The severity of the hemolytic disease of the fetus and newborn (HDFN) due to Jr^a mismatch ranges from no symptoms to severe anemia that requires intrauterine and exchange transfusions. We encountered a newborn, born to a healthy mother having anti-Jr^a at 38 weeks of pregnancy, who had moderate anemia, a positive direct antiglobulin test (DAT) result, no increased erythropoiesis, and no jaundice at birth. Flow cytometry revealed that the Jr^a antigen of red cells in the infant was nearly negative at birth, biphasic at 5 weeks, and lowly expressed at 7 months of life. We searched online for previous case reports on HDFN due to Jr^a incompatibility. Among 63 reported cases, excluding 25 cases, 38 were included with the present case for analysis. Of 39 newborns, 10 developed clear anemia (hemoglobin <10.0 g/dL), and 1 died, 5 developed hydrops fetalis, 4 needed intrauterine transfusion and/or exchange transfusion, and 3 received red cell transfusion after birth; overlaps were included. Among 29 neonates with no anemia, 8 needed interventions including phototherapy and γ-globulin infusion, and the remaining 21 received conservative supports only. The maternal anti-Jr^a titer, ranging between 4 and 2048, did not correlate with the severity of anemia, levels of bilirubin, or any interventions required. The DAT of red cells was positive in 29 of 36 fetuses/newborns tested, whereas it was often negative among anemic neonates (4 of 9) (P < .05). Hematopoiesis did not increase effectively, as indicated by reticulocyte ratios between 1.7% and 22.3%, even with the increase in reticulocytes in anemic neonates compared with nonanemic neonates (P < .05). Total bilirubin levels ranged broadly between 0.2 and 14.3 mg/dL but were generally low. The maternal anti-Jr^a titer and IgG3 subclass did not correlate with the morbidity of the newborns. Being identical/compatible between mothers and their infants may possibly enhance infants' morbidity, as a weak tendency was observed (P = .053). Maternal anti-Jr^a may suppress erythropoiesis in fetuses via a mechanism different from the established HDFN, such as anti-D, as evidenced by the lower reticulocyte count and small increase in bilirubin in neonates. As the anti-Jr^a titer, IgG subclass, and DAT were not correlated with the severity, the mechanism of anti-Jr^a–induced HDFN remains to be elucidated.

由于JR胎儿和新生儿（HDFN）的溶血性疾病的严重性^一个从没有症状严重贫血失配的范围，需要宫内和交换输血。我们遇到了一个新生儿，其出生于健康的母亲，在怀孕38周时具有抗Jr ^a抗体，患有中度贫血，直接抗球蛋白测试（DAT）结果阳性，红细胞生成没有增加，出生时没有黄疸。流式细胞仪显示，婴儿的红细胞Jr ^a抗原在出生时几乎呈阴性，在5周时呈双相，在生命7个月时低表达。由于Jr ^a，我们在线搜索了有关HDFN的先前案例报告不兼容。在63例报告的病例中，除25例外，本病例纳入38例进行分析。在39例新生儿中，有10例发生了明显的贫血（血红蛋白<10.0 g / dL），有1例死亡，有5例发生了胎儿水肿，有4例需要进行子宫内输血和/或交换性输血，还有3例在出生后接受了红细胞输血。包括重叠。在29名无贫血的新生儿中，有8名需要进行干预，包括光疗和γ球蛋白输注，其余21名仅获得了保守支持。母体抗JR^一个滴度，图4和2048之间的范围内，不与贫血的严重程度，胆红素水平，或者所要求的任何干预相关。在接受测试的36名胎儿/新生儿中，有29名胎儿的红细胞DAT呈阳性，而贫血新生儿中DAT的DAT通常呈阴性（9名中的4名）（P  <.05）。如网织红细胞比例介于1.7％和22.3％之间，即使贫血新生儿网织红细胞与非贫血新生儿相比增高，造血功能也不能有效增加（P  <.05）。总胆红素水平范围广泛，介于0.2和14.3 mg / dL之间，但通常较低。母体的抗Jr ^a滴度和IgG3亚类与新生儿的发病率无关。母亲和婴儿之间的相同/相容性可能会增加婴儿的发病率，因为观察到这种趋势较弱（P  = .053）。产妇抗Jr ^a可能通过不同于已建立的HDFN的机制（例如抗D）抑制胎儿的红细胞生成，这是由网织红细胞数量减少和新生儿胆红素少量增加所证明的。作为防JR^一个滴度，IgG亚类，和DAT未用的严重程度，抗Jr的机制相关^一个诱导HDFN仍有待阐明。