| IntroductionDuchenne/Becker muscular dystrophy is a common X - linked recessive genetic lethal disorders on neuro - muscular system of hu-man. They are alleic heterogenetic disorders affecting 1 in 3500 or 1 in 30000. DMD is the most severe and common type of the muscular dystrophy. Clinical characters are; onset early ( about 3 - year - old or so) , develop quickly, remove walk ability after onsetting; cow -gait, Gowers sign is positive, lower - limbs disorder earlier than upper ones, develop symmetrically, gastrocnemius, femoris quadriceps, del-toid seudohypertrophy accompanying with contracture of joint, spinal deformity, serum creatine phosphokinase ( CPK) arise obviously, muscular biopsies show malnutrition myopathy, opaque muscle fiber intervein phenomena. Vesicles in cell plasm distribute unverge; prog-nosis is severer, most of the patients died of respiratory failure, heart failure or respiratory tract infection. BMD is alleic - better type than DMD, onset later (5-20 year - old) , state of an illness relatively gentle, develop slowly, prognosis is also severe, the patients who are about 40 year - old died of respiratory failure or respiratory tract infec-tion.Dystrophin gene was positioned in Xp21.1 ~ 21.3, about 2.4 Mb long, the biggest gene as well - known at present, account for 1% ofwhole X chromosome length and 0. 1% of whole genome length, most sequences are 78 introns, coding sequence length by 79 exons is only 14 kb. Dystrophin gene is provided with high - frequent mutations and various mutation styles, thereinto deletions is the most ordinary, ac-count for 55 ~65 % or so, repetition about 5 ~ 10% , newly - muta-tion happen in 1/3 patients nowadays. Chamberlain and Beggs etal designed exon primers in the two deletions hot spot regions and estab-lished multiplex PCR systems to detect deletions, made the gene diag-nosis methods more convenient and accurate, the superiority is greater excessively than the southern blotting assay. The deletion distributions of the dystrophin gene are different characteristic according to different regions or populations. In the view of the literatures, 98% breakpoints of dystrophin gene deletion happen in the regions of the introns. The distribution of the breakpoints is unrandom, sequence differences in introns exist significantly in different nations. We detected 120 DMD/ BMD patients in the northeastern of China via multiplex PCR and ana-lyze the distribution of the breakpoints of dystrophin gene deletions, the stability of introns 44 ~ 51 after excluding the effect of intron "s lenghth and the best primers combination, moreover applied genetic counselling and prenatal gene diagnosis for 29 high - risk DMD/BMD pregnancies.Material120 DMD/BMD patients in the northeastern of China were diag-nosed. Among them, there are 18 BMD isolated patients and 22 famil-iar histories of the 102 DMD patients. A sample of 1 ~5ml blood was collected by venipuncture from each individual. 29 mothers of DMD/ BMD probands (7 familiar histories )who required prenatal gene diag-nosis were drawn fetus villus during pregnant earlier period (45 ~ 60 days) or amniotic fluid during metaphase period (16 ~20 weeks).MethodDNA was extracted from peripheral blood. To screen deletion dis-tribution of patients via mulplex PCR; to detect the distribution of the breakpoints of the deleted - probands by PCR. After drawing fetus DNA from fetus villus or amniotic fluid , PCR amplification to judge fetus sex. Male fetus were detected deletion by mulplex PCR method . Female fetus or male fetus who haven t been detected deletion were ap-plied for STR haplotype linkage analysis, (detail to another paper)Results59 deletions of 120 DMD/BMD patients were screened, the dele-tion frequency is 49.2%. 40 cases (67. 8% ) located in the regions of exons 45 ~53, 13 cases (22% ) located in the region of exons 8 ~ 19 and in 5 cases (8. 5% ) deletions were scattered over both regions, still one case( 1. 7% ) was checked up whose deletions lay in exon 34 and 43. About 66. 4...
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