Mutational spectrum of NF1 gene in 24 unrelated Egyptian families with neurofibromatosis type 1.

BACKGROUND: Neurofibromatosis 1 (NF1; OMIM# 162200) is a common autosomal dominant genetic disease [incidence: ~1:3500]. In 95% of cases, clinical diagnosis of the disease is based on the presence of at least two of the seven National Institute of Health diagnostic criteria. The molecular pathology underlying this disorder entails mutation in the NF1 gene. The aim of this study was to investigate clinical and molecular characteristics of a cohort of Egyptian NF1 patients.

METHOD: This study included 35 clinically diagnosed NF1 patients descending from 25 unrelated families. Patients had ≥2 NIH diagnostic criteria. Examination of NF1 gene was done through direct cDNA sequencing of multiple overlapping fragments. This was supplemented by NF1 multiple ligation dependent probe amplification (MLPA) analysis of leucocytic DNA.

RESULTS: The clinical presentations encompassed, café-au-lait spots in 100% of probands, freckling (52%), neurofibromas (20%), Lisch nodules of the iris (12%), optic pathway glioma (8%), typical skeletal disorders (20%), and positive family history (32%). Mutations could be detected in 24 families (96%). Eight mutations (33%) were novel.

CONCLUSION: This study illustrates the underlying molecular pathology among Egyptian NF1 patients for the first time. It also reports on 8 novel mutation expanding pathogenic mutational spectra in the NF1 gene.