新疆80例恶性黑素瘤BRAF基因突变分析

Analysis of BRAF gene mutations in 80 patients with malignant melanoma in Xinjiang Uygur Autonomous Region

目的探讨BRAF基因突变与恶性黑素瘤临床表现的关系。方法PCR及DNA直接测序法对新疆80例恶性黑素瘤及30例正常皮肤石蜡包埋组织BRAF基因11、15外显子进行检测。结果80例恶性黑素瘤19例发生BRAF基因突变，突变率为23．8％（19／80）；有17例突变发生于15外显子，突变率为89．5％（17／19），其中V600E突变占BRAF基因15外显子突变的88．2％（15／17）；2例突变位于11外显子，突变率10．5％（2／19）；30例正常皮肤组织均未发现BRAF基因突变。患者平均发病年龄为57．5岁，年龄在60岁以下患者BRAF基因突变率显著高于60岁以上（r=6．613，P〈0．05）。黏膜、肢端、非肢端突变率分别为：18．2％（4／21），14．7％（5，34），41．7％（10／24），差异具有统计学意义（r=6．167，P〈0．05）。BRAF基因突变与恶性黑素瘤患者性别、民族、有无淋巴结转移无明显相关性（P〉0．05）。结论BRAF基因仍为新疆地区恶性黑素瘤热点突变基因，且以该基因15外显子V600E突变为主。BRAF基因突变与恶性黑素瘤患者发病年龄、发病部位密切相关，而与民族、性别、有无淋巴结转移无相关性。

Objective To assess the relationship between BRAF gene mutations and clinical phenotype of malignant melanoma. Methods Tissue specimens were collected from the lesions of 80 patients with malignant melanoma, and from the normal skin of 30 patients with trauma in the Department of Plastic Surgery or General Surgery, and subjected to paraffin embedding and DNA extraction. PCR was performed to amplify the exon 11 and 15 of BRAF gene followed by DNA sequencing. Chi-square test and Fisher＇s exact test were carried out to assess the relationship between BRAF gene mutations and clinical phenotypes of malignant melanoma. Results BRAF gene mutations were found in 19 （23.8%） of the 80 malignant melanoma specimens. Among the 19 mutation- positive specimens, 17 （88.2%） carried mutations in exon 15 of BRAF gene with V600E as the most frequent （88.2%, 15/17） mutation type, and 2 （10.5%） carried mutations in exon 11. No mutation was found in any of the normal skin tissue specimens. The average age at onset was 57.5 years in these patients. The frequency of BRAF gene mutation was significantly higher in patients younger than 60 years than in those older than 60 years （37.1% vs. 13.3%, X2= 6.613, P 〈 0.05）. A significant difference was observed in the frequency of BRAF gene mutation among tissue specimens of mucosal, acral and non-acral malignant melanoma （18.2% （4/2t） vs. 14.7% （5/34） vs. 41.7% （10/24）, X2= 6.167, P 〈 0.05）. There was no significant association between BRAF gene mutation and gender, race or lymph node metastasis （all P 〉 0.05）. Conclusions BRAF gene is a hot spot for mutations in patients with malignant melanoma in Xinjiang Uygur Autonomous Region, with V6OOE point mutation in exon 15 as the most frequent mutation type. BRAF gene mutations appear to be closely correlated with the age at onset of and lesional sites in, but uncorrelated with gender and race of or lymph node metastasis in, patients with malignant melanoma.