1998 Fiscal Year Final Research Report Summary
Molecular mechanism for inherited thyroxine-binding globulin excess and isolated growth hormone deficiency
| Project/Area Number |
09671082
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
内分泌・代謝学
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| Research Institution | Aichi Medical University |
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Principal Investigator |
MORI Yuichi Aichi Medical University, Associate Professor, 医学部, 助教授 (70230084)
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| Project Period (FY) |
1997 – 1998
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| Keywords | TBG / isolated GH deficiency / TBG excess / gene amplification / PCR / FISH / cosmid vector / Chromosome walking |
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| Research Abstract |
1. In this study, new 3 TBG excess families were analyzed, one familial and 2 sporadic cases. Amplification of the TBG gene was detected in 1 familial and 1 sporadic case by using duplex PCR-HPLC method but not in 1 sporadic case, in which a search for the molecular defect is in progress.
2. The gene dosage of TBG was estimated in 8 families with inherited TBG excess (4 Japanese and 4 Caucasian families) and 3 sporadic Japanese family by using duplex PCR- HPLC method. Amplification of the TBG gene was detected in 10/11 families, 3 fold in 5 families and 2 fold in 3 inherited families and 2 sporadic cases. Serum TBG values were corresponded to TBG gene dosage. Then gene amplification was shown to be a main mechanism for inherited TBG excess. As 2 fold amplification was shown in both of 2 sporadic cases, the gene amplification was considered to increase from 2 to 3 fold by a unequal crossing over of the chromosome.
3. Amplification of the TBG gene was also evaluated in 6 Japanese and one Caucasian families with FISH using chromosomes and a TBG probe. Although, 3 fold amplification, corresponding to the results of PCR-HPLC analysis, was demonstrated in 1 Japanese and 1 Caucasian family, other 5 families were shown to be indistinguishable from normal subjects. The size of the amplified unit might be smaller than the detection limit of FISH.
4. In order to clarify the mechanism for the gene amplification, RFLPs were evaluated in 5 Japanese families using genomic DNAs and 12 restriction enzymes. Nevertheless, no RFLP was detected in all subjects, demonstrating that a breakpoint of amplified unit exist outside of 52 kbp covered by 12 enzymes. Cosmid libraries were constructed from genomic DNAs of a normal and a male TBG excess subject complicated with isolated GH deficiency. Then, DNA fragments of 75 kbp in the normal and 82 kbp in the affected subject were obtained by chromosome walking. No differences were so far detected between 2 subjects.
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