Functional characterization of 84 PALB2 variants of uncertain significance.,Genetics in Medicine

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Functional characterization of 84 PALB2 variants of uncertain significance.
Genetics in Medicine ( IF 8.8 ) Pub Date : 2019-10-21 , DOI: 10.1038/s41436-019-0682-z
Timothy Wiltshire ₁ , Mandy Ducy _{2,

3,

4} , Tzeh Keong Foo ₅ , Chunling Hu ₁ , Kun Y Lee ₁ , Anil Belur Nagaraj ₁ , Amélie Rodrigue _{2,

4} , Thiago T Gomes ₆ , Jacques Simard ₃ , Alvaro N A Monteiro ₇ , Bing Xia ₅ , Marcelo A Carvalho ₆ , Jean-Yves Masson _{2,

4} , Fergus J Couch ₁

Affiliation

Purpose

Inherited pathogenic variants in PALB2 are associated with increased risk of breast and pancreatic cancer. However, the functional and clinical relevance of many missense variants of uncertain significance (VUS) identified through clinical genetic testing is unclear. The ability of patient-derived germline missense VUS to disrupt PALB2 function was assessed to identify variants with potential clinical relevance.

Methods

The influence of 84 VUS on PALB2 function was evaluated using a cellular homology directed DNA repair (HDR) assay and VUS impacting activity were further characterized using secondary functional assays.

Results

Four (~5%) variants (p.L24S,c.71T>C; p.L35P,c.104T>C; pI944N,c.2831T>A; and p.L1070P,c.3209T>C) disrupted PALB2-mediated HDR activity. These variants conferred sensitivity to cisplatin and a poly(ADP-ribose) polymerase (PARP) inhibitor and reduced RAD51 foci formation in response to DNA damage. The p.L24S and p.L35P variants disrupted BRCA1–PALB2 protein complexes, p.I944N was associated with protein instability, and both p.I944N and p.L1070P mislocalized PALB2 to the cytoplasm.

Conclusion

These findings show that the HDR assay is an effective method for screening the influence of inherited variants on PALB2 function, that four missense variants impact PALB2 function and may influence cancer risk and response to therapy, and suggest that few inherited PALB2 missense variants disrupt PALB2 function in DNA repair.

中文翻译：

84 个意义不确定的 PALB2 变体的功能表征。

目的

PALB2中的遗传性致病变异与乳腺癌和胰腺癌的风险增加有关。然而，通过临床基因检测鉴定的许多意义不确定的错义变异（VUS）的功能和临床相关性尚不清楚。评估了患者衍生的种系错义 VUS 破坏 PALB2 功能的能力，以识别具有潜在临床相关性的变体。

方法

使用细胞同源定向 DNA 修复 (HDR) 测定评估 84 VUS 对 PALB2 功能的影响，并使用二级功能测定进一步表征 VUS 影响活性。

结果

四种 (~5%) 变体 (p.L24S,c.71T>C; p.L35P,c.104T>C; pI944N,c.2831T>A; 和 p.L1070P,c.3209T>C) 破坏了 PALB2-介导的 HDR 活动。这些变体赋予了对顺铂和聚（ADP-核糖）聚合酶（PARP）抑制剂的敏感性，并减少了响应DNA损伤的RAD51病灶形成。p.L24S 和 p.L35P 变体破坏了 BRCA1-PALB2 蛋白复合物，p.I944N 与蛋白质不稳定性有关，并且 p.I944N 和 p.L1070P 都将 PALB2 错误定位到细胞质中。