Phenotype-Genotype Correlation in Children with Neurofibromatosis Type 1.

Neurofibromatosis type 1 (NF1) is a common autosomal dominant disorder with an incidence of ∼1 in 4,000 live births. Neurofibromin, the gene product, is ubiquitously expressed at high levels in the nervous system and functions as a tumor suppressor. Haploinsufficiency of neurofibromin through mutation leads to an increased risk of developing benign and malignant tumors in affected individuals. Although NF1 has complete penetrance, it displays considerable inter- and intrafamilial variability in phenotypic expression which poses disease prediction and management problems. Some NF1 genotype-phenotype correlations have been described. To evaluate the genetic component of variable expressivity in NF1, we examined the phenotypic correlations between affected relatives in 52 NF1 patients from 45 families.