Patients with neurofibromatosis type 1 (NF1) and type 1
NF1 deletions often exhibit more severe clinical manifestations than patients with intragenic
NF1 gene mutations, including facial dysmorphic features, overgrowth, severe global developmental delay, severe autistic symptoms and considerably reduced cognitive abilities, all of
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Patients with neurofibromatosis type 1 (NF1) and type 1
NF1 deletions often exhibit more severe clinical manifestations than patients with intragenic
NF1 gene mutations, including facial dysmorphic features, overgrowth, severe global developmental delay, severe autistic symptoms and considerably reduced cognitive abilities, all of which are detectable from a very young age. Type 1
NF1 deletions encompass 1.4 Mb and are associated with the loss of 14 protein-coding genes, including
NF1 and
SUZ12. Atypical
NF1 deletions, which do not encompass all 14 protein-coding genes located within the type 1
NF1 deletion region, have the potential to contribute to the delineation of the genotype/phenotype relationship in patients with
NF1 microdeletions. Here, we review all atypical
NF1 deletions reported to date as well as the clinical phenotype observed in the patients concerned. We compare these findings with those of a newly identified atypical
NF1 deletion of 698 kb which, in addition to the
NF1 gene, includes five genes located centromeric to
NF1. The atypical
NF1 deletion in this patient does not include the
SUZ12 gene but does encompass
CRLF3. Comparative analysis of such atypical
NF1 deletions suggests that
SUZ12 hemizygosity is likely to contribute significantly to the reduced cognitive abilities, severe global developmental delay and facial dysmorphisms observed in patients with type 1
NF1 deletions.
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