Cooley H M, Keech C L, Melny B J, Menahem S, Morahan G, Kay T W
Royal Melbourne Hospital, Parkville, Victoria, Australia.
Arthritis Rheum. 1997 Feb;40(2):381-4. doi: 10.1002/art.1780400223.
Isolated congenital complete heart block (CCHB) occurs in 1/20,000 live births. More than 85% of mothers giving birth to affected infants are anti-Ro antibody positive, but only approximately 1% of babies with anti-Ro-positive mothers develop CCHB. We studied 2 sets of monozygotic twins discordant for CCHB.
Monozygosity was determined using placental examination and DNA microsatellite analysis. HLA typing was performed. Autoantibody studies were performed using counterimmunoelectrophoresis, immunoblotting, Ro 52 and Ro 60 enzyme-linked immunosorbent assay (ELISA), and indirect immunofluorescence (IIF) on Ro 60- and Ro 52-transfected HEp-2 cells.
Both sets of twins were monozygotic. They had similar birth weights. Twin 2 in the second set required a pacemaker at age 2 months. Both mothers were positive for anti-Ro 52 and anti-Ro 60 antibody, and neither had anti-La antibody on immunoblot. One set of twins was studied at birth. Similar titers of anti-Ro 52 and anti-Ro 60 antibody were found by IIF and ELISA.
There are no previous well-documented reports of monozygotic twins discordant for CCHB. These cases demonstrate that there is still discordance in the development of CCHB despite identical genetics and environmental exposure to anti-Ro antibody.
孤立性先天性完全性心脏传导阻滞（CCHB）在每20000例活产婴儿中出现1例。生育患病婴儿的母亲中超过85%抗Ro抗体呈阳性，但抗Ro抗体呈阳性的母亲所生婴儿中只有约1%会发生CCHB。我们研究了2组患CCHB的单卵双胞胎。
通过胎盘检查和DNA微卫星分析确定单合子性。进行HLA分型。使用对流免疫电泳、免疫印迹、Ro 52和Ro 60酶联免疫吸附测定（ELISA）以及对转染Ro 60和Ro 52的HEp-2细胞进行间接免疫荧光（IIF）来进行自身抗体研究。
两组双胞胎均为单卵双胞胎。他们出生体重相似。第二组中的双胞胎2在2个月大时需要起搏器。两位母亲抗Ro 52和抗Ro 60抗体均呈阳性，免疫印迹检测均未发现抗La抗体。一组双胞胎在出生时进行了研究。通过IIF和ELISA发现抗Ro 52和抗Ro 60抗体滴度相似。
此前尚无关于患CCHB的单卵双胞胎的充分记录报告。这些病例表明，尽管遗传因素相同且环境中均暴露于抗Ro抗体，但CCHB的发生仍存在不一致性。
