RARE DISEASE
X-linked hyper-IgM syndrome
X-linked hyper-IgM syndrome
X-linked hyper-IgM syndrome
Synonyms: HIGM1, Hyper-IgM syndrome due to CD40 ligand deficiency, Hyper-IgM syndrome due to CD40L deficiency, Hyper-IgM syndrome type 1, XHIGM
Synonyms: HIGM1, Hyper-IgM syndrome due to CD40 ligand deficiency, Hyper-IgM syndrome due to CD40L deficiency, Hyper-IgM syndrome type 1, XHIGM
Synonyms: HIGM1, Hyper-IgM syndrome due to CD40 ligand deficiency, Hyper-IgM syndrome due to CD40L deficiency, Hyper-IgM syndrome type 1, XHIGM
Drug discovery
1
drug
With orphan designation
Overview
X-linked hyper-IgM syndrome (XHIGM) is a rare, X-linked recessive immunodeficiency caused by CD40LG mutations, disrupting CD40L-CD40 interactions critical for B-cell class switching and T-cell activation. Affected males exhibit low IgG, IgA, and IgE with normal/elevated IgM, leading to severe bacterial (e.g., Pneumocystis jirovecii pneumonia) and opportunistic infections, chronic neutropenia, and complications like sclerosing cholangitis and lymphoma. Prognosis is poor without hematopoietic stem cell transplantation (HSCT) [1][2][6][15].
Categories: rare genetic diseases, rare immunological diseases, rare transplant-related disorders
Research Papers
189 drug discovery papers related to X-linked hyper-IgM syndrome, with 4 first-in-class and 0 next-in-class early-stage therapies forecasted to outperform the average preclinical success rate. Recent publications:
189 drug discovery papers related to X-linked hyper-IgM syndrome, with 4 first-in-class and 0 next-in-class early-stage therapies forecasted to outperform the average preclinical success rate. Recent publications:
2026-07-07 | Allogeneic hematopoietic cell transplantation with reduced-toxicity conditioning for X-linked hyper-IgM syndrome.
X-linked hyper-IgM syndrome (XHIGM) is an inborn error of immunity caused by variants in the CD40LG gene, leading to disrupted T-cell function and impaired immunoglobulin class-switch recombination. Supportive care alone is linked to unfavorable outcomes, necessitating allogeneic hematopoietic cell transplantation (HCT) as a curative option. Although myeloablative conditioning is recommended for HCT, concerns remain regarding its toxicity. We reviewed ten patients with XHIGM who underwent HCT using reduced-toxicity conditioning (RTC) at our institution between 2010 and 2024. All patients underwent HCT by 5 years of age (range: 2-5 years; median: 3 years). Donor sources included unrelated bone marrow, unrelated cord blood, and haploidentical-related donors. Conditioning primarily consisted of fludarabine and busulfan (target area under the curve: 60-65 mg/L·h), with low-dose total body irradiation (TBI) administered in five patients. Two patients experienced graft failure, requiring a second transplantation, and one died from post-transplant complications. The remaining nine patients survived. The 5-year overall survival rate was 88.9%; the 5-year graft-versus-host disease-free, relapse-free, and second transplantation-free survival rate was 67.5%. The addition of low-dose TBI to fludarabine/busulfan was associated with favorable long-term donor chimerism, although this finding should be considered hypothesis-generating. RTC may represent a feasible conditioning strategy for XHIGM.
2026-05-05 | Outcomes of Allogeneic Hematopoietic Stem Cell Transplantation in X-Linked Hyper IgM Syndrome: A Multicenter Chinese Cohort Study from CCBMT.
X-linked hyper-IgM syndrome (XHIGM) is a rare immunodeficiency for which allogeneic hematopoietic stem cell transplantation (HSCT) remains the only curative option, yet large pediatric Chinese datasets are scarce. We retrospectively analyzed 71 boys with genetically confirmed CD40L deficiency who underwent allogeneic HSCT between 2009 and 2020 at eight centers in China. Median age at HSCT was 3 yr (range, 0.6 to 17), with 74.6% transplanted before age 5. Donors were mismatched unrelated (42.3%), matched unrelated (33.8%), matched sibling (18.3%), and haploidentical (5.6%). Peripheral blood was the predominant stem cell source (67.6%), followed by cord blood (31.0%). Myeloablative conditioning was used in 95.8%. Median times to neutrophil and platelet engraftment were 12 and 14 d, respectively. Primary graft failure occurred in 5.6%. Acute GVHD developed in 60.6% (grade III to IV, 11.3%), and chronic GVHD in 25.4% (none-severe). Cytomegalovirus and EBV-DNAemia occurred in 56.3% and 39.4%, respectively; post-transplant lymphoproliferative disorder developed in 4.2%. Other complications included sinusoidal obstruction syndrome and hemorrhagic cystitis (7.0% each). At last follow-up, 9 patients (12.1%) had died, mainly from infections (8.5%). At a median follow-up of 7.8 yr, the estimated 10-yr overall, disease-free, and GVHD-free survival rates were 85.91%, 64.79%, and 77.14%, respectively. Survival was superior in younger patients, those with lower body weight, and well-matched related or unrelated donors. Immune reconstitution showed early NK recovery with progressive T and B cell restoration over 1 yr. These data support HSCT as effective long-term therapy for XHIGM and highlight benefits of early timing and optimal HLA matching.
2026-05-01 | Thriving Without Transplant: A Case of X-Linked Hyper-IgM Syndrome with Near-Normal Quality of Life on IVIG
Introduction Hyper-IgM syndrome (HIGM) is a rare primary immunodeficiency characterized by impaired immunoglobulin class-switch recombination, most commonly due to mutations in the CD40 ligand (CD40L) gene. Affected patients typically present in early childhood with recurrent sinopulmonary infections and are at risk for opportunistic infections, chronic lung disease, and immune dysregulation. Hematopoietic stem cell transplantation (HSCT) is considered curative but carries significant risks. Long-term outcomes with immunoglobulin replacement therapy alone in selected patients remain an area of clinical interest. Case Report We present a male patient with X-linked HIGM (CD40L Thr254Met mutation) diagnosed at age 6 years. He initially developed recurrent otitis media by 1 year of age, followed by recurrent bacterial pneumonias and chronic sinusitis. Notably, he had no history of opportunistic infections. Initial immunologic evaluation revealed elevated IgM (431 mg/dL), markedly low IgG and IgA, and undetectable IgE levels. He was started on intravenous immunoglobulin (IVIG) replacement therapy in 2011, resulting in significant clinical improvement and resolution of recurrent infections. He is currently 21 years of age, his immunoglobulin levels demonstrated therapeutic IgG (1,542 mg/dL), persistently low IgA (<5 mg/dL), and improved IgM (170 mg/dL). Over the subsequent years, he experienced only two mild, self-limited upper respiratory infections and was described by his family as healthier than most peers. He remained compliant with IVIG therapy (30 g every 3 weeks) and reported excellent quality of life. A minor gastrointestinal concern consisting of intermittent passage of small amounts of mucus-like stool with flatus was reported but was infrequent, nonprogressive, and without systemic symptoms. Physical examination was unremarkable. Given his stable clinical course, lack of opportunistic infections, and excellent response to IVIG, HSCT was previously discussed but deferred in favor of continued immunoglobulin replacement. Discussion This case highlights the potential for excellent long-term clinical stability in selected patients with X-linked HIGM managed with IVIG alone. While HSCT remains the definitive therapy, careful patient selection is critical, particularly in those with mild phenotypes and excellent infection control. This case supports an individualized approach to management, emphasizing quality of life, treatment response, and shared decision-making in rare primary immunodeficiencies.
2026-07-07 | Allogeneic hematopoietic cell transplantation with reduced-toxicity conditioning for X-linked hyper-IgM syndrome.
X-linked hyper-IgM syndrome (XHIGM) is an inborn error of immunity caused by variants in the CD40LG gene, leading to disrupted T-cell function and impaired immunoglobulin class-switch recombination. Supportive care alone is linked to unfavorable outcomes, necessitating allogeneic hematopoietic cell transplantation (HCT) as a curative option. Although myeloablative conditioning is recommended for HCT, concerns remain regarding its toxicity. We reviewed ten patients with XHIGM who underwent HCT using reduced-toxicity conditioning (RTC) at our institution between 2010 and 2024. All patients underwent HCT by 5 years of age (range: 2-5 years; median: 3 years). Donor sources included unrelated bone marrow, unrelated cord blood, and haploidentical-related donors. Conditioning primarily consisted of fludarabine and busulfan (target area under the curve: 60-65 mg/L·h), with low-dose total body irradiation (TBI) administered in five patients. Two patients experienced graft failure, requiring a second transplantation, and one died from post-transplant complications. The remaining nine patients survived. The 5-year overall survival rate was 88.9%; the 5-year graft-versus-host disease-free, relapse-free, and second transplantation-free survival rate was 67.5%. The addition of low-dose TBI to fludarabine/busulfan was associated with favorable long-term donor chimerism, although this finding should be considered hypothesis-generating. RTC may represent a feasible conditioning strategy for XHIGM.
2026-05-05 | Outcomes of Allogeneic Hematopoietic Stem Cell Transplantation in X-Linked Hyper IgM Syndrome: A Multicenter Chinese Cohort Study from CCBMT.
X-linked hyper-IgM syndrome (XHIGM) is a rare immunodeficiency for which allogeneic hematopoietic stem cell transplantation (HSCT) remains the only curative option, yet large pediatric Chinese datasets are scarce. We retrospectively analyzed 71 boys with genetically confirmed CD40L deficiency who underwent allogeneic HSCT between 2009 and 2020 at eight centers in China. Median age at HSCT was 3 yr (range, 0.6 to 17), with 74.6% transplanted before age 5. Donors were mismatched unrelated (42.3%), matched unrelated (33.8%), matched sibling (18.3%), and haploidentical (5.6%). Peripheral blood was the predominant stem cell source (67.6%), followed by cord blood (31.0%). Myeloablative conditioning was used in 95.8%. Median times to neutrophil and platelet engraftment were 12 and 14 d, respectively. Primary graft failure occurred in 5.6%. Acute GVHD developed in 60.6% (grade III to IV, 11.3%), and chronic GVHD in 25.4% (none-severe). Cytomegalovirus and EBV-DNAemia occurred in 56.3% and 39.4%, respectively; post-transplant lymphoproliferative disorder developed in 4.2%. Other complications included sinusoidal obstruction syndrome and hemorrhagic cystitis (7.0% each). At last follow-up, 9 patients (12.1%) had died, mainly from infections (8.5%). At a median follow-up of 7.8 yr, the estimated 10-yr overall, disease-free, and GVHD-free survival rates were 85.91%, 64.79%, and 77.14%, respectively. Survival was superior in younger patients, those with lower body weight, and well-matched related or unrelated donors. Immune reconstitution showed early NK recovery with progressive T and B cell restoration over 1 yr. These data support HSCT as effective long-term therapy for XHIGM and highlight benefits of early timing and optimal HLA matching.
2026-05-01 | Thriving Without Transplant: A Case of X-Linked Hyper-IgM Syndrome with Near-Normal Quality of Life on IVIG
Introduction Hyper-IgM syndrome (HIGM) is a rare primary immunodeficiency characterized by impaired immunoglobulin class-switch recombination, most commonly due to mutations in the CD40 ligand (CD40L) gene. Affected patients typically present in early childhood with recurrent sinopulmonary infections and are at risk for opportunistic infections, chronic lung disease, and immune dysregulation. Hematopoietic stem cell transplantation (HSCT) is considered curative but carries significant risks. Long-term outcomes with immunoglobulin replacement therapy alone in selected patients remain an area of clinical interest. Case Report We present a male patient with X-linked HIGM (CD40L Thr254Met mutation) diagnosed at age 6 years. He initially developed recurrent otitis media by 1 year of age, followed by recurrent bacterial pneumonias and chronic sinusitis. Notably, he had no history of opportunistic infections. Initial immunologic evaluation revealed elevated IgM (431 mg/dL), markedly low IgG and IgA, and undetectable IgE levels. He was started on intravenous immunoglobulin (IVIG) replacement therapy in 2011, resulting in significant clinical improvement and resolution of recurrent infections. He is currently 21 years of age, his immunoglobulin levels demonstrated therapeutic IgG (1,542 mg/dL), persistently low IgA (<5 mg/dL), and improved IgM (170 mg/dL). Over the subsequent years, he experienced only two mild, self-limited upper respiratory infections and was described by his family as healthier than most peers. He remained compliant with IVIG therapy (30 g every 3 weeks) and reported excellent quality of life. A minor gastrointestinal concern consisting of intermittent passage of small amounts of mucus-like stool with flatus was reported but was infrequent, nonprogressive, and without systemic symptoms. Physical examination was unremarkable. Given his stable clinical course, lack of opportunistic infections, and excellent response to IVIG, HSCT was previously discussed but deferred in favor of continued immunoglobulin replacement. Discussion This case highlights the potential for excellent long-term clinical stability in selected patients with X-linked HIGM managed with IVIG alone. While HSCT remains the definitive therapy, careful patient selection is critical, particularly in those with mild phenotypes and excellent infection control. This case supports an individualized approach to management, emphasizing quality of life, treatment response, and shared decision-making in rare primary immunodeficiencies.
Access all drug discovery articles and probability of success in trials forecasts:
Access all drug discovery articles and probability of success in trials forecasts:
Drug Discovery Landscape
1 orphan drug designation for X-linked hyper-IgM syndrome.
1 orphan drug designation for X-linked hyper-IgM syndrome.
Drug | Therapy type | Regulator | Orphan designation | Approval | Sponsor |
|---|---|---|---|---|---|
Autologous peripheral blood-derived CD4 T-cells CRISPR-edited at the CD40LG locus | gene editing enzymes | EMA | 2022-05-16 | — | Fondazione Telethon Ets |
Let's accelerate rare disease drug discovery
Let's accelerate drug discovery
Get access to Explority AI's forecasts to outperform average preclinical success rates. Whether you're expanding your R&D pipeline, evaluating a partnership, or simply have a question — we'd love to hear from you.