ClinVar

Description

The IFIH1 c.1641+1G>C variant was identified in the literature found to be associated with Type 1 Diabetes in a large case-control study (Nejentsev_2009_PMID:19264985). The variant was identified in dbSNP (ID: rs35337543), LOVD 3.0 (classified as likely benign and a VUS) and ClinVar (classified as benign by Prevention Genetics and Invitae, as uncertain significance by Center for Genomics, Ann and Robert H. Lurie Children's Hospital of Chicago and as likely pathogenic by CeGaT Praxis fuer Humangenetik Tuebingen). The variant was not identified in other databases. The variant was identified in control databases in 1888 of 281368 chromosomes (7 homozygous) at a frequency of 0.00671 increasing the likelihood this could be a low frequency benign variant (Genome Aggregation Database March 6, 2019, v2.1.1). The variant was observed in the following populations: European (non-Finnish) in 1379 of 128286 chromosomes (freq: 0.01075), Latino in 332 of 35158 chromosomes (freq: 0.009443), Other in 66 of 7164 chromosomes (freq: 0.009213), African in 70 of 24914 chromosomes (freq: 0.00281), Ashkenazi Jewish in 13 of 10352 chromosomes (freq: 0.001256), South Asian in 16 of 30490 chromosomes (freq: 0.000525), European (Finnish) in 11 of 25070 chromosomes (freq: 0.000439), and East Asian in 1 of 19934 chromosomes (freq: 0.00005). The c.1641+1G>C variant is predicted to cause abnormal splicing because the nucleotide substitution occurs in the invariant region of the splice consensus sequence. Further, functional analysis of IFIH1 RNA has demonstrated aberrant splicing of the IFIH1 transcript with the c.1641+1G>C variant (Downes_2010_PMID:20844740). However, exon skipping due to loss of the splice consensus sequence is predicted to preserve the reading frame. In summary, based on the above information this variant meets our laboratory's criteria to be classified as benign.