ClinVar

Description

The NM_000536.4:c.193G>T variant in RAG2 is a missense variant predicted to cause substitution of aspartic acid by tyrosine at amino acid 65 (p.Asp74Tyr). The variant has been reported in one individual with SCID. The individual was homozygous of this variant (PM3_Supporting, PMID 21624848). The individual had a T-B-NK+ lymphocyte profile and showed reduced T-cell proliferation under PHA stimulation, which supports a diagnosis of leaky/atypical SCID (PP4, PMID 21624848). The highest population minor allele frequency of this variant in gnomAD v2.1.1 is 0.000008791 (1/113758 alleles) in the European (non-Finnish) population, which is lower than the SCID-VCEP threshold (<0.0000588) for PM2_Supporting. No homozygous individual has been observed in the gnomAD v2.1.1 (PM2_Supporting). This variant resides within the core domain (amino acids 1-383) of RAG2, defined as a critical functional domain by the ClinGen SCID VCEP. (PM1_Supporting). An in vitro recombination activity assay shows that the relevant activity of the p.D65Y variant compared to wildtype RAG2 is 6.8%, which is below the threshold (<25%) established by the SCID VCEP for PS3_Moderate (PS3_Moderate, PMID 29772310). In summary, this variant meets the criteria to be classified as likely pathogenic for autosomal recessive recombinase activating gene 2 deficiency based on the ACMG/AMP criteria applied, as specified by the ClinGen SCID VCEP. Criteria applied: PP4, PM3_Supporting, PM2_Supporting, PM1_Supporting, and PS3_Moderate (VCEP specifications version 1.0).