Table 2.

Genomic findings

Gene	Genomic location	HGVS cDNA	HGVS protein	Zygosity	Parent of origin	Variant interpretation
CECR1	Chr 22: 17207277 (GRCh38) Chr 22: 17688167 (GRCh37)	NM_017424 c.336C>G NM_001282227 c.210C>G	p.His112Gln	Heterozygous	Father	Pathogenic
CECR1	Chr 22: CECR1 deletion, ∼2 kb spanning exon 7; breakpoints unknown	NM_001282227 c.956-1113 del	p.Asp319GlyfsTer6	Heterozygous	Mother	Pathogenic

Variant interpretation: ADA2 deficiency is an autosomal recessive condition caused by biallelic loss-of-function mutations in the CECR1 gene. The His112Gln variant was reported previously in a patient with ADA2 deficiency (Navon Elkan et al. 2014). The CECR1 exon 7 deletion causes a frameshift mutation with premature translational termination. The proband is a compound heterozygote for the paternal and maternal CECR1 mutant alleles and has minimal circulating ADA2 activity. Hence, both mutations are pathogenic.