ITPKB was first reported in relation to autosomal recessive ITPKB deficiency in 2020 (Almutairi A, et al., PMID: 31987846). One frameshift variant has been reported in one proband in one publication (PMIDs: 31987846). The proband was born to consanguineous parents and presented with failure to thrive, oral thrush, recurrent pneumonia, skin abscesses, anemia, leukopenia, neutropenia, thrombocytopenia, and profound CD3+ CD4+ and CD8+ cell lymphopenia, consistent with T-B+NK+ severe combined immunodeficiency. The parents and unaffected sibling were heterozygous for the same variant and none had a history of recurrent infections. CD3+, CD4+, CD8+, and CD19+ B-cell numbers were normal in the parents. To date, the only reported variant is a frameshift at the 3’ end of the gene that may escape nonsense mediated decay. In vitro functional studies showed that this variant caused reduced expression and absent kinase activity. The mechanism of pathogenicity appears to be loss of function. This gene-disease relationship is also supported by animal models, rescue studies, and functional assays (PMIDs: 31987846, 22981169, 14517551). In summary, there is limited evidence to support this gene-disease relationship. Although more evidence is needed to support a causal role, no convincing evidence has emerged that contradicts the gene-disease relationship. This classification was approved by the ClinGen SCID-CID GCEP on the meeting date [November 16, 2023] (SOP Version 9)].
The GenCC data are available free of restriction under a CC0 1.0 Universal (CC0 1.0) Public Domain Dedication. The GenCC requests that you give attribution to GenCC and the contributing sources whenever possible and appropriate. The accepted Flagship manuscript is now available from Genetics in Medicine (https://www.gimjournal.org/article/S1098-3600(22)00746-8/fulltext).
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