Research on Genetic Reversion in Primary Immunondefiriency

我们已经发现了两个新的原发免疫缺陷的遗传逆转病例，包括白细胞黏附缺陷1型(LAD-1)和X连锁严重联合免疫缺陷(XSCID)1。LAD-1是一种由ITGB2(CD18)基因突变引起的常染色体隐性遗传病，其特征是反复发生严重感染、脓液形成障碍和创面愈合缺陷。我们描述了一例严重表型LAD-1呈现体细胞嵌合体的罕见病例。患者是一个复合杂合子，携带两种不同的移码突变，这两种突变使蛋白表达消失。然而，CD18在一小部分T细胞中被检测到，但在粒细胞、单核细胞、B细胞和NK细胞中未被检测到。T细胞不是母系来源，缺乏父系突变，在体内表现出选择性优势。对分选的CD18+细胞进行的分子分析表明，它们来自携带T细胞受体VB22的单个CD84 T细胞。这些发现提示t…更多的体内自发逆转是导致我们患者的体细胞嵌合体的原因。(血液2007)2)XSCID是由细胞因子受体的共同伽马链(γc)突变引起的，通常的特征是T细胞和自然杀伤(NK)细胞的缺失以及B细胞的存在。在此，我们报告一例XSCID的非典型病例，表现为自体T和NK细胞和Omenn综合征样表现，包括红皮病、淋巴结病、肝脾肿大、嗜酸性粒细胞增多症、血清免疫球蛋白G降低、血清免疫球蛋白E升高和T细胞活化。患者携带剪接点突变(IVS1+5G&gt；A)，导致大部分基因错误剪接，但产生少量正常剪接转录本，导致残留的γc表达和T细胞和NK细胞的发育。皮肤活检标本显示大量突变型T细胞。这些T细胞被发现具有第二位点突变，位于IVS1+5G&gt；A激活的隐蔽供体部位的+1位置，并导致完全恢复正确的剪接。这些发现表明，XSCID的临床谱系相当广泛，包括类似Omenn综合征的非典型病例，并强调了突变嵌合体作为可变表型表达的可能原因的重要性。(提交稿件)除了临床研究，我们还构建了表达逆转突变的逆转录病毒载体。这些载体将在未来的实验中用于评估体外诱导基因逆转的条件。较少

We have identified two novel cases of genetic reversion in primary immunodeficiency including leukocyte adhesion deficiency type 1 (LAD-1) and X-linked severe combined immunodeficiency (XSCID).1) LAD-1 is an autosomal recessive disorder caused by mutations in the ITGB2 (CD18) gene, and characterized by recurrent severe infections, impaired pus formation, and defective wound healing. We describe an unusual case of severe phenotypic LAD-1 presenting somatic mosaicism. The patient is a compound heterozygote bearing two different frameshift mutations which abrogate protein expression. CD 18 expression was, however, detected in a small proportion of T cells, but was undetectable in granulocytes, monocytes, B cells, and NK cells. The T cells were not of maternal origin, lacked the paternal mutation, and showed a selective advantage in vivo. Molecular analysis using sorted CD18+ cells revealed them to be derived from a single CD84 T cell carrying T-cell receptor VB22. These findings suggest t … More hat spontaneous in vivo reversion was responsible for the somatic mosaicism in our patient. (Blood 2007)2) XSCID is caused by mutations of the common gamma chain (γc) of cytokine receptors and usually characterized by the absence of T and natural killer (NK) cells and the presence of B Cells. Here, we report an atypical case of XSCID presenting with autologous T and NK cells and Omenn syndrome-like manifestations including erythroderma, lymphadenopathy, hepatosplenomegaly, eosinophilia, low serum IgG, elevated serum IgE, and the presence of activated T cells. The patient carried a splice-site mutation (IVS 1+5G>A) that caused most of the mRNA to be incorrectly spliced but produced normally spliced transcript in lesser amount, leading to residual γc expression and development of T and NK cells. The skin biopsy specimen showed massive infiltration of revertant T cells. Those T cells were found to have a second-site mutation that was located at position +1 of the cryptic donor site activated by the IVS1+5G>A, and to result in complete restoration of correct splicing. These findings suggest that the clinical spectrum of XSCID is quite broad and includes atypical cases mimicking Omenn syndrome, and highlight the importance of revertant mosaicism as a possible cause for variable phenotypic expression. (manuscript in submission)In addition to the clinical researches, we have constructed retroviral vectors expressing reversion mutations. These vectors will be used to evaluate conditions of induction of gene reversion in vitro in future experiments. Less