Morton J. Cowan

Newborn Screening for Severe Combined Immunodeficiency in 11 Screening Programs in the United States

IMPORTANCE Newborn screening for severe combined immunodeficiency (SCID) using assays to detect T-cell receptor excision circles (TRECs) began in Wisconsin in 2008, and SCID was added to the national recommended uniform panel for newborn screened disorders in 2010. Currently 23 states, the District of Columbia, and the Navajo Nation conduct population-wide newborn screening for SCID. The incidence of SCID is estimated at 1 in 100,000 births. OBJECTIVES To present data from a spectrum of SCID newborn screening programs, establish population-based incidence for SCID and other conditions with T-cell lymphopenia, and document early institution of effective treatments. DESIGN Epidemiological and retrospective observational study. SETTING Representatives in states conducting SCID newborn screening were invited to submit their SCID screening algorithms, test performance data, and deidentified clinical and laboratory information regarding infants screened and cases with nonnormal results. Infants born from the start of each participating program from January 2008 through the most recent evaluable date prior to July 2013 were included. Representatives from 10 states plus the Navajo Area Indian Health Service contributed data from 3,030,083 newborns screened with a TREC test. MAIN OUTCOMES AND MEASURES Infants with SCID and other diagnoses of T-cell lymphopenia were classified. Incidence and, where possible, etiologies were determined. Interventions and survival were tracked. RESULTS Screening detected 52 cases of typical SCID, leaky SCID, and Omenn syndrome, affecting 1 in 58,000 infants (95% CI, 1/46,000-1/80,000). Survival of SCID-affected infants through their diagnosis and immune reconstitution was 87% (45/52), 92% (45/49) for infants who received transplantation, enzyme replacement, and/or gene therapy. Additional interventions for SCID and non-SCID T-cell lymphopenia included immunoglobulin infusions, preventive antibiotics, and avoidance of live vaccines. Variations in definitions and follow-up practices influenced the rates of detection of non-SCID T-cell lymphopenia. CONCLUSIONS AND RELEVANCE Newborn screening in 11 programs in the United States identified SCID in 1 in 58,000 infants, with high survival. The usefulness of detection of non-SCID T-cell lymphopenias by the same screening remains to be determined.

Transplantation Outcomes for Severe Combined Immunodeficiency, 2000–2009

BACKGROUND The Primary Immune Deficiency Treatment Consortium was formed to analyze the results of hematopoietic-cell transplantation in children with severe combined immunodeficiency (SCID) and other primary immunodeficiencies. Factors associated with a good transplantation outcome need to be identified in order to design safer and more effective curative therapy, particularly for children with SCID diagnosed at birth. METHODS We collected data retrospectively from 240 infants with SCID who had received transplants at 25 centers during a 10-year period (2000 through 2009). RESULTS Survival at 5 years, freedom from immunoglobulin substitution, and CD3+ T-cell and IgA recovery were more likely among recipients of grafts from matched sibling donors than among recipients of grafts from alternative donors. However, the survival rate was high regardless of donor type among infants who received transplants at 3.5 months of age or younger (94%) and among older infants without prior infection (90%) or with infection that had resolved (82%). Among actively infected infants without a matched sibling donor, survival was best among recipients of haploidentical T-cell-depleted transplants in the absence of any pretransplantation conditioning. Among survivors, reduced-intensity or myeloablative pretransplantation conditioning was associated with an increased likelihood of a CD3+ T-cell count of more than 1000 per cubic millimeter, freedom from immunoglobulin substitution, and IgA recovery but did not significantly affect CD4+ T-cell recovery or recovery of phytohemagglutinin-induced T-cell proliferation. The genetic subtype of SCID affected the quality of CD3+ T-cell recovery but not survival. CONCLUSIONS Transplants from donors other than matched siblings were associated with excellent survival among infants with SCID identified before the onset of infection. All available graft sources are expected to lead to excellent survival among asymptomatic infants. (Funded by the National Institute of Allergy and Infectious Diseases and others.).

X-linked lymphoproliferative disease due to SAP/SH2D1A deficiency: a multicenter study on the manifestations, management and outcome of the disease

X-linked lymphoproliferative disease (XLP1) is a rare immunodeficiency characterized by severe immune dysregulation and caused by mutations in the SH2D1A/SAP gene. Clinical manifestations are varied and include hemophagocytic lymphohistiocytosis (HLH), lymphoma and dysgammaglobulinemia, often triggered by Epstein-Barr virus infection. Historical data published before improved treatment regimens shows very poor outcome. We describe a large cohort of 91 genetically defined XLP1 patients collected from centers worldwide and report characteristics and outcome data for 43 patients receiving hematopoietic stem cell transplant (HSCT) and 48 untransplanted patients. The advent of better treatment strategies for HLH and malignancy has greatly reduced mortality for these patients, but HLH still remains the most severe feature of XLP1. Survival after allogeneic HSCT is 81.4% with good immune reconstitution in the large majority of patients and little evidence of posttransplant lymphoproliferative disease. However, survival falls to 50% in patients with HLH as a feature of disease. Untransplanted patients have an overall survival of 62.5% with the majority on immunoglobulin replacement therapy, but the outcome for those untransplanted after HLH is extremely poor (18.8%). HSCT should be undertaken in all patients with HLH, because outcome without transplant is extremely poor. The outcome of HSCT for other manifestations of XLP1 is very good, and if HSCT is not undertaken immediately, patients must be monitored closely for evidence of disease progression.

The graft-versus-leukemia effect using matched unrelated donors is not superior to HLA-identical siblings for hematopoietic stem cell transplantation.

Do some patients benefit from an unrelated donor (URD) transplant because of a stronger graft-versus-leukemia (GVL) effect? We analyzed 4099 patients with acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), and chronic myeloid leukemia (CML) undergoing a myeloablative allogeneic hematopoietic cell transplantation (HCT) from an URD (8/8 human leukocyte antigen [HLA]-matched, n=941) or HLA-identical sibling donor (n=3158) between 1995 and 2004 reported to the CIBMTR. In the Cox regression model, acute and chronic GVHD were added as time-dependent variables. In multivariate analysis, URD transplant recipients had a higher risk for transplantation-related mortality (TRM; relative risk [RR], 2.76; P< .001) and relapse (RR, 1.50; P< .002) in patients with AML, but not ALL or CML. Chronic GVHD was associated with a lower relapse risk in all diagnoses. Leukemia-free survival (LFS) was decreased in patients with AML without acute GVHD receiving a URD transplant (RR, 2.02; P< .001) but was comparable to those receiving HLA-identical sibling transplants in patients with ALL and CML. In patients without GVHD, multivariate analysis showed similar risk of relapse but decreased LFS for URD transplants for all 3 diagnoses. In conclusion, risk of relapse was the same (ALL, CML) or worse (AML) in URD transplant recipients compared with HLA-identical sibling transplant recipients, suggesting a similar GVL effect.

Acquired immune dysfunction in homosexual men: immunologic profiles.

Homosexual men with Kaposi sarcoma, lymphadenopathy syndrome, opportunistic infection, and nonhomosexual traditional Kaposi sarcoma were evaluated for B cell, T cell, and complement immunity and compared to normal controls and homosexual controls. No significant immunologic abnormalities were found in the traditional Kaposi group. All homosexual groups, including the homosexual controls, had a significant decrease in the helper/suppressor cell ratio. Functional abnormalities of T-cell immunity were observed in the homosexual Kaposi sarcoma, lymphadenopathy syndrome, and opportunistic infection groups. Significant elevations of IgG, IgM, IgA, and IgE were found in the lymphadenopathy group, while only IgG and IgA were elevated in the Kaposi sarcoma group. C3, C4, and immune complexes were normal, while total hemolytic complement activity was increased in the Kaposi sarcoma and lymphadenopathy syndrome groups.

A Founder Mutation in Artemis, an SNM1-Like Protein, Causes SCID in Athabascan-Speaking Native Americans

Athabascan SCID (SCIDA) is an autosomal recessive disorder found among Athabascan-speaking Native Americans and is manifested by the absence of both T and B cells (T−B−NK+ SCID). We previously mapped the SCIDA gene to a 6.5-cM interval on chromosome 10p. SCIDA fibroblasts were found to have defective coding joint and reduced, but precise signal joint formation during V(D)J recombination. After excluding potential candidate genes, we conducted a combined positional candidate and positional cloning approach leading to the identification of nine novel transcripts in the refined SCIDA region. One of the transcripts showed significant homology with the mouse and yeast SNM1/PSO2 and was recently reported (Artemis) to be responsible for another T−B−NK+ SCID condition (radiation sensitive SCID) in 13 patients of primarily European origin. In our evaluation of this gene, we have identified a unique nonsense mutation in 21 SCIDA patients that is closely correlated to the founder haplotypes that we had previously identified. This nonsense founder mutation results in the truncation of the deduced protein product. The wild-type construct of the primary transcript can effectively complement the defective coding joint and reduced signal joint formation in SCIDA fibroblasts. The above results indicate that this SNM1-like gene (Artemis) is the gene responsible for SCIDA. We also discovered three additional alternative exons and detected at least six alternatively spliced SCIDA variants (SCIDA-V1, 2, 3, 4, 5, and 6) coexisting with the primary transcript in trace amounts. Finally, we found that the SCIDA primary transcript (Artemis) encodes a nuclear protein.

Long-term outcome and lineage-specific chimerism in 194 patients with Wiskott-Aldrich syndrome treated by hematopoietic cell transplantation in the period 1980-2009: an international collaborative study.

In this retrospective collaborative study, we have analyzed long-term outcome and donor cell engraftment in 194 patients with Wiskott-Aldrich syndrome (WAS) who have been treated by hematopoietic cell transplantation (HCT) in the period 1980- 2009. Overall survival was 84.0% and was even higher (89.1% 5-year survival) for those who received HCT since the year 2000, reflecting recent improvement of outcome after transplantation from mismatched family donors and for patients who received HCT from an unrelated donor at older than 5 years. Patients who went to transplantation in better clinical conditions had a lower rate of post-HCT complications. Retrospective analysis of lineage-specific donor cell engraftment showed that stable full donor chimerism was attained by 72.3% of the patients who survived for at least 1 year after HCT. Mixed chimerism was associated with an increased risk of incomplete reconstitution of lymphocyte count and post-HCT autoimmunity, and myeloid donor cell chimerism < 50% was associated with persistent thrombocytopenia. These observations indicate continuous improvement of outcome after HCT for WAS and may have important implications for the development of novel protocols aiming to obtain full correction of the disease and reduce post-HCT complications.

Newborn screening for severe combined immunodeficiency and T-cell lymphopenia in California: Results of the first 2 years

BACKGROUND Assay of T-cell receptor excision circles (TRECs) in dried blood spots obtained at birth permits population-based newborn screening (NBS) for severe combined immunodeficiency (SCID). OBJECTIVE We sought to report the first 2 years of TREC NBS in California. METHODS Since August 2010, California has conducted SCID NBS. A high-throughput TREC quantitative PCR assay with DNA isolated from routine dried blood spots was developed. Samples with initial low TREC numbers had repeat DNA isolation with quantitative PCR for TRECs and a genomic control, and immunophenotyping was performed within the screening program for infants with incomplete or abnormal results. Outcomes were tracked. RESULTS Of 993,724 infants screened, 50 (1/19,900 [0.005%]) had significant T-cell lymphopenia. Fifteen (1/66,250) required hematopoietic cell or thymus transplantation or gene therapy; these infants had typical SCID (n = 11), leaky SCID or Omenn syndrome (n = 3), or complete DiGeorge syndrome (n = 1). Survival to date in this group is 93%. Other T-cell lymphopenic infants had variant SCID or combined immunodeficiency (n = 6), genetic syndromes associated with T-cell impairment (n = 12), secondary T-cell lymphopenia (n = 9), or preterm birth (n = 8). All T-cell lymphopenic infants avoided live vaccines and received appropriate interventions to prevent infections. TREC test specificity was excellent: only 0.08% of infants required a second test, and 0.016% required lymphocyte phenotyping by using flow cytometry. CONCLUSIONS TREC NBS in California has achieved early diagnosis of SCID and other conditions with T-cell lymphopenia, facilitating management and optimizing outcomes. Furthermore, NBS has revealed the incidence, causes, and follow-up of T-cell lymphopenia in a large diverse population.

Establishing diagnostic criteria for severe combined immunodeficiency disease (SCID), leaky SCID, and Omenn syndrome: The Primary Immune Deficiency Treatment Consortium experience

BACKGROUND The approach to the diagnosis of severe combined immunodeficiency disease (SCID) and related disorders varies among institutions and countries. OBJECTIVES The Primary Immune Deficiency Treatment Consortium attempted to develop a uniform set of criteria for diagnosing SCID and related disorders and has evaluated the results as part of a retrospective study of SCID in North America. METHODS Clinical records from 2000 through 2009 at 27 centers in North America were collected on 332 children treated with hematopoietic stem cell transplantation (HCT), enzyme replacement therapy, or gene therapy for SCID and related disorders. Eligibility for inclusion in the study and classification into disease groups were established by using set criteria and applied by an expert review group. RESULTS Two hundred eighty-five (86%) of the patients were determined to be eligible, and 47 (14%) were not eligible. Of the 285 eligible patients, 84% were classified as having typical SCID; 13% were classified as having leaky SCID, Omenn syndrome, or reticular dysgenesis; and 3% had a history of enzyme replacement or gene therapy. Detection of a genotype predicting an SCID phenotype was accepted for eligibility. Reasons for noneligibility were failure to demonstrate either impaired lymphocyte proliferation or maternal T-cell engraftment. Overall (n = 332) rates of testing were as follows: proliferation to PHA, 77%; maternal engraftment, 35%; and genotype, 79% (mutation identified in 62%). CONCLUSION Lack of complete laboratory evaluation of patients before HCT presents a significant barrier to definitive diagnosis of SCID and related disorders and prevented inclusion of subjects in our observational HCT study. This lesson is critical for patient care, as well as the design of future prospective treatment studies for such children because a well-defined and consistent study population is important for precision in outcomes analysis.

Wiskott-Aldrich Syndrome: Diagnosis, Clinical and Laboratory Manifestations, and Treatment

Wiskott-Aldrich syndrome (WAS) is a rare X-linked immunodeficiency disorder that has a variable clinical phenotype that correlates with the type of mutation in WASP, the gene encoding the WAS protein (WASP). WASP is a key regulator of actin polymerization in hematopoietic cells and has well-defined domains that are involved in signaling, cell locomotion, and immune synapse formation. Classic WAS often results from mutations that cause the absence of WASP expression, associated with thrombocytopenia with small platelets, sinopulmonary infections, and eczema in young males. Other phenotypes associated with expression of mutated WASP are X-linked thrombocytopenia and neutropenia. To date, the only curative therapy for WAS is hematopoietic cell transplantation (HCT) although gene therapy for WAS is under study. At least 2 retrospective studies of HCT for WAS have indicated that although HLA-matched sibling donors have the best outcomes (81% to 88%), when such a donor is not available, a matched unrelated donor should be considered (71% event free survival), although results are best in patients age < 5 years. Whereas most of the experience to date in Asia, Europe, and North America has been with myeloablative conditioning regimens, more recently, reduced-intensity conditioning (RIC) regimens also have been used with success. The issue of whether mixed chimerism post-HCT (which has a higher incidence in RIC transplantation) is associated with increased autoimmune manifestations in patients with WAS remains to be resolved.