van Puijenbroek Marjo, Nielsen Maartje, Tops Carli M J, Halfwerk Hans, Vasen Hans F A, Weiss Marjan M, van Wezel Tom, Hes Frederik J, Morreau Hans
Department of Pathology, Leiden University Medical Center, Leiden, the Netherlands.
Clin Cancer Res. 2008 Jan 1;14(1):139-42. doi: 10.1158/1078-0432.CCR-07-1705.
To assess the feasibility of identifying patients with (atypical) MUTYH-associated polyposis (MAP) by KRAS2 c.34G > T prescreening followed by MUTYH hotspot mutation analysis in formalin-fixed paraffin-embedded tissue (FFPE).
We collected 210 colorectal FFPE tumors from 192 individuals who presented with <10 adenomas or familial mismatch repair proficient colorectal carcinomas with <10 concomitant adenomas. The tissues were tested for somatic KRAS2 mutations and for three Dutch hotspot MUTYH germ line mutations (p.Tyr165Cys, p.Gly382Asp, and p.Pro391Leu) by sequencing analysis.
The c.34G > T, KRAS2 transversion was detected in 10 of 210 tumors. In one of these 10 cases, a monoallelic p.Gly382Asp MUTYH mutation was found and a full MUTYH analysis in leukocyte DNA revealed an unclassified variant p.Met269Val. This was in a 61-year-old patient with a cecum carcinoma and three adenomas. After further requests, her family case history revealed that her brother had had between 10 and 15 adenomas and turned out to carry both MUTYH germ line mutations. MUTYH hotspot mutation screening in 182 patients without the somatic c.34G > T KRAS2 mutation led to the detection of three monoallelic germ line MUTYH mutation carriers.
KRAS2 c.34G > T somatic prescreening, followed by MUTYH hotspot mutation analysis when positive, can identify patients with (atypical) MAP. If heterozygous hotspot MUTYH mutations are identified, a complete germ line MUTYH mutation screening should be carried out if possible. Immediate MUTYH hotspot mutation analysis is a practical alternative in patients with >10 adenomas or in cases of multiple colorectal carcinomas in one generation for which only FFPE tissue is available.
通过在福尔马林固定石蜡包埋组织（FFPE）中进行KRAS2基因c.34G>T预筛查，随后进行MUTYH热点突变分析，评估识别（非典型）MUTYH相关息肉病（MAP）患者的可行性。
我们从192名个体中收集了210例结直肠FFPE肿瘤，这些个体患有少于10个腺瘤或家族性错配修复功能正常且伴有少于10个腺瘤的结直肠癌。通过测序分析检测组织中的KRAS2体细胞突变以及三种荷兰热点MUTYH种系突变（p.Tyr165Cys、p.Gly382Asp和p.Pro391Leu）。
在210例肿瘤中的10例中检测到KRAS2基因c.34G>T颠换。在这10例中的1例中，发现了单等位基因p.Gly382Asp MUTYH突变，并且对白细胞DNA进行的完整MUTYH分析显示了一个未分类的变异p.Met269Val。这是一名患有盲肠癌和3个腺瘤的61岁患者。在进一步询问后，她的家族病史显示她的哥哥曾有10至15个腺瘤，结果发现携带两个MUTYH种系突变。对182例无KRAS2基因c.34G>T体细胞突变的患者进行MUTYH热点突变筛查，发现了3名单等位基因种系MUTYH突变携带者。
KRAS2基因c.34G>T体细胞预筛查，阳性时随后进行MUTYH热点突变分析，可识别（非典型）MAP患者。如果识别出杂合热点MUTYH突变，应尽可能进行完整的种系MUTYH突变筛查。对于患有超过10个腺瘤的患者或一代中有多个结直肠癌且仅有FFPE组织可用的病例，立即进行MUTYH热点突变分析是一种实用的替代方法。
