检查 并非所有突变均是已知的。2/3 以上的病例存在 4 种最常见突变(M680I、M694V、V726A 和 M694I)。[19]Brik R, Litmanovich D, Berkowitz D, et al. Incidence of familial Mediterranean fever (FMF) mutations among children of Mediterranean extraction with functional abdominal pain. J Pediatr. 2001;138:759-762.http://www.ncbi.nlm.nih.gov/pubmed/11343058?tool=bestpractice.com
E148Q 氨基酸替代的作用存在争议,这种替代是谷氨酰胺 (Q) 替代谷氨酸 (E)。最初,这个序列变体被描述为导致疾病的突变,外显率低,症状轻。[11]Gershoni-Baruch R, Brik R, Shinawi M, et al. The differential contribution of MEFV mutant alleles to the clinical profile of familial Mediterranean fever. Eur J Hum Genet. 2002;10:145-149.http://www.nature.com/ejhg/journal/v10/n2/full/5200776a.htmlhttp://www.ncbi.nlm.nih.gov/pubmed/11938447?tool=bestpractice.com[20]Aganna E, Hawkins PN, Ozen S, et al. Allelic variants in genes associated with hereditary periodic fever syndromes as susceptibility factors for reactive systemic AA amyloidosis. Genes Immun. 2004;5:289-293.http://www.nature.com/gene/journal/v5/n4/full/6364070a.htmlhttp://www.ncbi.nlm.nih.gov/pubmed/15071491?tool=bestpractice.com[21]Akar N, Akar E, Yalçinkaya F. E148Q of the MEFV gene causes amyloidosis in familial Mediterranean fever patients. Pediatrics. 2001;108:215.http://www.ncbi.nlm.nih.gov/pubmed/11452963?tool=bestpractice.com然而,一些研究者在近期研究中发现,患者和对照人群的 E148Q 频率相似,因此表明这只不过是良性多态性。目前已知 E148Q 变体比较常见,其致病意义尚不明确,并且作为唯一的 MEFV 变体,不能支持 FMF 诊断。[60]Giancane G, Ter Haar NM, Wulffraat N, et al. Evidence-based recommendations for genetic diagnosis of familial Mediterranean fever. Ann Rheum Dis. 2015;74:635-641.http://www.ncbi.nlm.nih.gov/pubmed/25628446?tool=bestpractice.com
临床诊断 FMF 时,不同等位基因上存在 2 个突变(纯合性或复合杂合性)即可确诊。[49]Grateau G, Pêcheux C, Cazeneuve C, et al. Clinical versus genetic diagnosis of familial Mediterranean fever. QJM. 2000;93:223-229.http://qjmed.oxfordjournals.org/content/93/4/223.longhttp://www.ncbi.nlm.nih.gov/pubmed/10787450?tool=bestpractice.com仅存在 1 个突变时,无法确诊;然而,若出现典型临床症状,则不应排除诊断,因确实存在一些罕见或未知的突变。The registry of hereditary auto-inflammatory disorders mutations[32]Kone-Paut I, Hentgen V, Guillaume-Czitrom S, et al. The clinical spectrum of 94 patients carrying a single mutated MEFV allele. Rheumatology (Oxford). 2009;48:840-842.http://rheumatology.oxfordjournals.org/content/48/7/840.longhttp://www.ncbi.nlm.nih.gov/pubmed/19465590?tool=bestpractice.com[33]Marek-Yagel D, Berkun Y, Padeh S, et al. Clinical disease among patients heterozygous for familial Mediterranean fever. Arthritis Rheum. 2009;60:1862-1866.http://onlinelibrary.wiley.com/doi/10.1002/art.24570/fullhttp://www.ncbi.nlm.nih.gov/pubmed/19479871?tool=bestpractice.com[34]Moradian MM, Sarkisian T, Ajrapetyan H, et al. Genotype-phenotype studies in a large cohort of Armenian patients with familial Mediterranean fever suggest clinical disease with heterozygous MEFV mutations. J Hum Genet. 2010;55:389-393.http://www.ncbi.nlm.nih.gov/pubmed/20485448?tool=bestpractice.com那些相同的真杂合子可能会显示 FMF 的完整临床表现。像许多隐性疾病一样,一些杂合子患者也可能具有较少的临床体征。尽管基因诊断未为每位患者提供最终解决方案,但已成为确诊 FMF 的一大重要诊断工具,从而提供适当的治疗,尤其是在儿童中。[54]Simon A, van der Meer JW, Vesely R, et al. Approach to genetic analysis in the diagnosis of hereditary autoinflammatory syndromes. Rheumatology (Oxford). 2006;45:269-273.http://rheumatology.oxfordjournals.org/cgi/content/full/45/3/269http://www.ncbi.nlm.nih.gov/pubmed/16234278?tool=bestpractice.com
市售检测试剂盒包括“FMF StripAssay”(可提供更快、更精确的结果)。
为进行基因检测,医生应联系当地实验室供应商(或大学中心的当地研究实验室)。