NF1 NM_000267.3:c.369C>G, Thr123=

Variant summary: The NF1 c.369C>G (p.Thr123Thr) variant involves the alteration of a non-conserved nucleotide, resulting in a synonymous change. One in silico tool predicts a damaging outcome for this variant. 4/5 splice prediction tools predict no significant impact on normal splicing. However, these predictions have yet to be confirmed by functional studies. This variant was found in 107/121302 control chromosomes (2 homozygotes), predominantly observed in the East Asian subpopulation at a frequency of 0.012034 (104/8642). This frequency is about 58 times the estimated maximal expected allele frequency of a pathogenic NF1 variant (0.0002084), suggesting this is likely a benign polymorphism found primarily in the populations of East Asian origin. The variant was reported in patients in the literature who also carry truncating NF1 mutations, further supporting the benign nature of the variant of interest. In addition, multiple clinical diagnostic laboratories/reputable databases classified this variant as likely benign/benign. Taken together, this variant is classified as benign.