DUCHENNE MUSCULAR DYSTROPHY (DMD) Clinical features: Progressive muscle stru weakness,pseudohy muscles; onset in early childhood, death by of mu cidence I in 3000 to I in 3500 Pathophysiology male births, carrier frequency -l in 2500 females X-linked recessive, lethal te in males fibe 1/3 of patients are new mutants; 2/3 have carrier mothers is: Possib Gene location Xp2 Extremely large gene (more than 2000 kb) High mutation rate (1×10-4) probably So due to large size of gene Significance: A clas. rec mutations are dele- tions, and about 6% are duplications first Germline mosaicism in rare cases Allelic mutations in the same gene cause a milder disorder rans Becker muscular dys Basic defect abnormality of the 诊断方法 抽 提先证者外周血gDNA 用 16对引物扩增DMD基因的外显诊断方法： 抽 提先证者外周血gDNA ↓ 用 16对引物扩增DMD基因的外显 子 │ ↓————— ————————————— ————————↓