Successful unrelated cord blood transplant for complete IFN-γ receptor 2 deficiency

Hematopoietic Stem Cell Transplantation for Patients with Autosomal Recessive Complete INF-λ Receptor 2 Deficiency: Experience in Oman

Autosomal recessive complete INF-γ receptor-2 (IFN-γR2) deficiency is a rare, potentially fatal primary immune deficiency that predisposes to disseminated mycobacterial disease. Hematopoietic stem cell transplantation (HSCT) is currently the only curative treatment. Few patients have been reported so far. Here we report the outcomes of HSCT in 7 patients with IFNγ-R2 deficiency from 3 Omani families who underwent HSCT at Sultan Qaboos University Hospital in Oman. All patients were homozygous for the same mutation (c.-175_+102del) of INFGR2. Four patients underwent HLA-matched related donor (MRD) HSCT (3 siblings and 1 parent), and the other 3 underwent T cell-depleted (TCD) haploidentical HSCT from a family donor. The stem cell source was peripheral blood stem cells in 5 patients and bone marrow in 2 patients. Five patients received myeloablative conditioning, and 2 had reduced-intensity conditioning. The overall survival rate was 85.7%, and the event-free survival was 71.4%. One of the 7 patients died on day +31 with gram-negative sepsis, and the other 6 patients were cured from their original disease (median follow-up of 78.5 months). One patient had primary graft failure following a TCD-haploidentical transplantation and underwent successful retransplantation from another haploidentical relative. Three patients received a donor lymphocyte infusion for mixed chimerism. Our findings indicate that HSCT is curative for complete IFN-γR2 deficiency. In this cohort from Oman, 85.7% of the patients were cured with either an MRD or a TCD haploidentical transplantation. Genetic analysis at birth in children of high-risk couples permits early diagnosis, prevents the morbidity of BCG vaccination, and can enable safer and more successful transplantation outcomes.

Successful Matched Related Bone Marrow Transplantation in a Patient with Autosomal Dominant Interferon Gamma Receptor 1 Deficiency

This is a report of a successful bone marrow transplant in an IFN-γR1 patient with progressive mycobacterial infection.

PURPOSE

Hematopoietic cell transplant in patients with interferon gamma receptor deficiencies has been fraught with challenges, not the least of which is failure of engraftment and infectious complications.

METHODS

This is a report of a successful hematopoietic cell transplant in an actively infected patient of advanced age.

RESULTS

This case report shows successful engraftment and resolution of infection posttransplant using a matched related donor in a single institution.

CONCLUSION

A successful curative HCT despite persistent, disseminated, nontuberculous mycobacterial infection in a patient with AD-IFNγR1 suggests that this approach, while difficult, may be useful in other patients with otherwise refractory disease.

A purely quantitative form of partial recessive IFN-γR2 deficiency caused by mutations of the initiation or second codon

Mendelian susceptibility to mycobacterial disease (MSMD) is characterized by clinical disease caused by weakly virulent mycobacteria, such as environmental mycobacteria and Bacillus Calmette-Guérin vaccines, in otherwise healthy individuals. All known genetic etiologies disrupt interferon (IFN)-γ immunity. Germline bi-allelic mutations of IFNGR2 can underlie partial or complete forms of IFN-γ receptor 2 (IFN-γR2) deficiency. Patients with partial IFN-γR2 deficiency express a dysfunctional molecule on the cell surface. We studied three patients with MSMD from two unrelated kindreds from Turkey (P1, P2) and India (P3), by whole-exome sequencing. P1 and P2 are homozygous for a mutation of the initiation codon(c.1A>G) of IFNGR2, whereas P3 is homozygous for a mutation of the second codon (c.4delC). Overexpressed mutant alleles produce small amounts of full-length IFN-γR2 resulting in an impaired, but not abolished, response to IFN-γ. Moreover, SV40-fibroblasts of P1 and P2 responded weakly to IFN-γ, and Epstein Barr virus-transformed B cells had a barely detectable response to IFN-γ. Studies in patients' primary T cells and monocyte-derived macrophages yielded similar results. The residual expression of IFN-γR2 protein of normal molecular weight and function is due to the initiation of translation between the second and ninth non-AUG codons. We thus describe mutations of the first and second codons of IFNGR2, which define a new form of partial recessive IFN-γR2 deficiency. Residual levels of IFN-γ signaling were very low, accounting for the more severe clinical phenotype of these patients with residual expression levels of normally functional surface receptors than of patients with partial recessive IFN-γR2 deficiency due to surface-expressed dysfunctional receptors, whose residual levels of IFN-γ signaling were higher.

Mendelian susceptibility to mycobacterial disease: 2014-2018 update

Mendelian susceptibility to mycobacterial disease (MSMD) is caused by inborn errors of IFN-γ immunity. Since 1996, disease-causing mutations have been found in 11 genes, which, through allelic heterogeneity, underlie 21 different genetic disorders. We briefly review here progress in the study of molecular, cellular and clinical aspects of MSMD since the last comprehensive review published in 2014. Highlights include the discoveries of (1) a new genetic etiology, autosomal recessive signal peptide peptidase-like 2 A deficiency, (2) TYK2-deficient patients with a clinical phenotype of MSMD, (3) an allelic form of partial recessive IFN-γR2 deficiency, and (4) two forms of syndromic MSMD: RORγ/RORγT and JAK1 deficiencies. These recent findings illustrate how genetic and immunological studies of MSMD can shed a unique light onto the mechanisms of protective immunity to mycobacteria in humans.