| Objective 1. To investigate the EcoRI Length Polymorphism and the deletion of D4Z4 repeats within 4q35 in Chinese population. 2. To identify the instability of 4q35 region.and the translocation between subtelomere of chromosomes 4q and 1 Oq, and their putative roles in the deletion mechanism of D4Z4 repeats. 3. To estabilsh the phenotype-genotype correlation in Chinese FSHD patients and obtain preliminary insight into the pathogenesis of FSHD. 4. To develop a gene diagnosis protocol pertinent to the Characteristics of Chinese population.Methods 1. The 4q35 EcoRI/pl3E-ll fragments of normal Chinese population and FSHD patients were detected based on double-digestion of genomic DNA with EcoR/Hindlll and subsequent Southern blotting with the probe p!3E-ll. The fragments were analyzed by the software ImageMaster TotalLab vl.ll and the sizes of each fragment were then calculated. 2. The detection and differentiation of the homologous fragment located on 10q26 were performed using EcoRI/Blnl double digestion associated Southern blotting method. 3. The 4q35- and 10q26-type D4Z4 units were detected with Bglll/Blnl double digestion and Southern bloting. The density of the hybridized fragments was analyzed by the image quantifying program and the 4q:10q ratio was then calculated. Based on the ratios, the types of 4q-10q translocation were inferred. Then the comparison of the frequency of translocation, using chi-square test, was performed among normal population, sporadic FSHD cases and familial cases. 4. Linear regression analysis was performed to establish the correlation between age of onset and disability on one hand, and the size of EcoRI fragment, on the other. Comparison of onset age and EcoRI size was performed, using t test, between sexes and translocated and non-translocated cases. 5. Gene diagnosiswas performed for FSHD cases and clinically suspected cases with the combined application of double digestion method and dosage testResults: 1. Sizes of EcoRI/pl3E-l 1 fragments and their chromosomal derivation: In each of the 33 controls, only a 4q35-derived allele ranging from 37.2 to 40kb was detected. In each of the 25 familial and 17 sporadic cases, there are two 4q35-derived fragments were detected, the smaller one of which varies from 18~30.1kb. And in each of the other 3 controls and 4 sporadic cases, a 21.5~28kb 10q26 homologous fragment was found. 2. Dosage test and analysis: In all subjects, 5 different 4q:10q ratios corresponding to 4 translocation types were detected. Only 4q-10q translocation was found in sporadic cases whereas only 10-4q translocation was found in familial individuals. The frenquency of translocation in control, sporadic patients and familial cases is 16.7%, 64.7% and 8%, respectively. The frequency of sporadic individuals is significantly higher than that of the familial individuals (;r =15.22, PO.001) and controls ( x2 =9.86, PO.01), while thedifference between familial and control individuals was of no significance ( j2 =0.361,P>0.05). 3. Phenotype-genotype correlation: In sporadic cases'and propositus of FSHD families, the age of onset and disability was significantly relevant to the size of EcoRI fragment ( r=0.960, PO.01; r=0.969, P<0.05). In contrast to the non-translocated patients, the patients carry 4q-10q translocation had a smaller fragment and an earlier onset. (P<0.05) . There was no significant inter-sexual difference in the size of EcoRI fragment and age of onset (P>0.05). Although all patients in the same family share the same causal fragment, there was profound intra-familial variation of onset age and severity.. 4. Gene diagnosis: A 4q35 EcoRI fragment smaller than 31 kb was unexceptionally detected in all the cases to be diagnosed, while no such fragment was detected in the suspected patient.. Dosage analysis for these cases suggested that no 4q-10q translocation were detected in familial cases whereas 2 sporadic were found to carry a translocation.Conclusions: 1. There is an EcoRI fragment length polymorphism within 4q35 in Chinese population...
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