Steel syndrome (STLS) encompasses characteristic facies, dwarfness, irreducible bilateral hip and radial head dislocation, and carpal bone coalition due to COL27A1 mutations. Two consecutive pregnancies in a non-consanguineous couple were terminated because of severe fetal anomalies. Complete autopsies with microscopic exam were performed on both fetuses. Next-generation-based clinical exome sequencing was applied to the first fetus. Exome sequencing results, parental segregation, and affection of the second fetus were confirmed by Sanger sequencing. Both fetuses had signs consistent with STLS. Bilateral capitulum humeri absence explained radial head dislocation in STLS. Metaphyseal cartilage showed severe disorganization. Resting cartilage was hypercellular, organized in irregular nests limited by acellular matrix. Two variants in COL27A1 (c.2548G>A -p.Gly850Arg- and c.3249+1G> T) were found in both fetuses in compound heterozygosity with parental Mendelian segregation. This is the first report to include histology of STLS. The COL27A1 variants here described increase the number of mutations associated with STLS.

Steel 综合征 (STLS) 包括特征性面部、侏儒、不可复位的双侧髋关节和桡骨头脱位以及由COL27A1引起的腕骨联合突变。由于严重的胎儿异常，非近亲夫妇连续两次怀孕被终止。对两个胎儿进行了完整的尸检和显微镜检查。对第一个胎儿应用了基于下一代的临床外显子组测序。外显子组测序结果、亲本分离、二胎亲情均通过桑格测序证实。两个胎儿的体征都与 STLS 一致。双侧肱骨小头缺失解释了 STLS 中桡骨头脱位。干骺端软骨表现出严重的解体。静息软骨是细胞过多的，组织成由无细胞基质限制的不规则巢。COL27A1 中的两个变体(c.2548G>A -p.Gly850Arg- 和 c.3249+1G> T) 在具有父母孟德尔分离的复合杂合性的两个胎儿中均被发现。这是第一份包含 STLS 组织学的报告。此处描述的COL27A1变体增加了与 STLS 相关的突变数量。