Importance Osteosarcoma, the most common malignant bone tumor in children and adolescents, occurs in a high number of cancer predisposition syndromes that are defined by highly penetrant germline mutations. The germline genetic susceptibility to osteosarcoma outside of familial cancer syndromes remains unclear.

Objective To investigate the germline genetic architecture of 1244 patients with osteosarcoma.

Design, Setting, and Participants Whole-exome sequencing (n = 1104) or targeted sequencing (n = 140) of the DNA of 1244 patients with osteosarcoma from 10 participating international centers or studies was conducted from April 21, 2014, to September 1, 2017. The results were compared with the DNA of 1062 individuals without cancer assembled internally from 4 participating studies who underwent comparable whole-exome sequencing and 27 173 individuals of non-Finnish European ancestry who were identified through the Exome Aggregation Consortium (ExAC) database. In the analysis, 238 high-interest cancer-susceptibility genes were assessed followed by testing of the mutational burden across 736 additional candidate genes. Principal component analyses were used to identify 732 European patients with osteosarcoma and 994 European individuals without cancer, with outliers removed for patient-control group comparisons. Patients were subsequently compared with individuals in the ExAC group. All data were analyzed from June 1, 2017, to July 1, 2019.

Main Outcomes and Measures The frequency of rare pathogenic or likely pathogenic genetic variants.

Results Among 1244 patients with osteosarcoma (mean [SD] age at diagnosis, 16 [8.9] years [range, 2-80 years]; 684 patients [55.0%] were male), an analysis restricted to individuals with European ancestry indicated a significantly higher pathogenic or likely pathogenic variant burden in 238 high-interest cancer-susceptibility genes among patients with osteosarcoma compared with the control group (732 vs 994, respectively; P = 1.3 × 10⁻¹⁸). A pathogenic or likely pathogenic cancer-susceptibility gene variant was identified in 281 of 1004 patients with osteosarcoma (28.0%), of which nearly three-quarters had a variant that mapped to an autosomal-dominant gene or a known osteosarcoma-associated cancer predisposition syndrome gene. The frequency of a pathogenic or likely pathogenic cancer-susceptibility gene variant was 128 of 1062 individuals (12.1%) in the control group and 2527 of 27 173 individuals (9.3%) in the ExAC group. A higher than expected frequency of pathogenic or likely pathogenic variants was observed in genes not previously linked to osteosarcoma (eg, CDKN2A, MEN1, VHL, POT1, APC, MSH2, and ATRX) and in the Li-Fraumeni syndrome-associated gene, TP53.

Conclusions and Relevance In this study, approximately one-fourth of patients with osteosarcoma unselected for family history had a highly penetrant germline mutation requiring additional follow-up analysis and possible genetic counseling with cascade testing.

重要的 骨肉瘤是儿童和青少年中最常见的恶性骨肿瘤，它发生在由高度渗透性生殖系突变所定义的许多癌症易感综合症中。家族癌症综合症以外的骨肉瘤的生殖遗传易感性尚不清楚。

目的 探讨1244例骨肉瘤患者的生殖系遗传结构。

设计，设置和参与者 2014年4月21日至2017年9月1日，对来自10个参与国际中心或研究的1244例骨肉瘤患者的DNA进行了全外显子组测序（n = 1104）或靶向测序（n = 140）。通过4个参与研究进行了内部可组装的1062名无癌个体的DNA的内部组装，这些研究均经过了可比的全外显子测序，并通过外显子聚集体联盟（ExAC）数据库鉴定了27 173例非芬兰欧洲血统的个体。在分析中，评估了238个高关注度的癌症易感基因，然后测试了736个其他候选基因的突变负担。使用主成分分析来确定732例欧洲骨肉瘤患者和994例没有癌症的欧洲个体，移除异常值以进行患者与对照组的比较。随后将患者与ExAC组中的患者进行比较。从2017年6月1日到2019年7月1日分析所有数据。

主要结果和措施 罕见病原体或可能的病原体遗传变异的频率。

结果 在1244例骨肉瘤患者中（诊断时的平均[SD]年龄为16 [8.9]岁[范围，2-80岁]； 684例[55.0％]为男性），仅限于具有欧洲血统的个体进行的分析表明与对照组相比，骨肉瘤患者中238个高关注度癌症易感基因的致病性或潜在致病性变异负担更高（分别为732和994；P  = 1.3×10 ^-18）。在1004例骨肉瘤患者中发现了一种致病性或可能致病性的癌症易感基因变异体（28.0％），其中近四分之三具有映射到常染色体显性基因或已知的骨肉瘤相关癌症易感综合征的变异体基因。致病或可能致病的癌症易感性基因变异的频率在对照组中为1062个个体中的128个（12.1％），在ExAC组中为27173个个体中的2527个（9.3％）。在先前未与骨肉瘤相关的基因（例如CDKN2A，MEN1，VHL，POT1，APC，MSH2和ATRX）以及与Li-Fraumeni综合征相关的基因中，发现了高于预期频率的致病性或可能致病性变体，TP53。

结论与相关性 在这项研究中，约有四分之一未选择家族史的骨肉瘤患者具有高度渗透性的种系突变，需要进一步的随访分析和可能的级联测试遗传咨询。