Levanat Sonja, Situm Mirna, Crnić Ivana, Marasović Dujomir, Puizina-Ivić Neira, Pokupcić Nikola, Musani Vesna, Komar Arijana, Kubat Milovan, Furac Ivana, Karija-Vlahović Monika, Krizanac Simun
Division of Molecular Medicine, Ruder Bosković Institute, Bijenicka 54, 10000 Zagreb, Croatia.
Croat Med J. 2003 Aug;44(4):418-24.
To examine constitutional alterations of CDKN2A/p16INK4A locus as a potential indicator of melanoma predisposition among the first-degree relatives of patients with malignant melanoma.
The study included eight families with a single member affected with melanoma. Members of the families were screened for allelic cosegregation with 9p21 region polymorphic markers IFNA, D9S126, and D9S104. The patient's tumors were screened for loss of heterozygosity (LOH) with the same markers, as well as for single strand conformational polymorphism (SSCP) variability of CDKN2A. In suspect cases, constitutional DNA was examined by SSCP and direct sequencing.
LOH was detected in four cases, and SSCP indicated variability in at least one CDKN2A exon in these tumor samples. In three of four LOH cases, the remaining allele cosegregated within the family, which was interpreted as a preliminary indicator of potential genetic predisposition. In one of these three families, we found constitutional CDKN2A mutations in the patient and one of the relatives. In the second family, only the patient had the constitutionally altered gene, whereas no constitutional CDKN2A alterations were detected in the third family. All significant mutations were different and had not been reported before.
We detected one case of melanoma predisposition among unaffected family members, which corresponded to statistical expectations for such a small number of screened families. Since constitutional mutations of CDKN2A exons have limited incidence, our stepwise approach seemed to be more informative and more affordable than straightforward CDKN2A sequencing of all subjects.
研究CDKN2A/p16INK4A基因座的结构改变，作为恶性黑色素瘤患者一级亲属中黑色素瘤易感性的潜在指标。
该研究纳入了8个有单个成员患黑色素瘤的家庭。对家庭成员进行9p21区域多态性标记IFNA、D9S126和D9S104的等位基因共分离筛查。用相同标记对患者肿瘤进行杂合性缺失（LOH）筛查，以及CDKN2A的单链构象多态性（SSCP）变异筛查。在可疑病例中，通过SSCP和直接测序检查结构DNA。
在4例中检测到LOH，并且SSCP表明这些肿瘤样本中至少一个CDKN2A外显子存在变异。在4例LOH病例中的3例中，剩余等位基因在家族内共分离，这被解释为潜在遗传易感性的初步指标。在这3个家族中的1个家族中，我们在患者和1名亲属中发现了CDKN2A基因的结构突变。在第二个家族中，只有患者有结构改变的基因，而在第三个家族中未检测到CDKN2A基因的结构改变。所有显著突变均不同且此前未被报道。
我们在未受影响的家庭成员中检测到1例黑色素瘤易感性病例，这与对如此少量筛查家族的统计预期相符。由于CDKN2A外显子的结构突变发生率有限，我们的逐步方法似乎比直接对所有受试者进行CDKN2A测序更具信息性且更经济实惠。
