MacCollin M, Mohney T, Trofatter J, Wertelecki W, Ramesh V, Gusella J
Molecular Neurogenetics Unit, Massachusetts General Hospital, Charlestown 02129.
JAMA. 1993 Nov 17;270(19):2316-20. doi: 10.1001/jama.270.19.2316.
To define the DNA mutation causing neurofibromatosis 2 (NF2), a severe genetic disorder involving the development of multiple nervous system tumors in adulthood, in a large, well-studied NF2 pedigree previously used to chromosomally map and to isolate the disease gene.
Single-strand conformational polymorphism (SSCP) and DNA sequence analysis of the NF2 gene amplified from affected and unaffected family members.
Affected, unaffected, and at-risk members of a large pedigree segregating NF2, an autosomal dominant disorder caused by inactivation of the merlin tumor suppressor encoded in chromosome band 22q12.
A DNA alteration in the merlin coding sequence caused a shift on SSCP gels that was characteristic of the disease chromosome in this NF2 pedigree, being transmitted with the disorder, present only in affected members of the pedigree, absent in unaffected members of the family, and absent from 158 unrelated individuals. The alteration caused substitution of a tyrosine for an asparagine at position 220 of the merlin protein, in a region highly conserved in closely related members of the family of cytoskeletal-associated proteins. The DNA change could also be detected by restriction enzyme digestion with Rsa I.
Current practice dictates screening of all those "at risk" for NF2 with magnetic resonance imaging, but the frequency and duration of screening are problematic because of the variable course of the disease. The identification of a DNA alteration in the NF2 gene will permit predictive molecular testing of individuals at risk in this specific family, sparing the expense and emotional burden of protracted screening programs. This information, by providing diagnostic certainty, should also reduce psychological and financial burdens and improve medical care for affected family members. A similar approach to defining the underlying lesion and developing a predictive test is applicable in any documented NF2 family.
在一个此前用于染色体定位和分离疾病基因的、经过充分研究的大型神经纤维瘤病2型（NF2）家系中，确定导致NF2的DNA突变。NF2是一种严重的遗传性疾病，成年期会出现多个神经系统肿瘤。
对从患病和未患病家庭成员中扩增出的NF2基因进行单链构象多态性（SSCP）和DNA序列分析。
一个大型家系中患NF2、未患病以及有患病风险的成员。NF2是一种常染色体显性疾病，由位于22号染色体q12带的默林肿瘤抑制基因失活引起。
默林编码序列中的一个DNA改变导致了SSCP凝胶上的条带迁移，这是该NF2家系中疾病染色体的特征，与疾病一同遗传，仅存在于家系中的患病成员，在家系的未患病成员中不存在，在158名无关个体中也不存在。该改变导致默林蛋白第220位的天冬酰胺被酪氨酸取代，该区域在细胞骨架相关蛋白家族的密切相关成员中高度保守。用Rsa I进行限制性酶切也能检测到该DNA变化。
目前的做法是用磁共振成像对所有有NF2“风险”的人进行筛查，但由于疾病进程的变化，筛查的频率和持续时间存在问题。NF2基因中DNA改变的鉴定将允许对这个特定家系中有风险的个体进行预测性分子检测，省去长期筛查项目的费用和情感负担。通过提供诊断确定性，这一信息还应减轻心理和经济负担，并改善对患病家庭成员的医疗护理。定义潜在病变并开发预测性检测的类似方法适用于任何已记录的NF2家系。
