T-Cell Lymphopenia Detected by Newborn Screening in Two Siblings with an Xq13.1 Duplication.

Newborn screening for severe combined immunodeficiency has proven successful in identifying infants with T-cell deficiencies before they become severely ill. Additionally, the newborn screen can detect subtle early phenotypes that may become severe later in life. We present the case of siblings with features suggestive of T-cell lymphopenia identified as having low T-cell receptor excision circles counts by newborn screening. Expanded immune testing showed robust lymphocyte mitogen and antigen responses with normal vaccine responses and immunoglobulin levels for both boys over time. Genetic analysis revealed an Xq13.1 duplication in each child not found in the mother. The variant is downstream of the IL2RG gene with potential regulatory significance, suggesting a mechanism for the T-cell lymphopenia. The newborn screen provided these patients heightened surveillance and patient-specific management, including delayed live vaccines and Pneumocystis jiroveci pneumonia prophylaxis. Fortunately, the brothers have not suffered invasive or opportunistic infections and are well at ages 3 and 4 years. In this report, we illustrate the challenges of managing seemingly asymptomatic immunodeficient patients without a definitive genetic diagnosis and show how unbiased genetic analysis can expand understanding about primary immunodeficiency phenotypes.

Gene therapy for adenosine deaminase-deficient severe combined immune deficiency: clinical comparison of retroviral vectors and treatment plans.

We conducted a gene therapy trial in 10 patients with adenosine deaminase (ADA)-deficient severe combined immunodeficiency using 2 slightly different retroviral vectors for the transduction of patients' bone marrow CD34(+) cells. Four subjects were treated without pretransplantation cytoreduction and remained on ADA enzyme-replacement therapy (ERT) throughout the procedure. Only transient (months), low-level (< 0.01%) gene marking was observed in PBMCs of 2 older subjects (15 and 20 years of age), whereas some gene marking of PBMC has persisted for the past 9 years in 2 younger subjects (4 and 6 years). Six additional subjects were treated using the same gene transfer protocol, but after withdrawal of ERT and administration of low-dose busulfan (65-90 mg/m(2)). Three of these remain well, off ERT (5, 4, and 3 years postprocedure), with gene marking in PBMC of 1%-10%, and ADA enzyme expression in PBMC near or in the normal range. Two subjects were restarted on ERT because of poor gene marking and immune recovery, and one had a subsequent allogeneic hematopoietic stem cell transplantation. These studies directly demonstrate the importance of providing nonmyeloablative pretransplantation conditioning to achieve therapeutic benefits with gene therapy for ADA-deficient severe combined immunodeficiency.

Rare duplication or deletion of exons 6, 7 and 8 in CYBB leading to X-linked chronic granulomatous disease in two patients from different families.

Chronic granulomatous disease (CGD) is a rare congenital disorder in which phagocytes cannot generate superoxide (O(2)(-)) and other microbicidal oxidants due to mutations in one of the five components of the O(2)(-)-generating NADPH oxidase complex. The most common form is caused by mutations in CYBB on the X chromosome, encoding gp91phox, the enzymatic subunit of the phagocyte NADPH oxidase. Here, we report two rare cases of male X-linked CGD patients, one caused by a 5.7-kb duplication of a region containing CYBB exons 6 to 8 and the other caused by a deletion of this same region. We found both the duplication in patient 1 and the deletion in patient 2 to be bordered by a GT repeat. Indeed, in control DNA, the 3' part of CYBB intron 5 contains a GT repeat and the 5' part of intron 8 also contains such a repeat. Duplication of exons 6, 7 and 8 in patient 1 was probably caused by a non-homologous crossing over between the two GT repeats. The deletion found in patient 2 probably arose from a similar misalignment. The results found in these patients were confirmed by multiplex ligation-dependent probe amplification. The clinical profile of XCGD is severe in both patients.

Epstein-Barr virus-associated smooth muscle tumors in ataxia-telangiectasia: a case report and review.

Chromosomal breakage syndromes, including ataxia-telangiectasia (AT), are autosomal recessive disorders in which DNA repair mechanisms are defective resulting in chromosomal instability. Affected individuals are at high risk for developing malignancy because of the widespread resulting cellular effects. One such effect, severe immunosuppression, can permit virally mediated neoplasms to manifest, similar to those seen in acquired immunodeficiency syndrome (AIDS), congenital immune deficiency syndromes, and posttransplant populations. Epstein-Barr virus (EBV) is a common viral agent known to be associated with lymphoid, epithelial, and smooth muscle malignancies in such patients. Although smooth muscle tumors have been reported in patients with AT, their association with EBV has not been evaluated. We present a case of EBV-associated laryngeal leiomyosarcoma and jejunal cellular leiomyoma in a child with AT. This case suggests that the development of neoplasia in patients with chromosomal breakage syndromes may be related to the immunosuppressive consequences of these diseases, and searching for infectious causes (such as EBV) is important.