one who has a first degree relative with independently documented VRNF. The presence of one or more of the designated criteria establishes the phenotypic diagnosis of VRNF in a subject at risk regardless of age. The absence of all of these criteria excludes the phenotypic diagnosis for all at risk subjects over five years of age. The absence of all the criteria in subjects at risk below five years of age or the presence of equivocal or merely suggestive findings neither excludes nor substantiates the phenotypic diagnosis of VRNF; rather, that subject should be removed from the preliminary scoring and analyses of the data.