[Mechanism of translocation between chromosomes 4q and 10q in facioscapulohumeral muscular dystrophy].
摘要
OBJECTIVE: To investigate the translocation between chromosomes 4q and 10q and its putative correlation with facioscapulohumeral muscular dystrophy (FSHD). METHODS: Double digestion of the genomic DNA of 50 controls and 45 FSHD cases, 16 cases of sporadic FSHD and 19 cases of familial FSHD from 7 families, with restriction enzymes BglII and BlnI was followed by separation and Southern blotting with the probe p13E-11. By Scion Image program, the density of hybridized fragments was analyzed and the 4q:10q density ratio was then calculated to infer the types of 4q-10q translocation. The frequencies of translocation among the controls, sporadic FSHD cases, and familial cases were compared. RESULTS: In the 95 subjects 4 different translocation types were detected with a translocation rate of 17.89%. Both the rate of 4q-->10q translocation and the rate of 10q-->4q translocation were 8.0% among the healthy controls. Only 4q-->10q translocation was found in sporadic FSHD cases with a frequency of 43.75%, while only 10q-->4q translocation was found in familial FSHD patients with a frequency of 6.89%. The frequency of 4q-->10q translocation in the sporadic FSHD cases was significantly higher than that in the control group (chi(2) = 11.154, P < 0.001), while the frequency of 10q-->4q translocation in the familial FSHD cases was not significantly different from that in the controls (chi(2) = 0.012, P > 0.5). CONCLUSION: Frequent translocations between chromosomes 4q and 10q occur in normal population and FSHD cases, while the 4q-->10q translocation is only related to sporadic FSHD. Excessive loss or conversion (to 10q26) of 4q35 D4Z4 repeats, caused by 4q-10q interactions, may be essential for the mechanism of this disorder.